Rain Failure

Now, there's no reason on earth for mosquitos to exist, so anything that kills them should be considered useful. Except unless political speeches were fatal to ol' Mr. and Mrs. Anopheles, because the itch of a mosquito bite will end and speeches...well, won't.

You'd think that rain might be a good way wipe out some of the little bloodsuckers, but it turns out that's not the case. Although mosquitos are very tiny and raindrops have quite a bit of velocity built up, what with falling from the sky and all, the hoped-for happy result of rain smashing the critters into their deserved oblivion doesn't happen.

Some scientists at Georgia Tech tried to figure out why this was so. Were mosquitos that good at dodging the raindrops? Did they find ways to seek shelter before the rain got too heavy for them to fly around in it? What was the reason?

Turns out it's more a matter of simple physics. Mosquitos are indeed small, and by comparison many raindrops are large. But when a mosquito in mid-air is hit by one of the raindrops, its very smallness helps it survive. Being small, it doesn't slow the raindrop down very much, and when a moving object's momentum isn't affected very much by an impact, very little of the kinetic energy that momentum built up is transferred to whatever it hit. The 10 percent slowdown a mosquito makes for a raindrop when it's hit means the mosquito's body only absorbs 10 percent of the built-up kinetic energy of the raindrop, and that's not enough to squash them in midair.

The same principle is behind the way two eggs will break if you smash one into the other. Unless there's some weakness in the moving egg's shell, the egg that's sitting still will almost always be the one that breaks. The kinetic energy of the moving egg is transferred to the stationary one, and that breaks its shell. Those five metal balls hanging on small swings work the same way. When one is pulled back and allowed to fall into the other four, it strikes them with all its kinetic force. They four balls together have a greater mass than the one ball by itself, so the moving single ball stops. But the other four are on swings as well, so the transferred kinetic energy pushes them away. Then they swing back, and so on and so on.

And I suppose there's a benefit to skeeters surviving rain showers. The little things are so repugnant that causing their deaths with the flat of my hand is a satsifaction I'm not 100% sure I'd care to lose.