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Wednesday, October 28, 2015

Weather pictures speak a thousand words, Part 2: Weather hazards

Part 1 had lots of pictures of air masses demonstrating how much the atmosphere flows like water. This time, let's see what happens when the weather misbehaves.


The problem with ice isn't, as many pilots think, that it adds a lot of weight. In reality, it doesn't weigh all that much compared to the enormous performance penalty it creates by changing the shape and/or smoothness of the wing surface. After all, how efficient would your wing be if it were made from rock candy?

That nub on the windshield wiper is put there specifically to ice up. That way you can easily see if you're picking up ice, since it's right in your field of view--unlike the wings.


Some days, you have no choice but to dodge towering cumulus clouds:

At least there was a gap between those. Here's something you don't want to see sitting right over your initial approach fix:

Sure, thunderstorms are pretty when you're sitting on the ground:

They're not so pretty when you're trying to get from one airport to another, however. This is a classic frontal line, where a cold front plows through, lifting the air ahead of it and creating a long line of thunderbumpers:

And this (like the first thunderstorm picture above) one is a classic air mass or "pop-up" thunderstorm. It's easy to identify because it's all by itself:

In What do beer and thunderstorms have in common? I wrote about what helps a pocket of convection build into a monster like this. If there isn't enough energy to create something like the big guy above, you might end up with a failed thunderstorm that never happened, like this:

You can tell from the wispiness of the cloud that it tried to get going but fizzled out. (Not surprisingly, as I took that picture at 7:12 a.m. before the heat of the day added enough fuel to the atmospheric fire. There were thunderstorms there later that afternoon.) However, if there is enough energy to get the convection ball rolling, you end up with something like the next four pictures, each taken two minutes apart:

See how fast that grew? In less than eight minutes, it went from a little puff to a decently-growing towering cumulus. If I'd have had a chance to take more, you probably would have seen it keep growing even more. It's almost like a bomb going off, which is what this pocket of convection looked like:

That's why in the post Why there is no reason to fly through a thunderstorm in peacetime I compared the average thunderstorm's power and an atomic bomb's power.

Ever wonder what rain would look like if you could see it from the side instead of having it fall directly on your head? On the ground, you can't do that, but from the air you see it all the time. It's the misty stuff in these pictures:

And here you can see some virga, which is rain that evaporates before making it to the ground:

Here I am getting rained on while above the clouds! Why? Because there's another layer above me:

But as the day goes on and the sun begins to set, the ground begins to cool and more energy isn't being fed into the convection system anymore. Things begin to calm down and die out:

Even when it's cruddy on the ground, it can be beautiful above. Check out next week's post for how pretty it can be once you blast through the gray on the ground.

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The author is an airline pilot, flight instructor, and adjunct college professor teaching aviation ground schools. He holds an ATP certificate with a DHC-8 type rating, as well as CFI, CFII, MEI, AGI, and IGI certificates, and is a Master-level participant in the FAA's WINGS program and a former FAASafety Team representative. He is on Facebook as Larry the Flying Guy, has a Larry the Flying Guy YouTube channel, and is on Twitter as @Lairspeed.

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