Monday, November 20, 2006

SNOW!!!



You have to look real hard in these pictures, but the little white streaks are snow flurries that one of our reporters shot with his Palm phone tonight. Yes, the flakes were flying today west of Atlanta in Bremen and Carrollton and then this evening, many folks called in to say that they were seeing flurries in Midtown Atlanta! Whenever this happens, many people ask me, "How can it be snowing when its not 'cold enough'"? The answer is "cold enough" where? Its true, our ground temperature never reached 32, the freezing mark. However, it has certainly been that cold in the air several thousand feet above the ground, where the clouds are. And that's where it counts.

You see, freezing temperatures at the ground only allow the falling snow to stick to the ground. During the afternoon today, the freezing line was about 5000 feet above the ground. But during the evening, the freezing level lowered to just about 1000 feet above the ground. So imagine you're a snowflake coming out of the cloud. You only have a short distance to go before you reach the ground. The time it takes for you to fall 1000 feet isn't enough to allow you to either melt or evaoprate. Depending on how dry the air is close to ground, the flake will hold together until it hits the ground, where the air is above 32 degrees and it melts.

The pool of cool air that has settled in over us, though is a fairly rare phenomenon, known as a "cut-off" low. It is a circulation of cold air that has become "cut-off" from the main jet stream. The jet stream is a band of high-speed, high-altitude winds that circle the globe and move weather systems around. The cut-off low is similar to what would happen if you dropped a heavy ball into a steadily-moving stream. The ball would settle into the stream and unless the current picked up, the ball wouldn't move. So it is with the cut-off low. Its stuck until the jet stream shifts or changes position to dislodge it. If we didn't have the cut-off low, we would have never seen the flurries because the air above the ground wouldn't have gottne cold enough.

Now that you've heard me ramble about the "why", just enjoy the "what" the next time it happens. Snow is rare in these parts and it always allows us a momentary distraction from life's demands to reveal life's beauty.

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