I recently wrote about being fascinated by clouds. This fascination is something I’ve always had, and it doesn’t seem to have lessened over the years. If anything, it’s become stronger.
More than a decade ago, I stood in a hotel room in Minneapolis and watched a tiny smear of a cloud appear, grow, shrink, and finally disappear completely from an otherwise clear blue sky. As I watched it fade, I thought of the opening of Arthur C. Clarke’s Against the Fall of Night. I still wonder why it appeared at all, especially since its lifespan was so brief. If its existence was so tenuous to begin with, why did it ever exist?
On a recent flight from Minneapolis to Cedar Rapids, Iowa, our Saab 340 propeller plane nosed between and just over a series of wispy clouds. I love looking at clouds from the air, particularly when they’re close enough to make out the fine structural details. These were particularly complex, consisting of tangles of vaporous filaments that stretched and merged like pulled cotton.
Clouds mystify me. What is it that causes one part of the air to contain a cloud, and another to be clear? Put another way, what defines the edge of clouds, particularly the filamentary ones like those through which we flew?
At the macro level, of course, some atmospheric conditions simply don’t favor cloud formation. The micro level is where I have the questions. Once a cloud starts to form, what keeps it from continuing to grow until it fills the entire sky, or at least the entire vicinity? As we flew over Iowa toward Detroit, there was a scattering of small, roundish clouds near the ground. What caused them to form where they did, and why did they stay small and round? Why didn’t they smear out, or build up in mass? Another good example are the summer clouds that rapidly scoot through a clear sky on days that are not particularly humid. The wind doesn’t rip these clouds apart, and they don’t seem either to grow or shrink. What conditions formed them? What holds them so firmly together?
As a child, I once ran out into a windy rain storm to look at the storm clouds overhead. I stared straight up and saw a massive cloud wall stretching up into the haze and high-level rain, and in that moment I could almost feel the boundaries of the cold front as it swept over our house. As a senior in high school, I watched a late-afternoon thunderstorm move away, bisecting the sky into dark gray and a profound golden glow that I can still scarcely believe existed. I kept trying to understand how this combination could happen even as I thrilled at its existence.
I once thought seriously about studying for a career in meteorology, and this fascination is most of the reason why.