Aftermath

Yesterday, we got 2½ inches of rain at our house as a cold (relatively speaking) front came through. The forecast high for today is about 10° cooler, and the humidity has really dropped.

All that rain meant that our fence got really soaked. That fence is situated so that it is hit by the sun pretty early in the morning as the sun comes up, and since it is a dark (though faded) color, it heats up pretty quite a bit rather fast.

And this is the result:

Steam Rising (click for larger image)

What we see here is the sunlight heating the water on the fence and evaporating it. It is that visible because I’m shooting right into the sun and because it is an absolutely still morning. Even a bit of a breeze would dissipate it too much.

This reminds me of something that happened in my 8^th grade science class. We had just learned from the teacher that water vapor (the gaseous state of water) was colorless and transparent. “What,” then, we wanted to know, “were we seeing coming out of tea kettles?” Unfortunately, the science teacher had no idea, and could only fall back on what the book said, that water vapor was colorless and transparent. We were unconvinced.

What we see here (and at a tea kettle) are miniscule droplets of liquid water. After leaving the hot fence as a gas, the water recondenses in the cooler air, so what we are seeing is the light scattering off the liquid/gas boundary. This, of course, is also what clouds are made of.