Spotted Towhee in the rain at Cooper Mountain Nature Park, Beaverton, Oregon on 15 June 2010 by Greg Gillson.
Since we're in the second day of above-90 degree temperatures, my mind began to drift back to the cool rainy days of spring when we thought summer would never come. In other words, just two weeks ago.
I was birding up at the new Cooper Mountain Nature Park on a hill south of Beaverton, Oregon. During our hike it started sprinkling a bit. The towhees didn't seem to mind, singing away. [Click for previous blog posts on Spotted Towhees.]
In this photo you can see the raindrops, as streaks, frozen in time. Exactly 1/160th of a second, to be precise, according to the camera settings. OK, my mind churns, the towhee is about 8 inches long and the raindrop streak looks to be approximately one inch long. Distance divided by Time equals Rate, according to algebra learned some time between the 5th and 8th grade. Thus, 1 inch divided by 1/160th of a second equals 160 inches per second, or... 9.1 miles per hour!
A quick Google! search for "how fast does rain fall?" leads me to several sites where I learn that a raindrop falls 5 to 18 miles per hour. Any faster and the raindrop breaks apart and slows down. File that trivia away for the next time conversation drags at your party!
[This post has been rewritten on 12 July 2010. Thanks to Mike Patterson for helping me correct my math errors on the earlier post.]