1 00:00:16,610 --> 00:00:19,390 PHILIP GREENSPUN: We're going to talk about meteorology. 2 00:00:19,390 --> 00:00:25,240 So as pilots, we're just trying to understand the basics. 3 00:00:25,240 --> 00:00:27,280 And in terms of passing the exam, 4 00:00:27,280 --> 00:00:31,340 you don't need to be a physicist. 5 00:00:31,340 --> 00:00:34,210 You just mostly are trying to learn 6 00:00:34,210 --> 00:00:40,060 stuff that will help you fly within the VFR weather minimums 7 00:00:40,060 --> 00:00:44,230 and predict when those minimums aren't likely to be met 8 00:00:44,230 --> 00:00:46,990 or when there's going to be really serious hazards, 9 00:00:46,990 --> 00:00:48,550 such as thunderstorms. 10 00:00:48,550 --> 00:00:51,160 All right, this will be on the test. 11 00:00:51,160 --> 00:00:54,620 You have to memorize all of this. 12 00:00:54,620 --> 00:00:55,710 Well, you kind of do. 13 00:00:55,710 --> 00:00:57,530 Anyways, they want you-- 14 00:00:57,530 --> 00:01:04,310 you will have to learn some of this stuff for the exam. 15 00:01:04,310 --> 00:01:07,730 In reality around here, almost all airspace 16 00:01:07,730 --> 00:01:09,380 is at least class echo. 17 00:01:09,380 --> 00:01:10,680 That's controlled airspace. 18 00:01:10,680 --> 00:01:13,880 It means controllers could give you a clearance 19 00:01:13,880 --> 00:01:17,180 to fly on instruments and separate you 20 00:01:17,180 --> 00:01:19,340 from other aircraft. 21 00:01:19,340 --> 00:01:22,500 So they want you to be well separated from clouds, 22 00:01:22,500 --> 00:01:26,870 1,000 feet above, 500 feet underneath, 2,000 horizontally. 23 00:01:26,870 --> 00:01:31,700 That way, if an aircraft under IFR comes out of the clouds, 24 00:01:31,700 --> 00:01:34,550 there'll be some time for the two of you 25 00:01:34,550 --> 00:01:36,740 to see and avoid each other. 26 00:01:36,740 --> 00:01:39,960 You can see the weather minimums are different in class Golf 27 00:01:39,960 --> 00:01:41,150 airspace. 28 00:01:41,150 --> 00:01:43,670 And, actually, in uncontrolled airspace 29 00:01:43,670 --> 00:01:47,870 like up in Alaska, if you're flying on instruments, 30 00:01:47,870 --> 00:01:50,200 you don't have a clearance. 31 00:01:50,200 --> 00:01:52,170 So you'll say, well, how is that possible? 32 00:01:52,170 --> 00:01:54,462 You can be instrument rated, have an instrument capable 33 00:01:54,462 --> 00:01:57,633 airplane, and fly from airport to airport in the clouds. 34 00:01:57,633 --> 00:02:00,300 But the air traffic controllers, they can't give you a clearance 35 00:02:00,300 --> 00:02:03,450 and guarantee you separation from other aircraft 36 00:02:03,450 --> 00:02:04,830 because they don't have radar. 37 00:02:04,830 --> 00:02:06,288 They don't even have the authority. 38 00:02:06,288 --> 00:02:08,610 It's not controlled airspace. 39 00:02:08,610 --> 00:02:11,190 I've done some flying up there in little airplanes, 40 00:02:11,190 --> 00:02:13,780 and you have to be very patient. 41 00:02:13,780 --> 00:02:15,780 Another interesting thing to notice about this-- 42 00:02:15,780 --> 00:02:17,850 we'll talk about it more again later-- 43 00:02:17,850 --> 00:02:20,250 is notice how class Bravo airspace 44 00:02:20,250 --> 00:02:25,140 has lower minimums than ordinary class Echo airspace. 45 00:02:25,140 --> 00:02:30,237 So we have to be 1,000 feet from the clouds here. 46 00:02:30,237 --> 00:02:32,070 Here we just have to be clear of the clouds. 47 00:02:34,860 --> 00:02:38,340 Why are the minimums reduced right around Logan Airport 48 00:02:38,340 --> 00:02:42,558 and JFK and LAX than they are-- 49 00:02:42,558 --> 00:02:44,808 AUDIENCE: Because everyone's in contact with the tower 50 00:02:44,808 --> 00:02:47,178 so the tower knows where everyone is. 51 00:02:47,178 --> 00:02:48,720 PHILIP GREENSPUN: Yeah, great answer. 52 00:02:48,720 --> 00:02:51,720 So her answer is that air traffic control 53 00:02:51,720 --> 00:02:54,840 is in contact with everybody in class Bravo airspace 54 00:02:54,840 --> 00:02:56,183 and knows where they are. 55 00:02:56,183 --> 00:02:57,600 And in fact, they're on clearances 56 00:02:57,600 --> 00:03:00,042 in class Bravo airspace, so they're being told what to do. 57 00:03:00,042 --> 00:03:00,750 Fly this heading. 58 00:03:00,750 --> 00:03:01,860 Fly that heading. 59 00:03:01,860 --> 00:03:03,490 Maintain this altitude. 60 00:03:03,490 --> 00:03:04,740 Great answer. 61 00:03:04,740 --> 00:03:07,260 All right, so how do we know if the weather minimums are 62 00:03:07,260 --> 00:03:09,120 going to be maintained? 63 00:03:09,120 --> 00:03:12,010 Let's talk about weather theory. 64 00:03:12,010 --> 00:03:14,670 So raise your hand if you're a science major here 65 00:03:14,670 --> 00:03:16,570 as opposed to engineering? 66 00:03:16,570 --> 00:03:18,210 Where are the smart scientists? 67 00:03:18,210 --> 00:03:21,660 All right, Francis. 68 00:03:21,660 --> 00:03:24,930 So the science approach to this task 69 00:03:24,930 --> 00:03:34,160 would be to say if we could just assume that humans are only 4 70 00:03:34,160 --> 00:03:39,970 inches tall, then we could build some really great aircraft. 71 00:03:39,970 --> 00:03:42,120 And we'll get into that in a moment. 72 00:03:42,120 --> 00:03:43,100 Just think about that. 73 00:03:43,100 --> 00:03:46,570 If you're a scientist, how much flexibility 74 00:03:46,570 --> 00:03:50,440 can you have compared to being an engineer? 75 00:03:50,440 --> 00:03:55,960 All right, so let's look at the atmosphere that we do have. 76 00:03:55,960 --> 00:03:59,920 Mostly, the troposphere tops out around 40,000 feet 77 00:03:59,920 --> 00:04:02,140 according to this chart. 78 00:04:02,140 --> 00:04:05,200 And that's where most of the water vapor 79 00:04:05,200 --> 00:04:08,500 is and, therefore, most of the weather, also 80 00:04:08,500 --> 00:04:11,650 the higher temperatures. 81 00:04:11,650 --> 00:04:16,630 You can see it actually does get warm again way up high 82 00:04:16,630 --> 00:04:18,940 in the thermosphere. 83 00:04:18,940 --> 00:04:21,500 This is in kilometers on the left. 84 00:04:21,500 --> 00:04:25,550 So you can see that part of the earth that we're flying through 85 00:04:25,550 --> 00:04:30,280 is really just, I don't know, probably around 20 kilometers 86 00:04:30,280 --> 00:04:32,110 and down. 87 00:04:32,110 --> 00:04:32,990 What did I say? 88 00:04:32,990 --> 00:04:37,690 Said he could go up to 65,000 feet in this F-22. 89 00:04:37,690 --> 00:04:40,820 So that's what? 90 00:04:40,820 --> 00:04:43,830 That's a little over 10 miles. 91 00:04:43,830 --> 00:04:47,110 Yeah, it's about 20 kilometers, somewhere in that neighborhood. 92 00:04:47,110 --> 00:04:49,850 Anyway, so not too many people are going higher 93 00:04:49,850 --> 00:04:56,370 than just the bottom 0 through 20 on this chart. 94 00:04:56,370 --> 00:04:59,580 All right, who's concerned about global inequality? 95 00:04:59,580 --> 00:05:02,140 Raise your hand. 96 00:05:02,140 --> 00:05:03,440 Awesome. 97 00:05:03,440 --> 00:05:09,930 Well, you'll be pleased to know that so is the FAA. 98 00:05:09,930 --> 00:05:17,550 And this figure here shows you why it's warmer at the equator 99 00:05:17,550 --> 00:05:19,130 than up at the North Pole. 100 00:05:19,130 --> 00:05:20,880 There's the same amount-- 101 00:05:20,880 --> 00:05:24,630 we're missing a little bit of tilt here, but that's OK. 102 00:05:24,630 --> 00:05:27,090 There's the same amount of incoming solar radiation, 103 00:05:27,090 --> 00:05:30,815 but it gets spread out over a larger portion of the earth 104 00:05:30,815 --> 00:05:31,565 up near the poles. 105 00:05:34,550 --> 00:05:39,350 All right, so this is where guys like Francis have it easy. 106 00:05:39,350 --> 00:05:41,510 If you want to understand something, 107 00:05:41,510 --> 00:05:46,670 you just say, well, you know, I've got an earth, 108 00:05:46,670 --> 00:05:49,400 and it's pretty much the same as the existing earth. 109 00:05:49,400 --> 00:05:51,810 It just doesn't have any water on it. 110 00:05:51,810 --> 00:05:54,800 And it doesn't rotate, and it's not 111 00:05:54,800 --> 00:05:57,270 tilted with respect to the sun. 112 00:05:57,270 --> 00:05:58,977 So now I'll do my analysis. 113 00:05:58,977 --> 00:06:00,060 And I'll publish my paper. 114 00:06:00,060 --> 00:06:02,640 And I'll get tenure, and your problem is solved. 115 00:06:06,520 --> 00:06:07,020 Let's see. 116 00:06:07,020 --> 00:06:08,270 What would happen here? 117 00:06:08,270 --> 00:06:11,700 In a non-rotating, non-tilted waterless earth, 118 00:06:11,700 --> 00:06:14,700 it would get hotter at the equator, 119 00:06:14,700 --> 00:06:17,340 and the air would rise up from the heat. 120 00:06:17,340 --> 00:06:19,710 So we can see that here. 121 00:06:19,710 --> 00:06:23,760 So we would have low pressure right there at the equator. 122 00:06:23,760 --> 00:06:25,850 And then the air would circulate up, 123 00:06:25,850 --> 00:06:28,736 and we would have high pressure up at the polls. 124 00:06:28,736 --> 00:06:31,206 Does that makes sense to everybody? 125 00:06:31,206 --> 00:06:32,760 All right, great, problem solved. 126 00:06:32,760 --> 00:06:35,160 We can go home. 127 00:06:35,160 --> 00:06:37,940 Unfortunately, as engineers, we have 128 00:06:37,940 --> 00:06:41,130 to deal with the real world a little bit more. 129 00:06:41,130 --> 00:06:44,540 So if we're spinning around the Earth, 130 00:06:44,540 --> 00:06:49,150 We're going to end up with these three cells 131 00:06:49,150 --> 00:06:54,220 and in each hemisphere. 132 00:06:54,220 --> 00:06:56,830 And in this case, you end up still 133 00:06:56,830 --> 00:06:59,140 with a low pressure at the equator. 134 00:06:59,140 --> 00:07:02,530 But then you get a high pressure with all the air sinking down 135 00:07:02,530 --> 00:07:03,700 here. 136 00:07:03,700 --> 00:07:08,440 And you get still low pressure-- 137 00:07:08,440 --> 00:07:11,770 you still get high pressure up at the polls and low pressure 138 00:07:11,770 --> 00:07:12,310 down here. 139 00:07:18,690 --> 00:07:20,200 See if I got that right. 140 00:07:20,200 --> 00:07:22,000 High. 141 00:07:22,000 --> 00:07:23,200 I should be high. 142 00:07:23,200 --> 00:07:25,725 It says high pressure at 30 degrees North. 143 00:07:25,725 --> 00:07:27,100 Oh yeah, high, high, that's good. 144 00:07:27,100 --> 00:07:29,260 And, yes, and low and low. 145 00:07:29,260 --> 00:07:31,480 All right, we got that right. 146 00:07:31,480 --> 00:07:34,626 It gets more confusing as you see. 147 00:07:34,626 --> 00:07:37,750 OK, so the circulation-- one thing 148 00:07:37,750 --> 00:07:39,400 that the FAA wants you to know is 149 00:07:39,400 --> 00:07:42,670 that it's heat exchange that drives the weather. 150 00:07:42,670 --> 00:07:46,120 So the weather is basically a function of the sun heating up 151 00:07:46,120 --> 00:07:47,080 the earth. 152 00:07:47,080 --> 00:07:49,270 And then it's not uniform, so the heat 153 00:07:49,270 --> 00:07:53,320 gets pushed from one part of the earth to another. 154 00:07:53,320 --> 00:07:56,890 And all of this unequal heating is 155 00:07:56,890 --> 00:08:01,060 responsible for the altimeter varying, 156 00:08:01,060 --> 00:08:04,000 for wind blowing around. 157 00:08:04,000 --> 00:08:07,540 Pretty much every phenomenon that is of interest to pilots 158 00:08:07,540 --> 00:08:12,730 is caused by heat trying to move from the hotter 159 00:08:12,730 --> 00:08:16,030 parts of the earth to the colder parts of the earth. 160 00:08:16,030 --> 00:08:18,020 We'll talk a little bit more about these. 161 00:08:18,020 --> 00:08:19,870 But notice there's parts of the earth 162 00:08:19,870 --> 00:08:22,520 that are windier than others. 163 00:08:22,520 --> 00:08:26,580 Unfortunately, we're in one of the windier parts. 164 00:08:26,580 --> 00:08:33,140 OK, so you also have to know as a pilot just what an isobar is. 165 00:08:33,140 --> 00:08:35,980 That's a line of equal pressure. 166 00:08:35,980 --> 00:08:37,130 And that tells you-- 167 00:08:39,700 --> 00:08:43,539 that gives you an idea of how the wind is going to move. 168 00:08:43,539 --> 00:08:46,770 We'll see that in a minute. 169 00:08:46,770 --> 00:08:49,600 The tighter the isobars, the more dramatic 170 00:08:49,600 --> 00:08:51,720 the pressure change in a region. 171 00:08:51,720 --> 00:08:53,330 And it's the pressure gradient force 172 00:08:53,330 --> 00:08:56,240 that's causing the wind to flow from the high 173 00:08:56,240 --> 00:08:58,610 to the low pressure. 174 00:08:58,610 --> 00:09:03,150 So you might think on this chart, 175 00:09:03,150 --> 00:09:07,460 for example, that wherever you see an L and an H 176 00:09:07,460 --> 00:09:10,370 that you would just draw a vector of wind from one place 177 00:09:10,370 --> 00:09:12,110 to the other, right? 178 00:09:12,110 --> 00:09:13,950 That kind of makes sense. 179 00:09:13,950 --> 00:09:19,410 However, there is Coriolis force. 180 00:09:19,410 --> 00:09:21,232 This is for Francis, the science major. 181 00:09:21,232 --> 00:09:22,440 Francis, what course are you? 182 00:09:22,440 --> 00:09:26,328 AUDIENCE: I'm course 9, so [INAUDIBLE].. 183 00:09:26,328 --> 00:09:29,250 PHILIP GREENSPUN: Oh. 184 00:09:29,250 --> 00:09:33,210 All right, so scientists wear lab coats. 185 00:09:33,210 --> 00:09:36,360 [LAUGHTER] 186 00:09:36,360 --> 00:09:40,980 Coriolis force is a fake news force formerly known 187 00:09:40,980 --> 00:09:42,194 as fictitious. 188 00:09:46,370 --> 00:09:49,820 So you can see they're throwing the ball straight. 189 00:09:49,820 --> 00:09:54,060 But because they're on a rotating platform, 190 00:09:54,060 --> 00:09:58,430 it's apparently curving. 191 00:09:58,430 --> 00:10:00,680 So camera is mounted to the ground, 192 00:10:00,680 --> 00:10:02,360 and we'll see the ball going straight. 193 00:10:05,870 --> 00:10:08,786 They're going to draw you a little dash line at one point 194 00:10:08,786 --> 00:10:11,040 so you can see the path is actually straight. 195 00:10:17,670 --> 00:10:18,815 So the ball has an inertia. 196 00:10:18,815 --> 00:10:20,190 Basically, once it's launched, it 197 00:10:20,190 --> 00:10:22,800 wants to keep doing whatever it was doing. 198 00:10:22,800 --> 00:10:27,600 And this guy's white lab coated colleague 199 00:10:27,600 --> 00:10:29,730 just moves away from where the ball was going. 200 00:10:39,056 --> 00:10:39,556 Whoa. 201 00:10:48,240 --> 00:10:50,010 All right, everybody's got that? 202 00:10:50,010 --> 00:10:51,510 That's Coriolis force for you. 203 00:10:55,480 --> 00:10:59,620 What happens when we do this on the earth? 204 00:10:59,620 --> 00:11:00,400 So think about it. 205 00:11:00,400 --> 00:11:02,260 You have a parcel of air that's moving 206 00:11:02,260 --> 00:11:04,430 with the earth at the equator. 207 00:11:04,430 --> 00:11:07,300 If you displace it up to a higher latitude, 208 00:11:07,300 --> 00:11:11,230 it still has that velocity. 209 00:11:11,230 --> 00:11:13,690 But now the Earth isn't spinning as fast. 210 00:11:13,690 --> 00:11:19,060 So it ends up essentially moving a little bit to the right. 211 00:11:19,060 --> 00:11:22,355 That is the fundamental insight just as you saw in that video. 212 00:11:22,355 --> 00:11:24,730 You'll have to go home and think about that a little bit. 213 00:11:24,730 --> 00:11:28,240 But, basically, I think the most effective way 214 00:11:28,240 --> 00:11:31,150 to think about it is just that a parcel of air that 215 00:11:31,150 --> 00:11:34,180 was the equator wants to keep moving as if it were still 216 00:11:34,180 --> 00:11:37,460 at the equator, but it's not there anymore, 217 00:11:37,460 --> 00:11:41,170 so it moves relative to the underlying earth. 218 00:11:43,750 --> 00:11:46,420 If you combine the Coriolis force and the pressure 219 00:11:46,420 --> 00:11:50,050 gradient, then you get the actual wind direction. 220 00:11:50,050 --> 00:11:53,350 And the trend as seen here-- 221 00:11:53,350 --> 00:11:55,240 eventually, there's so much Coriolis force 222 00:11:55,240 --> 00:11:57,640 over so much time that the wind actually 223 00:11:57,640 --> 00:12:03,495 moves exactly 90 degrees to where you think it should move. 224 00:12:03,495 --> 00:12:08,920 It flows along the isobars instead of perpendicular 225 00:12:08,920 --> 00:12:10,520 across them. 226 00:12:10,520 --> 00:12:15,280 So there you have a couple pressure systems 227 00:12:15,280 --> 00:12:19,360 and you see that the wind is circulating around these lows 228 00:12:19,360 --> 00:12:23,890 and highs rather than flowing directly from one to the other 229 00:12:23,890 --> 00:12:24,670 as you'd expect. 230 00:12:27,680 --> 00:12:35,180 All right, who would like to become a helicopter test pilot? 231 00:12:35,180 --> 00:12:37,970 Raise your hand if that sounds like a fun job. 232 00:12:37,970 --> 00:12:41,900 OK, so when you're developing the manual for your Sikorsky 233 00:12:41,900 --> 00:12:44,270 helicopter, you've got to go somewhere 234 00:12:44,270 --> 00:12:46,670 where the wind is calm. 235 00:12:46,670 --> 00:12:49,340 Where would you all suggest going now 236 00:12:49,340 --> 00:12:51,693 that you've seen this chart? 237 00:12:51,693 --> 00:12:52,610 What's your name, sir? 238 00:12:52,610 --> 00:12:53,260 Sorry. 239 00:12:53,260 --> 00:12:54,020 AUDIENCE: Jeremy. 240 00:12:54,020 --> 00:12:56,560 PHILIP GREENSPUN: Jeremy, where do you want to go? 241 00:12:56,560 --> 00:12:58,550 You're going to take your Sikorsky helicopter 242 00:12:58,550 --> 00:12:59,967 and you're going to write the POH. 243 00:12:59,967 --> 00:13:01,220 AUDIENCE: [INAUDIBLE] Florida. 244 00:13:01,220 --> 00:13:02,390 PHILIP GREENSPUN: Florida. 245 00:13:02,390 --> 00:13:05,810 Sikorsky, which is headquartered in Connecticut, 246 00:13:05,810 --> 00:13:07,760 they have a big flight test facility. 247 00:13:07,760 --> 00:13:10,340 I believe it's in Palm Beach. 248 00:13:10,340 --> 00:13:12,355 So there you have it. 249 00:13:12,355 --> 00:13:15,200 They thought just along the same lines as you, 250 00:13:15,200 --> 00:13:17,540 and they'll be in the horse latitudes. 251 00:13:17,540 --> 00:13:20,150 There's a whole bunch of-- 252 00:13:20,150 --> 00:13:22,520 nobody really knows why it's called the horse latitudes. 253 00:13:22,520 --> 00:13:24,862 One idea is that the ships-- 254 00:13:24,862 --> 00:13:26,570 since there's no wind in those latitudes, 255 00:13:26,570 --> 00:13:28,340 they have to find a current, and then they 256 00:13:28,340 --> 00:13:32,950 get pulled along by the current as if they were on a horse. 257 00:13:32,950 --> 00:13:36,710 All right, surface friction is a little bit complicated. 258 00:13:36,710 --> 00:13:38,770 It tends to drag down the wind. 259 00:13:38,770 --> 00:13:44,060 You'll have to study this vector diagram on your own. 260 00:13:44,060 --> 00:13:46,300 But, really, from the FAA's point of view, 261 00:13:46,300 --> 00:13:48,130 they just want you to know mostly 262 00:13:48,130 --> 00:13:53,920 that the wind 2,000 or 3,000 feet up is 263 00:13:53,920 --> 00:13:56,200 going to be different from the wind on the surface. 264 00:13:56,200 --> 00:13:58,020 Because of surface friction, it will 265 00:13:58,020 --> 00:14:03,046 be less intense and in a slightly different direction. 266 00:14:03,046 --> 00:14:06,650 OK, vertical circulation of the air. 267 00:14:06,650 --> 00:14:10,940 I think you're going to be OK if you just remember that warmer 268 00:14:10,940 --> 00:14:12,575 air is lighter than colder air. 269 00:14:12,575 --> 00:14:14,450 That's all that you pretty much need to know. 270 00:14:17,270 --> 00:14:20,640 OK, local wind patterns. 271 00:14:20,640 --> 00:14:26,250 If you heat up the shore line, the air will rise off the shore 272 00:14:26,250 --> 00:14:28,930 and pull in air from the ocean during the daytime 273 00:14:28,930 --> 00:14:30,840 so you get that sea breeze. 274 00:14:30,840 --> 00:14:34,808 And then at nighttime, the opposite happens, 275 00:14:34,808 --> 00:14:35,850 so you get a land breeze. 276 00:14:35,850 --> 00:14:38,980 So there are some of these predictable local weather 277 00:14:38,980 --> 00:14:39,480 patterns. 278 00:14:42,240 --> 00:14:44,990 The bigger ones have to do with atmospheric stability. 279 00:14:47,520 --> 00:14:52,430 If you have a stable atmosphere, meaning 280 00:14:52,430 --> 00:14:56,120 that a displaced parcel of air tends to get pushed back down 281 00:14:56,120 --> 00:15:02,390 to wherever it was, then you get these weather characteristics 282 00:15:02,390 --> 00:15:05,480 where you're not going to be bumped around in your aircraft. 283 00:15:05,480 --> 00:15:08,360 You're going to have trouble seeing, 284 00:15:08,360 --> 00:15:11,000 and you're going to see clouds that are basically flat, 285 00:15:11,000 --> 00:15:16,670 these stratiform clouds here that you see on the right. 286 00:15:16,670 --> 00:15:18,740 If it rains, it's just going to rain all day. 287 00:15:18,740 --> 00:15:21,500 It's going to be a typical miserable New England 288 00:15:21,500 --> 00:15:25,910 day where it rains all the time, or Seattle, I guess, 289 00:15:25,910 --> 00:15:28,130 is like that as well. 290 00:15:28,130 --> 00:15:30,620 Well, what about if the air once displaced 291 00:15:30,620 --> 00:15:33,350 tends to want to keep being displaced? 292 00:15:33,350 --> 00:15:35,870 If it rises up a little bit, it keeps rising. 293 00:15:35,870 --> 00:15:38,840 Then you have these clouds with vertical development. 294 00:15:38,840 --> 00:15:42,182 And the good news is you can see really well. 295 00:15:42,182 --> 00:15:44,390 You're not going to have an obstruction to visibility 296 00:15:44,390 --> 00:15:47,720 unless you're in heavy rain. 297 00:15:47,720 --> 00:15:50,810 And the rain won't be all day, every day. 298 00:15:50,810 --> 00:15:53,930 It'll be showery, but it'll be very turbulent 299 00:15:53,930 --> 00:15:56,750 if you get into that cloud or maybe right 300 00:15:56,750 --> 00:15:58,955 underneath that cloud. 301 00:15:58,955 --> 00:16:07,200 OK, what about the profile of the atmosphere? 302 00:16:07,200 --> 00:16:10,470 Let's have a look at this. 303 00:16:10,470 --> 00:16:11,210 So on the right-- 304 00:16:14,510 --> 00:16:16,640 I wonder if this is actually my newest 305 00:16:16,640 --> 00:16:17,840 version of the presentation. 306 00:16:17,840 --> 00:16:19,010 We'll see. 307 00:16:19,010 --> 00:16:20,840 I corrected an error. 308 00:16:20,840 --> 00:16:24,380 On the right, you can see that for every 1,000 feet you go up. 309 00:16:24,380 --> 00:16:27,230 So we go from 0 to 1,000 feet up. 310 00:16:27,230 --> 00:16:30,060 The temperature is gone from 18 Celsius to 15, 311 00:16:30,060 --> 00:16:32,450 so it's lapsed by 3 degrees. 312 00:16:32,450 --> 00:16:35,981 And the dew point has gone down by half a degree. 313 00:16:35,981 --> 00:16:37,400 Does that makes sense? 314 00:16:37,400 --> 00:16:40,070 The air goes up, it's lower pressure. 315 00:16:40,070 --> 00:16:43,270 This is called an adiabatic process. 316 00:16:43,270 --> 00:16:45,710 I was not a chemistry major, but I 317 00:16:45,710 --> 00:16:50,240 think that means that we're not adding or taking away 318 00:16:50,240 --> 00:16:51,530 heat from the air. 319 00:16:51,530 --> 00:16:52,980 We're just moving it. 320 00:16:52,980 --> 00:16:57,530 So the temperature and dew point spread, 321 00:16:57,530 --> 00:16:59,240 actually does get narrower. 322 00:16:59,240 --> 00:17:02,780 You can see as we rise up to 5,000 feet that the spread has 323 00:17:02,780 --> 00:17:06,380 gone down to 2 and 1/2 degrees because the dew point is not 324 00:17:06,380 --> 00:17:10,529 falling nearly as fast as the overall temperature. 325 00:17:10,529 --> 00:17:11,404 Does that make sense? 326 00:17:11,404 --> 00:17:14,990 So I think this conceivably could be an FAA test 327 00:17:14,990 --> 00:17:21,430 question that the dry adiabatic lapse rate is 3 degrees. 328 00:17:21,430 --> 00:17:26,589 OK, then the moist air is lapsing only at 2 degrees. 329 00:17:26,589 --> 00:17:32,690 So this figure shows you going from 0 to 1,000 feet, 330 00:17:32,690 --> 00:17:36,500 and from 1 to 2,000 feet, we were dropping 331 00:17:36,500 --> 00:17:39,830 3 degrees per thousand feet. 332 00:17:39,830 --> 00:17:44,070 After that, we're dropping only 2 degrees per thousand feet. 333 00:17:44,070 --> 00:17:47,790 And once the temperature dew point spread goes to 0, 334 00:17:47,790 --> 00:17:50,050 that's when a cloud happens. 335 00:17:50,050 --> 00:17:52,900 So the air can't hold anymore water vapor. 336 00:17:52,900 --> 00:17:58,320 And when the temperature and dew point meet, 337 00:17:58,320 --> 00:18:00,055 the water vapor turns into water, 338 00:18:00,055 --> 00:18:03,200 and now you've got a cloud. 339 00:18:03,200 --> 00:18:07,690 All right, so you might ask yourself, well, 340 00:18:07,690 --> 00:18:10,540 why is this air moving at all? 341 00:18:10,540 --> 00:18:12,130 Why does it start moving? 342 00:18:12,130 --> 00:18:15,380 One thing that can start it moving is a mountain range. 343 00:18:15,380 --> 00:18:19,090 So the air gets pushed by a wind coming 344 00:18:19,090 --> 00:18:23,050 from the left side of the slide up the top of the mountain. 345 00:18:23,050 --> 00:18:27,760 And at that point, it will condense into a cloud. 346 00:18:31,470 --> 00:18:34,000 Just let you absorb that cloud here for a minute. 347 00:18:34,000 --> 00:18:35,880 Notice also that relative humidity is just 348 00:18:35,880 --> 00:18:39,340 another way of stating the temperature dew point spread. 349 00:18:39,340 --> 00:18:41,880 So here temperature and dew point are pretty close, 350 00:18:41,880 --> 00:18:44,400 10 and 15 or 15 and 10. 351 00:18:44,400 --> 00:18:47,010 So we've got relative humidity of 80%. 352 00:18:47,010 --> 00:18:50,610 Over here, they're quite far apart. 353 00:18:50,610 --> 00:18:53,760 The temperature is 23, and the dew point is minus 2. 354 00:18:53,760 --> 00:18:57,790 So the relative humidity is low. 355 00:18:57,790 --> 00:19:01,270 OK, you've heard that there's a cold front coming in 356 00:19:01,270 --> 00:19:03,040 and we have all these thunderstorms. 357 00:19:03,040 --> 00:19:03,790 Well, this is why. 358 00:19:03,790 --> 00:19:07,490 The cold air is denser than the warm air. 359 00:19:07,490 --> 00:19:09,980 So it pushes the warm air up. 360 00:19:09,980 --> 00:19:12,490 And at that point, you get clouds forming, 361 00:19:12,490 --> 00:19:14,860 and you get thunderstorms all along the line 362 00:19:14,860 --> 00:19:16,860 of the cold front. 363 00:19:16,860 --> 00:19:19,230 OK, so what if you have stable air? 364 00:19:19,230 --> 00:19:20,370 Let's have a look at this. 365 00:19:25,980 --> 00:19:26,750 You end up-- 366 00:19:30,520 --> 00:19:31,160 Let's see. 367 00:19:35,770 --> 00:19:46,390 We've gone from 0, to 1, to 2, and we're only 368 00:19:46,390 --> 00:19:48,370 dropping-- actually, we're not dropping at all. 369 00:19:48,370 --> 00:19:49,328 And then we're back up. 370 00:19:49,328 --> 00:19:50,590 This is an inversion. 371 00:19:50,590 --> 00:19:53,350 OK, so, basically, the air temperature 372 00:19:53,350 --> 00:19:56,780 is pretty constant as we go up. 373 00:19:56,780 --> 00:20:11,260 So if a parcel of air rises up into the atmosphere, 374 00:20:11,260 --> 00:20:16,330 it's not going to be warmer than the surrounding air, 375 00:20:16,330 --> 00:20:20,340 so it doesn't want to keep rising. 376 00:20:20,340 --> 00:20:22,920 OK, what if it's unstable? 377 00:20:22,920 --> 00:20:24,740 So look at this by contrast. 378 00:20:24,740 --> 00:20:26,210 The environmental air temperature 379 00:20:26,210 --> 00:20:28,790 is lapsing at a higher than standard rate. 380 00:20:31,730 --> 00:20:36,250 It's going down 4 degrees Celsius per thousand feet. 381 00:20:36,250 --> 00:20:40,810 And this parcel of air that was in equilibrium 382 00:20:40,810 --> 00:20:49,120 down at sea level is still warmer than the surrounding 383 00:20:49,120 --> 00:20:51,340 air, and, therefore, it wants to keep rising. 384 00:20:51,340 --> 00:20:53,720 Does that make sense? 385 00:20:53,720 --> 00:20:58,030 So, basically, if it goes up and it wants to keep going up, 386 00:20:58,030 --> 00:21:01,090 that's unstable and a perfect situation 387 00:21:01,090 --> 00:21:05,950 for forming thunderstorms, which we'll talk about shortly. 388 00:21:05,950 --> 00:21:09,520 Temperature inversion like we saw on that earlier slide 389 00:21:09,520 --> 00:21:14,560 where it was actually a little bit warmer here, 390 00:21:14,560 --> 00:21:21,310 that tends to keep air where it is, 391 00:21:21,310 --> 00:21:23,470 and, therefore, you end up with poor visibility 392 00:21:23,470 --> 00:21:25,660 and haze because all the stuff that's 393 00:21:25,660 --> 00:21:27,430 obscuring your visibility is just staying 394 00:21:27,430 --> 00:21:28,833 underneath the inversion. 395 00:21:28,833 --> 00:21:30,250 It's kind of a common phenomenon I 396 00:21:30,250 --> 00:21:32,800 think in some of these basins like Los Angeles. 397 00:21:32,800 --> 00:21:36,035 Talk about an inversion, and ordinary people 398 00:21:36,035 --> 00:21:38,410 think about that, and hear that term, and worry about it. 399 00:21:41,140 --> 00:21:44,680 Most frequently-- you're going to I think see this on a test 400 00:21:44,680 --> 00:21:45,570 maybe-- 401 00:21:45,570 --> 00:21:53,350 is phenomena having to do with the ground radiating back heat 402 00:21:53,350 --> 00:21:56,440 into the atmosphere or into space at night. 403 00:21:56,440 --> 00:21:58,990 Tends to make the ground cold and the air 404 00:21:58,990 --> 00:22:02,560 right next to the ground cold, whereas the air just slightly 405 00:22:02,560 --> 00:22:04,750 higher than that, a couple thousand feet up, 406 00:22:04,750 --> 00:22:07,430 hasn't changed the temperature too much. 407 00:22:07,430 --> 00:22:12,400 So the terrestrial radiation on a clear still night 408 00:22:12,400 --> 00:22:15,400 can cause a temperature inversion. 409 00:22:15,400 --> 00:22:20,380 We talked about this earlier when the temperature and dew 410 00:22:20,380 --> 00:22:26,130 point meet, and that's when the water vapor will condense. 411 00:22:26,130 --> 00:22:27,030 Frost. 412 00:22:27,030 --> 00:22:32,740 When the dew point is below freezing 413 00:22:32,740 --> 00:22:38,190 and you have a surface that's cold, then you will get-- 414 00:22:38,190 --> 00:22:40,860 maybe it's cold because it radiated its heat 415 00:22:40,860 --> 00:22:43,260 back out into space at night, for example. 416 00:22:43,260 --> 00:22:46,260 That's when you get frost forming. 417 00:22:46,260 --> 00:22:48,630 And you want to definitely clear that off your aircraft 418 00:22:48,630 --> 00:22:53,580 before you go anywhere because it messes 419 00:22:53,580 --> 00:22:58,080 with the smooth flow of the air, so the wing becomes much less 420 00:22:58,080 --> 00:23:02,220 efficient even if the shape hasn't changed that much. 421 00:23:02,220 --> 00:23:04,095 All right, let's look at the kinds of clouds. 422 00:23:07,290 --> 00:23:14,520 You've got basically-- the prefix to the cloud 423 00:23:14,520 --> 00:23:18,630 tells you what height it is. 424 00:23:18,630 --> 00:23:21,360 And then the second part of the word 425 00:23:21,360 --> 00:23:24,930 tells you kind of the shape of the cloud. 426 00:23:24,930 --> 00:23:29,430 So I'll just let you absorb this a little bit. 427 00:23:29,430 --> 00:23:34,460 If it says nimbo, yeah, cumulonimbus or nimbostratus, 428 00:23:34,460 --> 00:23:37,550 that means it's raining. 429 00:23:37,550 --> 00:23:42,260 Towering cumulus is bad if they talk about that. 430 00:23:42,260 --> 00:23:43,790 And cumulonimbus is the worst. 431 00:23:43,790 --> 00:23:48,620 That's just another fancier way of saying thunderstorm. 432 00:23:48,620 --> 00:23:53,580 OK, so here's your Latin lesson for today. 433 00:23:53,580 --> 00:23:55,200 Unfortunately, I didn't study Latin. 434 00:23:55,200 --> 00:23:57,890 It would have been nice when I went 435 00:23:57,890 --> 00:23:59,810 to Peru to be able to communicate 436 00:23:59,810 --> 00:24:05,060 with the locals in Latin America. 437 00:24:05,060 --> 00:24:06,320 OK, that wasn't funny I guess. 438 00:24:06,320 --> 00:24:09,722 [LAUGHTER] 439 00:24:12,650 --> 00:24:18,320 If you have low clouds, the main hazard to worry about 440 00:24:18,320 --> 00:24:20,180 is the icing. 441 00:24:20,180 --> 00:24:24,800 If the water is supercooled, that's the worst. 442 00:24:24,800 --> 00:24:27,717 You can usually get a forecast of that. 443 00:24:27,717 --> 00:24:29,300 You'll get AIRMETs for icing, and they 444 00:24:29,300 --> 00:24:33,545 might talk about supercooled water is a hazard. 445 00:24:36,530 --> 00:24:38,720 I guess this might be an exam question. 446 00:24:38,720 --> 00:24:43,850 Stratus clouds form when moist, stable air flows upslope. 447 00:24:43,850 --> 00:24:49,310 But just remember stable usually means the flat clouds, 448 00:24:49,310 --> 00:24:50,740 stratiform clouds. 449 00:24:50,740 --> 00:24:55,745 And unstable is where you get the cumuliform clouds. 450 00:25:02,090 --> 00:25:03,230 So same deal. 451 00:25:03,230 --> 00:25:04,880 Those altocumulus are going to be 452 00:25:04,880 --> 00:25:13,690 much more turbulent and probably more severe icing potential. 453 00:25:13,690 --> 00:25:19,390 The high clouds-- it's so cold in the high atmosphere 454 00:25:19,390 --> 00:25:22,720 that the maximum amount of water that can be stored 455 00:25:22,720 --> 00:25:25,570 is pretty low, and, therefore, you 456 00:25:25,570 --> 00:25:28,780 don't tend to get ice when it's below 457 00:25:28,780 --> 00:25:32,260 say minus 15 degrees Celsius. 458 00:25:32,260 --> 00:25:35,110 There just isn't a whole lot of moisture to begin with. 459 00:25:38,790 --> 00:25:41,910 OK, so this is what as a GA pilot 460 00:25:41,910 --> 00:25:44,608 you're more likely to have to worry about. 461 00:25:44,608 --> 00:25:46,650 You're probably not going to be up at 25,000 feet 462 00:25:46,650 --> 00:25:48,360 in your Piper Warrior. 463 00:25:48,360 --> 00:25:57,038 But you could be underneath a cumulus cloud. 464 00:25:57,038 --> 00:25:58,830 I will tell you that if you have passengers 465 00:25:58,830 --> 00:26:01,470 and there is low cumulus clouds, you desperately 466 00:26:01,470 --> 00:26:02,860 want to get above those. 467 00:26:02,860 --> 00:26:05,700 So let's say there's a bunch of cumulus clouds at 4,000 468 00:26:05,700 --> 00:26:07,290 or 5,000 feet. 469 00:26:07,290 --> 00:26:10,500 You can climb probably to 8,000 or 10,000 feet 470 00:26:10,500 --> 00:26:13,120 in a light airplane, and that'll be much, much smoother. 471 00:26:13,120 --> 00:26:16,470 So as soon as you get above the cumulus clouds, 472 00:26:16,470 --> 00:26:18,750 that's where the air tends to smooth out, 473 00:26:18,750 --> 00:26:21,180 and it'll be much more comfortable. 474 00:26:21,180 --> 00:26:23,730 But if it's a towering cumulus cloud, 475 00:26:23,730 --> 00:26:29,130 they may go up to as high as 60,000 feet down in Texas. 476 00:26:29,130 --> 00:26:30,660 And you really can't get over them 477 00:26:30,660 --> 00:26:36,870 in anything short of an SR-71 or maybe last as F-22. 478 00:26:36,870 --> 00:26:41,970 Even the latest Gulfstreams only go to 51,000, I believe. 479 00:26:41,970 --> 00:26:44,750 OK, so thunderstorms are the worst hazard. 480 00:26:44,750 --> 00:26:47,700 Even the airliners get in trouble and thunderstorms 481 00:26:47,700 --> 00:26:55,790 with hail smashing into the windshield and turbulence that 482 00:26:55,790 --> 00:26:58,930 can bend stuff. 483 00:26:58,930 --> 00:27:08,500 So how do you predict if you're flying along-- 484 00:27:08,500 --> 00:27:10,580 well, if you're preparing to go on a flight, 485 00:27:10,580 --> 00:27:12,788 how do you predict where the clouds are likely to be? 486 00:27:12,788 --> 00:27:16,130 One thing you do is look at the temperature dew point spread. 487 00:27:16,130 --> 00:27:21,255 The FAA tells you to use a lapse rate of 2.5 degrees Celsius 488 00:27:21,255 --> 00:27:22,880 to figure out where the clouds will be. 489 00:27:22,880 --> 00:27:28,240 So if there is a 10 degree temperature dew point spread, 490 00:27:28,240 --> 00:27:30,740 then you should expect the clouds to have 491 00:27:30,740 --> 00:27:32,480 a base at about 4,000 feet. 492 00:27:32,480 --> 00:27:33,780 There's a typo in the slide. 493 00:27:33,780 --> 00:27:34,760 Sorry about that. 494 00:27:34,760 --> 00:27:37,340 I thought we had the new version in the Dropbox. 495 00:27:37,340 --> 00:27:42,590 The temperature lapses at 3 for the dry adiabatic air. 496 00:27:42,590 --> 00:27:43,590 You remember that? 497 00:27:43,590 --> 00:27:45,415 And the dew point's at 0.5. 498 00:27:45,415 --> 00:27:46,790 So if we go back to that figure-- 499 00:27:52,080 --> 00:27:55,690 I think it was our-- yeah. 500 00:27:55,690 --> 00:27:59,640 Yeah, if we go back here, you remember this? 501 00:27:59,640 --> 00:28:02,530 We went from 18, to 15, to 12. 502 00:28:02,530 --> 00:28:05,260 And the dew point, meanwhile, is falling from 3, to 2 and 1/2, 503 00:28:05,260 --> 00:28:06,430 to 2. 504 00:28:06,430 --> 00:28:07,270 So that's why. 505 00:28:10,930 --> 00:28:13,060 It's 2.5 as a rule of thumb. 506 00:28:13,060 --> 00:28:16,300 That's not great, but you can actually-- 507 00:28:16,300 --> 00:28:19,843 Just look at METARs around the country, 508 00:28:19,843 --> 00:28:21,760 and I think you will see because they give you 509 00:28:21,760 --> 00:28:24,130 the basis of the clouds and the ceilings. 510 00:28:24,130 --> 00:28:26,260 I think you usually will see that it's 511 00:28:26,260 --> 00:28:31,810 reasonably close to this formula but almost never spot on. 512 00:28:31,810 --> 00:28:38,620 OK, this is worth studying. 513 00:28:38,620 --> 00:28:41,300 I'm not going to cover it completely here. 514 00:28:41,300 --> 00:28:44,540 But some of these are exam questions. 515 00:28:44,540 --> 00:28:46,420 Advection fog-- I think I remember 516 00:28:46,420 --> 00:28:50,590 they like to ask about that, when the warm moist air moves 517 00:28:50,590 --> 00:28:55,253 over a cool surface along coastlines. 518 00:28:55,253 --> 00:28:56,420 So I think that makes sense. 519 00:28:56,420 --> 00:28:58,520 Maybe that's what they're having in California 520 00:28:58,520 --> 00:28:59,650 a lot of the time. 521 00:28:59,650 --> 00:29:05,455 They have the fog over the coastal areas. 522 00:29:12,270 --> 00:29:15,810 And radiation fog-- also, in the Western deserts, 523 00:29:15,810 --> 00:29:18,850 oftentimes, there's fog in the morning. 524 00:29:18,850 --> 00:29:23,160 So I think you're advection fog would be a coastal phenomenon. 525 00:29:23,160 --> 00:29:26,520 And the radiation fog, something they 526 00:29:26,520 --> 00:29:32,750 can have in a place like Arizona or Palm Springs. 527 00:29:32,750 --> 00:29:36,610 OK, the FAA loves this. 528 00:29:36,610 --> 00:29:39,880 If you see ice pellets, you probably shouldn't be flying. 529 00:29:39,880 --> 00:29:44,110 But they want you to know that if you do see ice pellets, 530 00:29:44,110 --> 00:29:47,260 how did they arrive? 531 00:29:47,260 --> 00:29:50,050 Well, they had to be freezing rain up higher. 532 00:29:50,050 --> 00:29:52,360 So don't climb in hopes of getting out of the ice 533 00:29:52,360 --> 00:29:56,050 pellets because then you'll have freezing rain on your airplane 534 00:29:56,050 --> 00:29:58,960 which is probably the worst kind of icing-related hazard. 535 00:30:01,580 --> 00:30:04,170 OK, airmasses. 536 00:30:09,470 --> 00:30:10,790 You can just have a look here. 537 00:30:13,560 --> 00:30:16,460 If you hear that there's a polar airmass coming in, 538 00:30:16,460 --> 00:30:18,800 it's going to be cold, not too exciting. 539 00:30:18,800 --> 00:30:19,890 Might be a question. 540 00:30:19,890 --> 00:30:21,650 Fronts, they do want you to see-- 541 00:30:21,650 --> 00:30:23,970 be able to read one of these maps. 542 00:30:23,970 --> 00:30:25,910 They may occasionally asked you a question. 543 00:30:25,910 --> 00:30:29,090 So one thing to remember is the cold front 544 00:30:29,090 --> 00:30:32,260 has the pointy spikes like icicles. 545 00:30:32,260 --> 00:30:36,140 So if you can remember that, you'll be pretty good. 546 00:30:36,140 --> 00:30:39,410 There's a cold front. 547 00:30:39,410 --> 00:30:44,690 Again, you can just read this and study it at your leisure. 548 00:30:48,115 --> 00:30:49,740 I guess they might want you to remember 549 00:30:49,740 --> 00:30:54,950 that the front is the boundary between two air masses. 550 00:30:54,950 --> 00:30:55,560 OK. 551 00:30:55,560 --> 00:30:57,440 Here's a typical drawing where they'll 552 00:30:57,440 --> 00:30:59,420 show you the cold fronts and the warm fronts. 553 00:31:03,070 --> 00:31:05,188 When there is a front, how do you 554 00:31:05,188 --> 00:31:06,730 know when the front has gone through? 555 00:31:06,730 --> 00:31:10,000 Well, the temperature's changed and the wind's changed, 556 00:31:10,000 --> 00:31:10,750 simple as that. 557 00:31:14,020 --> 00:31:18,250 Here's a little explanation of what you can expect 558 00:31:18,250 --> 00:31:20,860 when a cold front goes through. 559 00:31:32,800 --> 00:31:35,792 Everybody is happy with that? 560 00:31:35,792 --> 00:31:37,610 OK. 561 00:31:37,610 --> 00:31:43,030 When a warm front goes through, it gets warmer afterwards. 562 00:31:43,030 --> 00:31:46,520 Yeah, so the warm front produces, as you can see, 563 00:31:46,520 --> 00:31:53,332 light to moderate rain, drizzle, visibility is bad. 564 00:31:53,332 --> 00:31:55,040 That's actually the important thing here. 565 00:31:55,040 --> 00:31:56,960 The visibility gets poor. 566 00:31:56,960 --> 00:31:59,760 And then it becomes fair and haze, 567 00:31:59,760 --> 00:32:06,887 whereas the visibility becomes really good after a cold front 568 00:32:06,887 --> 00:32:07,470 comes through. 569 00:32:11,850 --> 00:32:16,984 Occluded fronts-- same deal, bad visibility. 570 00:32:19,720 --> 00:32:20,220 All right. 571 00:32:20,220 --> 00:32:21,400 Let's talk about hazards. 572 00:32:21,400 --> 00:32:23,200 This is more important. 573 00:32:23,200 --> 00:32:34,940 So this is a summary of where heat 574 00:32:34,940 --> 00:32:39,860 is released into the atmosphere versus absorbed by water. 575 00:32:39,860 --> 00:32:48,650 So as the water goes, for example, from vapor to liquid, 576 00:32:48,650 --> 00:32:50,145 it releases heat. 577 00:32:50,145 --> 00:32:51,770 So that's exactly what's happening when 578 00:32:51,770 --> 00:32:54,170 it's raining in a thunderstorm. 579 00:32:56,870 --> 00:33:00,590 And that's not a good thing. 580 00:33:00,590 --> 00:33:01,550 All right. 581 00:33:01,550 --> 00:33:08,390 So here's the FAA's chart of a cumulus cloud forming. 582 00:33:08,390 --> 00:33:11,480 So you can see the lapse rate over here 583 00:33:11,480 --> 00:33:14,270 in the ambient atmosphere. 584 00:33:14,270 --> 00:33:19,550 It's going from 28 to 24 down to 21. 585 00:33:19,550 --> 00:33:25,070 So it is, at least initially, higher 586 00:33:25,070 --> 00:33:27,050 than standard lapse rate. 587 00:33:27,050 --> 00:33:30,450 So this warm air-- 588 00:33:30,450 --> 00:33:31,820 it starts at 28. 589 00:33:31,820 --> 00:33:34,280 And then it drops only to 25. 590 00:33:34,280 --> 00:33:36,830 So it's still warmer than the surrounding air. 591 00:33:36,830 --> 00:33:42,930 So it goes into becoming this big, nasty cloud. 592 00:33:42,930 --> 00:33:47,270 There's this-- you can see-- if you don't 593 00:33:47,270 --> 00:33:49,880 want to look at the summaries of weather forecasts, 594 00:33:49,880 --> 00:33:54,170 you can look at these shards of lifted index. 595 00:33:54,170 --> 00:33:59,510 Here, it shows the difference between minus 18 and minus 11, 596 00:33:59,510 --> 00:34:00,200 minus 7. 597 00:34:00,200 --> 00:34:03,898 That gives you a measure of the thunderstorm potential. 598 00:34:03,898 --> 00:34:04,940 There are charts of that. 599 00:34:08,900 --> 00:34:12,620 But as pilots, this is more what we 600 00:34:12,620 --> 00:34:14,750 deal with on our practical day-to-day basis. 601 00:34:14,750 --> 00:34:16,760 We just look at the next rad data 602 00:34:16,760 --> 00:34:20,130 from the radar stations that are strewn around the country. 603 00:34:20,130 --> 00:34:22,287 And if it's red, we try to find a path around it, 604 00:34:22,287 --> 00:34:23,870 because there's just not much else you 605 00:34:23,870 --> 00:34:26,659 can do in a little aircraft. 606 00:34:26,659 --> 00:34:31,520 It's possible that you could get over this entire front 607 00:34:31,520 --> 00:34:35,570 if you were in a jet that could climb up 608 00:34:35,570 --> 00:34:37,610 to 40,000 feet or higher. 609 00:34:37,610 --> 00:34:40,397 But in a Piper or Cessna or Cirrus, 610 00:34:40,397 --> 00:34:42,230 you're just not going to be able to do that. 611 00:34:45,719 --> 00:34:46,350 OK. 612 00:34:46,350 --> 00:34:51,560 The thunderstorm lifecycle-- this is, I think, 613 00:34:51,560 --> 00:34:52,850 my favorite test question. 614 00:34:52,850 --> 00:34:54,650 How do you know that the thunderstorm 615 00:34:54,650 --> 00:34:56,600 has reached its mature stage? 616 00:34:56,600 --> 00:35:00,230 Well, it's raining, simple as that. 617 00:35:00,230 --> 00:35:03,300 If it's raining, it's mature. 618 00:35:03,300 --> 00:35:09,640 If it's dissipating, you're going to get these downdrafts. 619 00:35:09,640 --> 00:35:12,040 If it's building, you get updrafts. 620 00:35:12,040 --> 00:35:17,720 So everything comes up, and then it all comes down. 621 00:35:17,720 --> 00:35:19,490 OK. 622 00:35:19,490 --> 00:35:22,267 Look at that nasty thunderstorm. 623 00:35:22,267 --> 00:35:24,350 You're going to get turbulence right on top of it. 624 00:35:24,350 --> 00:35:27,630 If you can clear that thunderstorm by 5,000 feet, 625 00:35:27,630 --> 00:35:29,520 it'll probably nice and smooth. 626 00:35:29,520 --> 00:35:33,272 So this is your good argument for a plane that can go to 51 627 00:35:33,272 --> 00:35:35,690 [INAUDIBLE] or 510. 628 00:35:35,690 --> 00:35:37,020 Airliners don't go that high. 629 00:35:37,020 --> 00:35:41,640 The latest these jets go much higher than airliners. 630 00:35:41,640 --> 00:35:42,630 All right. 631 00:35:42,630 --> 00:35:44,190 The hazard-- we're going to hear more 632 00:35:44,190 --> 00:35:47,190 about this tomorrow from [? Dojo, ?] 633 00:35:47,190 --> 00:35:49,950 from the Brazilian Air Force. 634 00:35:49,950 --> 00:35:59,190 But there is this chart here that shows you how much load 635 00:35:59,190 --> 00:36:00,290 factor-- that's in g's. 636 00:36:03,650 --> 00:36:09,200 If you're going pretty fast, you can pretty quickly 637 00:36:09,200 --> 00:36:12,350 get into the structural damage range. 638 00:36:15,030 --> 00:36:19,020 So that's why they tell you-- this these lines here are 639 00:36:19,020 --> 00:36:19,860 basically-- 640 00:36:23,560 --> 00:36:26,200 this is how many g's you can get on the aircraft 641 00:36:26,200 --> 00:36:29,800 with either extreme movements on the controls 642 00:36:29,800 --> 00:36:32,470 or extreme movements that are imposed on you 643 00:36:32,470 --> 00:36:34,450 by a thunderstorm or something. 644 00:36:34,450 --> 00:36:37,450 So the takeaway from this diagram 645 00:36:37,450 --> 00:36:40,840 is slow down if you get into heavy turbulence, 646 00:36:40,840 --> 00:36:45,630 because then the airplane will stall before it bends. 647 00:36:45,630 --> 00:36:51,650 And stalling can be corrected by pushing the nose down. 648 00:36:51,650 --> 00:36:52,150 OK. 649 00:36:52,150 --> 00:36:54,580 So these are all of the hazards from thunderstorms. 650 00:36:54,580 --> 00:36:57,710 Again, it's a lot better-- 651 00:36:57,710 --> 00:36:59,710 in this day and age, there's so much information 652 00:36:59,710 --> 00:37:02,440 out there and datalink available in the cockpit 653 00:37:02,440 --> 00:37:05,890 that going through thunderstorms is just much less common 654 00:37:05,890 --> 00:37:07,060 than it used to be. 655 00:37:07,060 --> 00:37:11,860 And therefore, don't really have to remember too much, other 656 00:37:11,860 --> 00:37:15,330 than don't fly through a thunderstorm. 657 00:37:15,330 --> 00:37:18,390 Microburst-- however, if you're trying to land and beat 658 00:37:18,390 --> 00:37:20,465 the thunderstorm, you can actually 659 00:37:20,465 --> 00:37:21,840 get into a little bit of trouble, 660 00:37:21,840 --> 00:37:28,380 because the wind right before a thunderstorm or right 661 00:37:28,380 --> 00:37:36,890 after can be pretty squirrelly and cause you some difficulties 662 00:37:36,890 --> 00:37:39,350 here. 663 00:37:39,350 --> 00:37:39,850 Let's see. 664 00:37:39,850 --> 00:37:41,040 What do we have? 665 00:37:41,040 --> 00:37:43,330 So here, this airplane is getting a performance boost 666 00:37:43,330 --> 00:37:45,580 from a strong headwind. 667 00:37:45,580 --> 00:37:48,040 Now, not much is happening, except that it's 668 00:37:48,040 --> 00:37:53,270 getting pushed down, maybe faster than the airplane can 669 00:37:53,270 --> 00:37:54,200 climb. 670 00:37:54,200 --> 00:37:57,110 And at this point, you're getting a performance reduction 671 00:37:57,110 --> 00:37:58,145 from this big tailwind. 672 00:37:58,145 --> 00:38:00,520 So that's reducing-- you might think, well, that's great. 673 00:38:00,520 --> 00:38:02,390 I'm getting pushed along with a tailwind. 674 00:38:02,390 --> 00:38:05,810 But if it's suddenly taking away your airspeed, 675 00:38:05,810 --> 00:38:09,920 then that's not a performance boost. 676 00:38:09,920 --> 00:38:10,670 All right. 677 00:38:10,670 --> 00:38:16,280 So the thunderstorm emergency procedures 678 00:38:16,280 --> 00:38:18,320 are, again, probably a little bit 679 00:38:18,320 --> 00:38:20,090 less relevant now that we're living 680 00:38:20,090 --> 00:38:27,380 in this world of constant datalink and NEXRAD data. 681 00:38:27,380 --> 00:38:31,850 2006, there was a famous accident with a former test 682 00:38:31,850 --> 00:38:34,580 pilot, Scott Crossfield, who maybe 683 00:38:34,580 --> 00:38:38,180 didn't get the best advice from air traffic control. 684 00:38:38,180 --> 00:38:44,060 And I don't think he had datalink in his cockpit. 685 00:38:44,060 --> 00:38:46,400 The Boeing B 29 bomber crews, they would fly, 686 00:38:46,400 --> 00:38:51,800 I think, seven or eight hours from an island in the Pacific 687 00:38:51,800 --> 00:38:53,090 over to Japan. 688 00:38:53,090 --> 00:38:55,040 And during those eight hours, they 689 00:38:55,040 --> 00:38:59,140 had satellite data, no data from a ground station. 690 00:38:59,140 --> 00:39:01,390 So they just had no idea what they were going through. 691 00:39:01,390 --> 00:39:03,620 And they didn't go as high as the designers thought 692 00:39:03,620 --> 00:39:06,770 that airplane was designed to go, super high. 693 00:39:06,770 --> 00:39:09,083 But they were so loaded up with fuel and bombs, 694 00:39:09,083 --> 00:39:11,000 they couldn't practically climb all that high. 695 00:39:11,000 --> 00:39:15,410 So they were going at 10-15,000 feet over the ocean. 696 00:39:15,410 --> 00:39:20,300 And at those altitudes, you can't really see-- 697 00:39:20,300 --> 00:39:22,820 you may get into an embedded thunderstorm. 698 00:39:22,820 --> 00:39:27,140 Today's airliners, they go so high that you really are never 699 00:39:27,140 --> 00:39:29,600 in a position where you blunder into stuff, 700 00:39:29,600 --> 00:39:33,240 or almost never, because you're in the clear, 701 00:39:33,240 --> 00:39:35,300 and you can just see the towering cumulus 702 00:39:35,300 --> 00:39:36,480 and not fly there. 703 00:39:36,480 --> 00:39:40,290 You just back yourself around them. 704 00:39:40,290 --> 00:39:42,600 So I guess-- yeah, the final statement 705 00:39:42,600 --> 00:39:44,640 there is, get-there-itis hasn't been cured. 706 00:39:44,640 --> 00:39:48,000 So as a pilot, the safest thing you can do 707 00:39:48,000 --> 00:39:50,850 is really fight that tendency to want 708 00:39:50,850 --> 00:39:52,740 to complete the mission as planned 709 00:39:52,740 --> 00:39:55,230 and overcommit to your plan of action. 710 00:39:55,230 --> 00:39:57,330 All right. 711 00:39:57,330 --> 00:40:02,010 There are three other categories of turbulence to worry about. 712 00:40:02,010 --> 00:40:13,540 Probably the worst is due to terrain, like mountains. 713 00:40:13,540 --> 00:40:18,340 This low level turbulence from thermals is not crazy. 714 00:40:18,340 --> 00:40:21,430 But as I said, if you get above the clouds, that plane on top 715 00:40:21,430 --> 00:40:25,190 is going to be in a nice, smooth air. 716 00:40:25,190 --> 00:40:28,920 Wake turbulence [INAUDIBLE] is also another thing to consider. 717 00:40:28,920 --> 00:40:30,270 Let's look at that. 718 00:40:30,270 --> 00:40:42,120 So if you're taking off behind an airplane, so look at that-- 719 00:40:42,120 --> 00:40:45,120 heavy, slow and in clean configuration. 720 00:40:45,120 --> 00:40:50,220 So airplanes will tend to retract their flaps, 721 00:40:50,220 --> 00:40:52,590 and therefore be in a clean configuration 722 00:40:52,590 --> 00:40:55,080 shortly after takeoff, whereas, if they're landing, 723 00:40:55,080 --> 00:40:56,112 the flaps are down. 724 00:40:56,112 --> 00:40:58,320 They're not generating quite as much wake turbulence. 725 00:40:58,320 --> 00:41:01,500 Although, still if you land behind a Boeing, in your little 726 00:41:01,500 --> 00:41:02,850 Cessna, you will notice that. 727 00:41:07,190 --> 00:41:09,500 The solution here-- and I think this 728 00:41:09,500 --> 00:41:13,190 is a test question-- is you land or take off 729 00:41:13,190 --> 00:41:17,220 beyond the touchdown point of a large aircraft. 730 00:41:17,220 --> 00:41:21,870 So if the large aircraft-- 731 00:41:21,870 --> 00:41:26,820 let's say the large aircraft landed right here in front 732 00:41:26,820 --> 00:41:28,380 of the laptop on the runway. 733 00:41:28,380 --> 00:41:30,510 You just fly a little bit higher. 734 00:41:30,510 --> 00:41:33,290 And you land maybe in the middle of the runway. 735 00:41:33,290 --> 00:41:36,000 And that way, you can't possibly get into wake turbulence, 736 00:41:36,000 --> 00:41:38,880 because it will have sunk below that big aircraft's flight 737 00:41:38,880 --> 00:41:39,840 path. 738 00:41:39,840 --> 00:41:41,270 Controllers at a towered airport, 739 00:41:41,270 --> 00:41:45,210 they'll also separate you by the necessary number of minutes. 740 00:41:45,210 --> 00:41:48,810 They have a bunch of regulations about how much separation 741 00:41:48,810 --> 00:41:51,630 they have to have between aircraft. 742 00:41:51,630 --> 00:41:53,500 And then similarly, for liftoff point-- 743 00:41:53,500 --> 00:41:56,790 so if the big airplane-- 744 00:41:56,790 --> 00:42:01,290 again, this is not really that much of a practical problem, 745 00:42:01,290 --> 00:42:04,320 because so little runway is used by light airplanes. 746 00:42:04,320 --> 00:42:08,610 But if the big airplane rotated and took off and started 747 00:42:08,610 --> 00:42:11,280 climbing here, well, then you take off 748 00:42:11,280 --> 00:42:13,740 and start climbing earlier. 749 00:42:13,740 --> 00:42:16,187 Of course, the climb rate of the big airplane 750 00:42:16,187 --> 00:42:17,770 is probably a lot better than you are. 751 00:42:17,770 --> 00:42:20,460 So you've got to think about which way the wind is going 752 00:42:20,460 --> 00:42:23,290 and maybe try to turn away from it. 753 00:42:23,290 --> 00:42:25,710 I've only really been stuck in weight turbulence 754 00:42:25,710 --> 00:42:27,540 once that I can think about. 755 00:42:27,540 --> 00:42:29,040 It was at Hanscom Field. 756 00:42:29,040 --> 00:42:32,100 And there was a heavy helicopter that 757 00:42:32,100 --> 00:42:34,080 was cleared to land on the runway, 758 00:42:34,080 --> 00:42:36,090 and then transitioned sideways. 759 00:42:36,090 --> 00:42:37,292 And I was in the Cirrus. 760 00:42:37,292 --> 00:42:39,000 And I think the controllers didn't really 761 00:42:39,000 --> 00:42:42,800 think about, well, how much wake turbulence can 762 00:42:42,800 --> 00:42:44,640 a helicopter generate. 763 00:42:44,640 --> 00:42:46,530 So I was trying to land. 764 00:42:46,530 --> 00:42:49,110 And maybe about 200 feet above the ground, 765 00:42:49,110 --> 00:42:53,820 there was a sharp wing dip that I-- 766 00:42:53,820 --> 00:42:57,180 the good news is you don't have to be heroic to correct it, 767 00:42:57,180 --> 00:42:59,490 because, if your airplane is banked, 768 00:42:59,490 --> 00:43:02,050 the natural tendency is to want to take the bank out. 769 00:43:02,050 --> 00:43:03,630 So whenever your natural tendency 770 00:43:03,630 --> 00:43:09,430 is to do the safe thing, that's usually not much of a problem. 771 00:43:09,430 --> 00:43:09,930 Oh yeah. 772 00:43:09,930 --> 00:43:13,753 So anyway, here's the FAA question. 773 00:43:13,753 --> 00:43:14,920 Who wants to give an answer? 774 00:43:14,920 --> 00:43:15,580 Shout it out. 775 00:43:15,580 --> 00:43:16,360 A, B, or C? 776 00:43:24,160 --> 00:43:25,553 AUDIENCE: A. 777 00:43:25,553 --> 00:43:26,470 PHILIP GREENSPUN: Yay. 778 00:43:30,620 --> 00:43:31,680 All right. 779 00:43:31,680 --> 00:43:36,330 So this is a practical issue, especially for anybody 780 00:43:36,330 --> 00:43:39,960 who wants to fly out west. 781 00:43:39,960 --> 00:43:41,790 You have the Sierra Mountains. 782 00:43:41,790 --> 00:43:44,100 You have the Rocky Mountains. 783 00:43:44,100 --> 00:43:46,680 And you have to be very careful when crossing these mountain 784 00:43:46,680 --> 00:43:49,530 ranges. 785 00:43:49,530 --> 00:43:52,770 If the wind aloft forecast is more than about 30 knots 786 00:43:52,770 --> 00:43:56,130 for the time that you're planning on crossing, 787 00:43:56,130 --> 00:43:59,640 you can expect this kind of turbulence on the lee side 788 00:43:59,640 --> 00:44:02,680 or the eastern side of those mountain ranges. 789 00:44:02,680 --> 00:44:07,200 So when I've crossed those mountains in light airplanes, 790 00:44:07,200 --> 00:44:11,100 I have usually done it first thing in the morning basically. 791 00:44:11,100 --> 00:44:15,420 So I arranged to shut down just short of the mountains 792 00:44:15,420 --> 00:44:18,330 the night before, and then cross early in the morning 793 00:44:18,330 --> 00:44:21,330 when the winds are typically calm. 794 00:44:21,330 --> 00:44:25,470 So you can look for these lenticular clouds. 795 00:44:25,470 --> 00:44:27,690 But again, if you saw the winds aloft 796 00:44:27,690 --> 00:44:30,660 forecast that it was going to be blowing 50 knots at 12,000 797 00:44:30,660 --> 00:44:32,580 feet, you can be pretty sure that it's 798 00:44:32,580 --> 00:44:36,580 going to be turbulent. 799 00:44:36,580 --> 00:44:37,080 All right. 800 00:44:37,080 --> 00:44:43,610 Structural icing-- you can get rime, clear or mixed. 801 00:44:43,610 --> 00:44:47,720 I'll just let you look through the conditions that 802 00:44:47,720 --> 00:44:48,380 lead to this. 803 00:44:56,300 --> 00:45:00,350 Clearing rime-- probably rime icing is more common. 804 00:45:04,470 --> 00:45:06,760 What happens? 805 00:45:06,760 --> 00:45:09,713 Everything gets worse about your aircraft. 806 00:45:09,713 --> 00:45:11,130 Especially if you're on autopilot, 807 00:45:11,130 --> 00:45:15,890 it's a challenge to recognize when icing is occurring. 808 00:45:15,890 --> 00:45:18,070 You can be in the air, fat, dumb, and happy 809 00:45:18,070 --> 00:45:22,110 while the airplane gets iced up. 810 00:45:22,110 --> 00:45:27,870 So the worst part of it, I guess, is that you can't climb. 811 00:45:27,870 --> 00:45:30,720 Basically, when your airplane has all this performance 812 00:45:30,720 --> 00:45:34,630 reduction, you can summarize this all-- 813 00:45:34,630 --> 00:45:38,070 if it's only moderate icing, basically you 814 00:45:38,070 --> 00:45:39,570 have an aircraft that can't climb. 815 00:45:39,570 --> 00:45:41,130 All you can do is descend. 816 00:45:41,130 --> 00:45:45,900 So a good practical tip is, if you're-- well, first off all, 817 00:45:45,900 --> 00:45:47,760 the good news is, if you're a VFR pilot, 818 00:45:47,760 --> 00:45:49,620 like you guys are going to become, 819 00:45:49,620 --> 00:45:52,020 initially you shouldn't have to worry about icing, 820 00:45:52,020 --> 00:45:55,200 because it's a phenomenon that occurs when you're in a cloud. 821 00:45:55,200 --> 00:45:57,840 So you shouldn't be in a cloud if you're a VFR pilot 822 00:45:57,840 --> 00:45:58,820 to begin with. 823 00:45:58,820 --> 00:46:01,110 So how did you get ice? 824 00:46:01,110 --> 00:46:03,300 The exception might be freezing rain, if you somehow 825 00:46:03,300 --> 00:46:05,410 drive through freezing rain. 826 00:46:05,410 --> 00:46:08,370 But if you are instrument-rated and you are going somewhere-- 827 00:46:08,370 --> 00:46:12,960 I'm planning on going to New York next week in the Cirrus. 828 00:46:12,960 --> 00:46:19,350 So if it's cloudy, even if there's no icing forecast, 829 00:46:19,350 --> 00:46:22,620 I know that there is a risk of getting ice on the wings. 830 00:46:22,620 --> 00:46:25,885 So in the wintertime, I just say, 831 00:46:25,885 --> 00:46:28,260 well look, I'm not going to go unless it's above freezing 832 00:46:28,260 --> 00:46:30,900 on the surface, because, if I get iced up, 833 00:46:30,900 --> 00:46:36,330 then inadvertently I need an escape route. 834 00:46:36,330 --> 00:46:40,200 And if it's going to be above freezing at, say, 3,000 feet, 835 00:46:40,200 --> 00:46:41,340 well, that's fine. 836 00:46:41,340 --> 00:46:43,710 I know that I probably won't be able to climb 837 00:46:43,710 --> 00:46:48,060 if I get moderate icing, but I will be able to descend. 838 00:46:48,060 --> 00:46:49,920 Even a brick can descend. 839 00:46:49,920 --> 00:46:53,087 So descend down to 3,000 feet, and all the ice will melt off. 840 00:46:53,087 --> 00:46:53,920 That would be great. 841 00:46:53,920 --> 00:46:56,780 But if it's below freezing on the surface, 842 00:46:56,780 --> 00:47:00,610 then it's basically a no-go. 843 00:47:00,610 --> 00:47:02,310 I've definitely had icing a few times. 844 00:47:02,310 --> 00:47:03,360 And it's pretty scary. 845 00:47:03,360 --> 00:47:09,470 I was out on a day when with an instrument student. 846 00:47:09,470 --> 00:47:11,270 And it seemed like a perfect day to go 847 00:47:11,270 --> 00:47:13,700 practice instrument flying. 848 00:47:13,700 --> 00:47:15,530 There was no turbulence. 849 00:47:15,530 --> 00:47:17,840 There was just clouds everywhere, 850 00:47:17,840 --> 00:47:19,747 about 800 feet of ceiling. 851 00:47:19,747 --> 00:47:21,830 So you could be in the clouds, do real approaches, 852 00:47:21,830 --> 00:47:25,190 get experience with actual IMC. 853 00:47:25,190 --> 00:47:27,920 And halfway through the flight, I 854 00:47:27,920 --> 00:47:31,970 started criticizing this guy for using way too much power. 855 00:47:31,970 --> 00:47:35,990 The power settings were all off. 856 00:47:35,990 --> 00:47:37,142 What are you doing wrong? 857 00:47:37,142 --> 00:47:38,600 And then I looked out on the wings. 858 00:47:38,600 --> 00:47:40,520 And I saw they were all frosted. 859 00:47:40,520 --> 00:47:42,020 So we descended. 860 00:47:42,020 --> 00:47:46,280 We managed to complete an ILS approach into Lawrence 861 00:47:46,280 --> 00:47:50,750 and pulled the airplane into a warm hangar 862 00:47:50,750 --> 00:47:53,640 and got it warmed up. 863 00:47:53,640 --> 00:47:55,790 So actually, as we were as we were flying, 864 00:47:55,790 --> 00:47:58,480 the FAA issued an AIRMET for icing, 865 00:47:58,480 --> 00:48:01,370 but the controllers never told us about it. 866 00:48:01,370 --> 00:48:02,600 All right. 867 00:48:02,600 --> 00:48:04,370 Requirements for icing formation-- 868 00:48:08,040 --> 00:48:12,570 near freezing temperatures, minus 10 to 0, is the worst. 869 00:48:12,570 --> 00:48:16,080 You have to have a surface on which the ice can form. 870 00:48:16,080 --> 00:48:18,750 And you have to be invisible moisture, basically. 871 00:48:18,750 --> 00:48:22,530 So again, if you're flying in the clear with your VFR pilot 872 00:48:22,530 --> 00:48:25,510 certificate, icing should not be a factor for you. 873 00:48:30,310 --> 00:48:30,810 Yeah. 874 00:48:30,810 --> 00:48:34,860 So as I said below, go through a cold cloud 875 00:48:34,860 --> 00:48:37,910 only if you have an escape route of warm air below. 876 00:48:42,050 --> 00:48:46,550 AUDIENCE: [INAUDIBLE] for the engine [INAUDIBLE] 877 00:48:46,550 --> 00:48:51,502 as far as getting the icing in the carburetor [INAUDIBLE].. 878 00:48:51,502 --> 00:48:52,460 PHILIP GREENSPUN: Yeah. 879 00:48:52,460 --> 00:48:55,960 So the question is, what about icing in the engine? 880 00:48:55,960 --> 00:48:58,810 So you can get carb ice that we talked about. 881 00:48:58,810 --> 00:49:02,490 You can get carb ice when it's 50 degrees outside, 882 00:49:02,490 --> 00:49:05,220 as long as it's humid. 883 00:49:05,220 --> 00:49:07,440 So it's slightly unrelated. 884 00:49:07,440 --> 00:49:10,350 The main problem with engines is that you 885 00:49:10,350 --> 00:49:12,400 can get ice in the induction. 886 00:49:12,400 --> 00:49:15,930 So if the intake for the engine where it's trying to breathe 887 00:49:15,930 --> 00:49:19,260 gets iced over, then there's an alternate-- again, 888 00:49:19,260 --> 00:49:21,870 they're relying on the hero pilot. 889 00:49:21,870 --> 00:49:24,990 Some airplanes actually, it'll just open automatically, 890 00:49:24,990 --> 00:49:27,870 the vacuum of trying to suck the air through the intake that's 891 00:49:27,870 --> 00:49:32,180 not working will cause some backup door to open. 892 00:49:32,180 --> 00:49:33,930 And a lot of-- 893 00:49:33,930 --> 00:49:38,310 most IFR-certified aircraft have an alternate air lever that you 894 00:49:38,310 --> 00:49:44,380 can pull and have air pulled from somewhere inside the-- 895 00:49:44,380 --> 00:49:47,430 it's a little more protected inside the airframe. 896 00:49:47,430 --> 00:49:49,280 Does that answer your question? 897 00:49:49,280 --> 00:49:49,900 AUDIENCE: Yes. 898 00:49:49,900 --> 00:49:54,290 So I guess you're saying as long as the heat's working 899 00:49:54,290 --> 00:49:56,723 your [INAUDIBLE]. 900 00:49:56,723 --> 00:49:58,390 PHILIP GREENSPUN: As long as which heat? 901 00:49:58,390 --> 00:50:03,873 AUDIENCE: [INAUDIBLE] 902 00:50:03,873 --> 00:50:05,290 PHILIP GREENSPUN: You're not going 903 00:50:05,290 --> 00:50:07,660 to get carb icing and airframe icing at the same time 904 00:50:07,660 --> 00:50:08,230 probably. 905 00:50:08,230 --> 00:50:11,535 I think, at that point, it's probably too cold. 906 00:50:11,535 --> 00:50:12,410 I'm not I'm not sure. 907 00:50:12,410 --> 00:50:14,530 Well, the other issue is you're probably not going 908 00:50:14,530 --> 00:50:16,420 to fly a carburated airplane into the clouds, 909 00:50:16,420 --> 00:50:19,600 because the real IFR airplanes that people use to travel, 910 00:50:19,600 --> 00:50:23,340 like Cirruses and Bonanzas and stuff, 911 00:50:23,340 --> 00:50:26,910 in challenging conditions, those are almost all fuel injected. 912 00:50:26,910 --> 00:50:29,410 But you do have to worry about induction icing, like I said. 913 00:50:32,310 --> 00:50:32,810 OK. 914 00:50:35,740 --> 00:50:37,640 Icing layers are usually pretty thin. 915 00:50:37,640 --> 00:50:41,050 So if you're in a jet, you just add power and climb up 916 00:50:41,050 --> 00:50:44,390 another few thousand feet and you're out of it. 917 00:50:44,390 --> 00:50:47,560 Again, one of the effects of icing 918 00:50:47,560 --> 00:50:51,940 is to dramatically reduce your climb performance. 919 00:50:51,940 --> 00:50:55,030 So this best approach of climbing out of it 920 00:50:55,030 --> 00:50:56,440 is not always available. 921 00:51:00,380 --> 00:51:05,800 You will end up using more power on the final approach. 922 00:51:05,800 --> 00:51:09,460 And you'll add speed as well, because the stall 923 00:51:09,460 --> 00:51:10,480 speed may have gone up. 924 00:51:10,480 --> 00:51:14,530 And you can't really be sure, since it hasn't 925 00:51:14,530 --> 00:51:18,170 been quantified and tested. 926 00:51:18,170 --> 00:51:20,830 You probably won't use flaps. 927 00:51:20,830 --> 00:51:24,670 And you'll not make severe turns. 928 00:51:24,670 --> 00:51:28,870 So there's a good NASA video that I encourage you to watch, 929 00:51:28,870 --> 00:51:34,150 especially as you work on higher performance aircraft and IFR. 930 00:51:34,150 --> 00:51:37,460 NASA has this great video about icing. 931 00:51:37,460 --> 00:51:38,410 OK. 932 00:51:38,410 --> 00:51:41,830 How do the transportation class airplanes handle this? 933 00:51:41,830 --> 00:51:46,990 One approach is to push antifreeze out onto the wings. 934 00:51:46,990 --> 00:51:48,370 That used to be called TKS. 935 00:51:48,370 --> 00:51:51,040 Now, it's called CAV. 936 00:51:51,040 --> 00:51:52,460 It's just a brand name. 937 00:51:52,460 --> 00:51:55,540 So if you go to a flight school and you see a modern Cirrus, 938 00:51:55,540 --> 00:51:58,510 like the SR22s, the leading edges of the wings 939 00:51:58,510 --> 00:51:59,710 will be metal. 940 00:51:59,710 --> 00:52:01,660 And they'll have little tiny holes in them. 941 00:52:01,660 --> 00:52:05,140 And that's for this antifreeze to come out. 942 00:52:05,140 --> 00:52:08,650 If you have a very light jet or a turbo prop, 943 00:52:08,650 --> 00:52:12,250 you may have rubber boots on the wings and on the tail surfaces. 944 00:52:12,250 --> 00:52:15,310 And those inflate to crack the ice off. 945 00:52:15,310 --> 00:52:18,190 The jets are really the ultimate-- 946 00:52:18,190 --> 00:52:22,780 the bigger jets all have bleed air. 947 00:52:22,780 --> 00:52:24,220 Remember, the jets are compressing 948 00:52:24,220 --> 00:52:27,060 air so much that it becomes really hot even before it's 949 00:52:27,060 --> 00:52:28,030 burned. 950 00:52:28,030 --> 00:52:30,490 So you pull the bleed air off the compressor, 951 00:52:30,490 --> 00:52:34,550 and you run it out into the leading edges of the wings. 952 00:52:34,550 --> 00:52:37,720 And that just melts the ice off. 953 00:52:37,720 --> 00:52:46,150 The transporter aircraft, they also heat the windshields. 954 00:52:46,150 --> 00:52:47,890 So you'll be able to see when you do-- 955 00:52:47,890 --> 00:52:50,920 if it's not above freezing at the airport, 956 00:52:50,920 --> 00:52:54,580 you'll have a clear windshield, so you can leave the runway. 957 00:52:54,580 --> 00:52:58,390 Even in very basic airplanes like a Cirrus, 958 00:52:58,390 --> 00:53:03,040 if they're IFR-certified, the pedo tube 959 00:53:03,040 --> 00:53:04,180 is going to be heated. 960 00:53:04,180 --> 00:53:06,740 There will be pedo heat. 961 00:53:06,740 --> 00:53:08,810 OK. 962 00:53:08,810 --> 00:53:11,630 You can learn a whole bunch more about this. 963 00:53:11,630 --> 00:53:13,310 I think everything you know to pass 964 00:53:13,310 --> 00:53:15,440 the test is pretty much in the Pilot's Handbook 965 00:53:15,440 --> 00:53:17,390 of Aeronautical Knowledge. 966 00:53:17,390 --> 00:53:20,120 There's a little bit in the AIM. 967 00:53:20,120 --> 00:53:23,480 If you want to dig deeper and understand more of it, 968 00:53:23,480 --> 00:53:26,150 then I would encourage you to look at these FAA weather 969 00:53:26,150 --> 00:53:27,790 publications. 970 00:53:27,790 --> 00:53:31,940 One is about weather theory and one is about information 971 00:53:31,940 --> 00:53:34,280 that you can get from various sources. 972 00:53:34,280 --> 00:53:38,450 There's also these videos that I would encourage you to look at. 973 00:53:38,450 --> 00:53:41,830 One of them is called "Ambushed by Ice" 974 00:53:41,830 --> 00:53:44,390 and "Into Deep--" these particular links, 975 00:53:44,390 --> 00:53:47,300 don't write those down, because I fixed them last night, 976 00:53:47,300 --> 00:53:49,490 but the Dropbox didn't update yet. 977 00:53:49,490 --> 00:53:52,500 Do they have real-time weather data? 978 00:53:52,500 --> 00:53:55,700 So the question is, in your basic trainer airplane, 979 00:53:55,700 --> 00:53:58,770 do they have real-time weather data? 980 00:53:58,770 --> 00:54:02,300 So let's just talk about East Coast Aero Club 981 00:54:02,300 --> 00:54:07,010 is a typical higher end flight school. 982 00:54:07,010 --> 00:54:10,430 About maybe 10 years ago, almost all the aircraft 983 00:54:10,430 --> 00:54:15,050 had a Garmin IFR-certified GPS put in, a Garmin 430. 984 00:54:15,050 --> 00:54:18,770 So at that point, you had a really good GPS. 985 00:54:18,770 --> 00:54:22,700 But they did not have XM weather pulling data from satellites, 986 00:54:22,700 --> 00:54:25,670 which we'll talk about in a little bit, 987 00:54:25,670 --> 00:54:30,710 because it's a $500 a year subscription and a $10,000 box. 988 00:54:30,710 --> 00:54:32,990 So people didn't want to do it. 989 00:54:32,990 --> 00:54:37,220 With ADS-B, the FAA is now providing some of the same data 990 00:54:37,220 --> 00:54:41,240 that XM was providing for free, as long 991 00:54:41,240 --> 00:54:44,380 as you have an ADS-B in transponder. 992 00:54:44,380 --> 00:54:47,720 And the East Coast Aero-- well, everybody 993 00:54:47,720 --> 00:54:50,780 has to upgrade to ADS-B by 2020. 994 00:54:50,780 --> 00:54:52,940 Not everybody has to have ADS-B in, 995 00:54:52,940 --> 00:54:54,800 but I think East Coast Aero Club's probably 996 00:54:54,800 --> 00:54:57,830 fairly typical of the better flight schools. 997 00:54:57,830 --> 00:55:00,980 They've put-- or they're gradually putting in a ADS-B 998 00:55:00,980 --> 00:55:03,600 in and out transponders in all their aircraft. 999 00:55:03,600 --> 00:55:05,487 It won't display in the cockpit. 1000 00:55:05,487 --> 00:55:07,820 You'll have to have your phone, your iPad, or something. 1001 00:55:07,820 --> 00:55:11,180 But you'll be able to see-- 1002 00:55:11,180 --> 00:55:13,460 you'll be able to see NEXRAD radar picture. 1003 00:55:13,460 --> 00:55:15,110 You'll be able to get METARs and TAFs. 1004 00:55:15,110 --> 00:55:16,280 You'll get all of that. 1005 00:55:16,280 --> 00:55:16,940 So I think-- 1006 00:55:16,940 --> 00:55:20,120 TINA: But if you don't want to rely on someone else-- 1007 00:55:20,120 --> 00:55:21,440 this is MIT. 1008 00:55:21,440 --> 00:55:23,960 You can actually get that data yourself. 1009 00:55:23,960 --> 00:55:26,810 So when we talk about weather data today, 1010 00:55:26,810 --> 00:55:28,310 we're going to also talk about how 1011 00:55:28,310 --> 00:55:34,160 you can do it yourself, build your own Stratux ADS-B 1012 00:55:34,160 --> 00:55:35,670 receiver. 1013 00:55:35,670 --> 00:55:36,930 And I've actually done this. 1014 00:55:36,930 --> 00:55:38,340 It was really fun to do. 1015 00:55:38,340 --> 00:55:41,210 It's very easy, actually. 1016 00:55:41,210 --> 00:55:45,260 Basically, based on a Raspberry Pi with a couple of antennas, 1017 00:55:45,260 --> 00:55:48,740 with a little cooling fan, you can build a little box that 1018 00:55:48,740 --> 00:55:50,750 can receive that weather data. 1019 00:55:50,750 --> 00:55:53,610 And it actually-- the software is open source. 1020 00:55:53,610 --> 00:55:55,820 And it can sync with your other tools. 1021 00:55:55,820 --> 00:55:58,280 So I have it synced with my Foreflight app. 1022 00:55:58,280 --> 00:56:00,490 So when I'm flying, I plug that in, I 1023 00:56:00,490 --> 00:56:02,030 bring a backup battery for it. 1024 00:56:02,030 --> 00:56:05,420 And it gives me weather data and some other traffic data. 1025 00:56:05,420 --> 00:56:07,573 And we'll be talking about that in a couple hours. 1026 00:56:07,573 --> 00:56:09,490 PHILIP GREENSPUN: Yeah, I should have noticed. 1027 00:56:09,490 --> 00:56:12,560 As Tina said, a lot of flight school customers 1028 00:56:12,560 --> 00:56:15,650 for the last five years would bring little battery powered 1029 00:56:15,650 --> 00:56:21,300 boxes and stick them to the windshield of whatever they're 1030 00:56:21,300 --> 00:56:21,800 flying. 1031 00:56:21,800 --> 00:56:24,920 And they would get a whole bunch of more modern services. 1032 00:56:24,920 --> 00:56:26,780 I personally don't love that. 1033 00:56:26,780 --> 00:56:28,720 When I started out in my flying career, 1034 00:56:28,720 --> 00:56:30,470 I had my big flight bag with all the stuff 1035 00:56:30,470 --> 00:56:32,330 I was going to bring into the airplane. 1036 00:56:32,330 --> 00:56:34,427 And now, I have the philosophy that I 1037 00:56:34,427 --> 00:56:36,260 don't want to bring anything into the CIrrus 1038 00:56:36,260 --> 00:56:37,430 other than a pencil. 1039 00:56:37,430 --> 00:56:41,140 I want everything that I need to be in the panel. 1040 00:56:41,140 --> 00:56:44,150 But yeah, I definitely think, in the older airplanes, 1041 00:56:44,150 --> 00:56:45,950 it's become conventional for people 1042 00:56:45,950 --> 00:56:52,090 to bring some sort of ADS-B receiver and get that data.