The Radius of a Rainbow

The city that I now call home is located in a sub-Arctic desert, which mostly means we need to run humidifiers in the winter to keep the cat fur from sticking to the walls with all the static, and in the summer, we are largely spared the spectacular, but kind of frightening, thunder and lightning storms I grew up with in hot, humid Montreal.

Global warming however, means shifting weather patterns, and over the past couple of summers, we have slowly but surely been having more thunderstorms. Tonight's however, was even more spectacular than normal, if crazy weather can be seen to be "normal" at all.

It started around 4 p.m., when I could see a sheet of charcoal grey stretching from the horizon up into the equally somber clouds in the North sky. Over the next couple of hours, those clouds rolled in, until the entire sky was charcoal grey. And then those clouds opened, and for roughly an hour the rain pelted down, bouncing off the pavement like nickels, piercing the screen door until the entire patio door track was filled with water, and obscuring my view across the street.

When the rains finally slowed however, I saw something I don't remember ever seeing before - a double rainbow tracing a full 180 degrees in the sky, the inner rainbow almost incandescent, the colours were so vivid. I will always regret not having a camera to capture this astounding sight, but I stood there on the deck of the sailing club for several minutes, watching it fade and shift, even remarking at one point that it was being reflected in the lake, it was so intense. A handful of other people attending the same workshop also stepped outside to take it in while it lasted, and we were commenting about how you usually only see one end of a rainbow, and the arc tends to disappear into a cloud or fade away, and that this was something else entirely.

I was thinking the arc of this particular rainbow was perfectly circular, not stretched out the way they sometimes are, and then I thought, for no particular reason, what is the radius of a rainbow?

I'm pretty sure someone like Descartes has done the math, and figured out the complicated principles of refraction and distance, and the size of the water droplets probably matters too, but somehow all the science diminishes the sheer perfection of nature's beauty, this big, bright, multicoloured arc stretching from the North sky to the South over the massive dark lake, even for a moment shining back up at itself.

And then, like so many other things in nature, it was gone, obscured once more by another wave of rain.