A science lesson

Last weekend, as Matt and I were driving through the neighborhood, he asked me if I knew why some roofs had snow on top of them and some didn't.

I've always assumed it had something to do with the angle of the sun. That sounds about right, wouldn't you think?

Wrong.

Maybe I'm the only one who doesn't know this, but the real reason has everything to do with the second law of thermodynamics, which states that energy goes from high to low.

Or, in other words, your house doesn't get cold because you "let the cold air in." It gets cold because heat leaves it whenever it has the opportunity to do so.

The homes in this picture were primarily built in the 1940s and weren't insulated very well. Therefore, the parts of the roofs in this picture without any snow are over small attic bedrooms with poor insulation, and the heat escapes and melts the snow. The parts of the roofs that do have snow are over unused and unheated portions of the upstairs, maybe even storage nooks or closets.

Now I'll never look at snowcovered roofs in the same way again. I'm glad I know the real reason for the phenomenon, although there is a part of me that still wants to believe it has a little something to do with the angle of the sun.