A Cloud of Uncertainty

As an asthmatic child that missed a lot of school and didn’t play in many sports, I had to find truly innovative ways to geek out. I checked out the same dinosaur book from the library so many times that my first grade teacher just gave it to me one day. I wrote my own books, albeit near complete plagiarism, on chemistry and astronomy. And in an attempt to combine my geekdom with my love for the sports I couldn’t play, I created an entire league of dinosaur football teams, meticulously setting up all the yard markers and providing play-by-play for my audience of me. Cue sad music.

One other thing that has fascinated me since I can remember is weather. And within that, I continue to be mesmerized by clouds. I was still pretty young when I started to memorize all the different types – stratus, cumulus, cirrus, nimbus, cumulonimbus, cirrocumulus, altostratocumulocirrus… ok I may have made that last one up. My PhD thesis (CU Boulder – go Buffs!) was in large part about teaching a machine to categorize clouds in satellite imagery. As a postdoc (College Park, Maryland – go Terps!), I signed up to participate in a science outreach event with local kids – and so of course I created a big poster of all the different cloud types. My favorite scientific paper ever – by a landslide – was about how artists had portrayed clouds in paintings throughout history. Yeah, I like clouds.

In the last post, we explored the complex interactions between the Earth and it’s atmosphere with respect to temperature and photons – a discussion scientists typically refer to as the radiation budget. But we didn’t give a moment’s consideration to clouds, and their impact is profound. As many types of clouds as there are, the radiation budget only cares about two broad categories: clouds that cool us down, and clouds that warm us up.

The clouds that cool us down are typically thick – from space they look white, because they are reflecting the Sun’s photons back up upward, preventing them from reaching the lower atmosphere or us. The clouds that heat us up are typically thin (usually wispy cirrus) – they let a lot of the Sun’s photons in, but then they block the infrared photons from us and our atmosphere from getting back out.

Sounds pretty straightforward, right? But think about how fast clouds develop, move, and dissipate, and then extrapolate that to days upon weeks upon months upon years – it’s really hard to figure out what the overall effect is. The end result is that we have a lot of uncertainty surrounding clouds and their effects on how temperatures vary across the Earth and over time.

People don’t like uncertainty. We want things to be black or white, yes or no, left or right, innie or outie, pineapple on pizza is genius or pineapple on pizza is Satan incarnate. We don’t like gray area. We want things to be settled, so we can move from step A, which is now done, to step B. How the hell can we move to step B if we haven’t answered step A with 100 percent surety?

There are few ways in which we are sillier as a species than in our desperate need for certainty (and along with that, our utter disdain for uncertainty). Nowhere are we sillier in our need for certainty than in the case of weather. It has become part of our culture to state in beer hall conversations that the weather people can never get the forecast right. And yet, they get it right an overwhelming percentage of the time. It’s just that we only remember the occasions when they are wrong. And yet, even when they are wrong, it is mostly about whether rain turned to snow, or if one particular spot got hit a little harder than another. How often do you get a blizzard when the forecast was sunny skies? Even our predictions of hurricane tracks are pretty damned good, Sharpies notwithstanding. The uncertainty is rarely about whether a big event is going to occur, it’s more about exactly when and exactly where the effects will be exactly this or exactly that.

Why can’t we get it all right down to that very last detail? Because just like our radiation budget is ultimately governed by the actions of unimaginably tiny photons, the circulation of air and heat in our atmosphere is ultimately governed by the actions of unimaginably tiny molecules, and we don’t know where all those molecules are to begin with, much less where they will end up a minute, an hour, or a couple of days from now. But why are we so brutal to our weather forecasters? Predictions about what’s going to happen to our economy are even more imperiled. How did all those predictions about the last Presidential election go? Why aren’t you a millionaire from having successfully predicted the outcomes of all the football games last season? Uncertainty rules the world. It is not a weakness of any particular endeavor, it is a fact of life. And in the case of weather and climate, a big part of that uncertainty can be traced back to clouds.

But if we knew everything that was going to happen, all of the time, what would be the point of free will? We would just be making decisions that we would have no other choice but to make. Clouds are the spice of life. A toast, to Habanerocumulus.

I don’t know about you, but I see a T-Rex returning a pick six.

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