Sunday was the 60th anniversary of the coldest day ever recorded in Madison: January 30, 1951. The temperature that day reached an astounding 37 degrees below zero.
To get that cold, a lot of circumstances have to be in place. First, a fresh and relatively deep snow cover is a great help as snow radiates infrared energy exceptionally well. With the long nighttime hours of mid-winter, by the end of the night, a lot of energy has been radiated away from the surface of the snow, chilling the air just above it...
Second, crystal clear nights are needed to maximize the amount of energy loss near the surface... The calm winds prohibit vertical mixing of the air, again working toward keeping the near surface temperature as cold as possible. In fact, on the morning of January 30, the air temperature about 2 miles above the ground was minus-18 — a full 20 degrees warmer than the air at the surface. Had there been even light winds that night, some of that warmer air could have mixed to the surface and kept the temperature from getting as cold as it did.
06 February 2011
How to achieve record low temperatures
Everyone knows that you need an "Arctic cold front" to move through, but there are additional factors, as explained by Steven A. Acherman and Jonathan Martin at the
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