Thursday, October 8, 2009

Frost On The Pumpkin

Yes indeed, it is cold out there this morning. What was interesting this morning was the display of atmospheric physics that was right in front of our noses. As I drove down from Spokane's South Hill into the Latah Valley below the temperature on the car thermometer read 37 degrees as I started down, and plummeted to 28 when I got to the bottom. That was just about 8 o'clock this morning. This is living proof that as the air cools the air molecules get closer together, causing the density to increase. This causes that cold air to slide down the side of the hill and fill in the valleys, much like soup poured into a bowl occupies the bottom of the bowl and fills from there. Minus a good breeze the coldest air fills the valleys at night and early in the mornings. That is why my tomato plants bit the big one last night, while those of the Laborers For Christ, down at the church site, succumbed to the elements about a month ago. There you have it, a little lesson in microclimatology! The official low at the airport this morning was 29 degrees, the coldest it has been so far this fall.

Looking ahead there is not much to look forward to after today, at least if you don't like really cold temperatures. After reaching the upper 50s today, we very likely won't see the plus side of 50, let alone 60, until early next week. The wind will be picking up tomorrow putting an extra bite into the cold, to the tune of 15 to 25 miles per hour. That will put wind chill factors in the 20s and 30s through the day. The weekend should be sunny to partly cloudy, with light winds, but still much colder than normal for the middle of October. Highs will only be in the mid to upper 40s, and overnight temperatures will be dipping, dropping, diving, to the mid teens to low 20s. Thats brrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrisk!

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