Rain in central Mexico during the dry season, between November and May, is not common, but not impossible. When it comes, it often doesn’t last for long, serving only to wash some of the dust off the streets and tempt the locusts into singing in anticipation of an early rainy season.

This photo was taken 20 minutes after sunset, and the lens was open for 302 seconds, creating the dreamy blurring of the water, which was being battered by raindrops, and the clouds, which were being blown slowly over five minutes from the left to the right of the frame.

Taking an exposure this long requires a bit of patience. First you have to get the exposure dialed in correctly at a normal shutter speed. Then, the scene already composed and focused in the viewfinder, screw on the 10-stop neutral density filter. Next, multiply the normal shutter speed by 10 or so, probably adding on another stop to account for the rapidly fading light, keeping in mind that for every full stop of exposure you wish you add, you must double the length of the exposure.

Then, if it’s raining, cover the camera and your head with your jacket, as if you were Ansel Adams poised in 1942 atop a large-format camera, and sit there for 302 seconds, counting each one because, of course, you forgot your watch at home.