Picture of the day - December 26, 2006

Frost And Fog

My granddaughter Olivia was hoping for a white Christmas this year, but she didn't get one. What she got instead was a white Christmas Eve thanks to a combination of heavy frost and thick fog. (But if you ask her I'm sure she'll tell you that it was a poor substitute!) Fog and frost are among nature's most interesting phenomena. Fog is created when the air cools to the point where it can no longer hold all of the water vapor contained within it, causing a portion of the water vapor to condense into water droplets which remain suspended in the air. The temperature at which this condensation occurs is called the dew point. As for frost, many people believe that it is formed when dew freezes, but that isn't the case. Frost is created when the earth's surface (and anything on it such as grass) cools to a temperature that is below freezing while the dew point temperature is near or above freezing. The condensing water immediately sticks to the surface (or grass, or cars...) in the form of ice without bothering to pass through the liquid phase. This transformation from a gas (water vapor) directly into a solid (ice) is called sublimation. Of course Olivia couldn't care less about any of this. She just wanted a snowy white Christmas and she didn't get one, but the frosty and foggy Christmas Eve we had was a pretty sight nonetheless!   Submit a photo of your own! Picture of the day archives