Friday, March 27, 2009

Perihelion





According to the calendar Spring has arrived, although you wouldn't know it from the chilly temperatures here. My thermometer read a chilly -37C when I awoke this morning. While I don't know the exact science behind it, I believe it has to do with the fact that the sun (and we get plenty of that now) heats up the upper atmosphere enough so that the underlying layer of colder air is forced down closer to the ground. Warmer temperatures appear to be just around the corner though judging from the forecast. At any rate, the thin cloud cover today produced a rather large halo (called a perihelion I believe) around the sun which made for a dazzling view from my classroom window this afternoon.

2 comments:

Visiting nerd said...

It's called a 22° circle and two parhelia. Perihelion is when the earth is closest to the sun, which happens in early January.

Way Way Up said...

Thanks for the clarification. They are quite interesting phenomena!