Dear Tom,
Can it be too cold to snow? I am having a discussion with a friend about this. I so no; she says yes.
James Morris, Belvidere
Dear James,
You win the bet. As long as there is some moisture in the air (and there is always some) it can never be too cold to snow. For snow to occur, airborne moisture must condense into ice crystals as the air is chilled to below its condensation temperature. It snows once these ice crystals grow large enough to fall. But since very cold air can hold only minuscule amounts of moisture, it can be safely said that heavy snows do not occur at very low temperatures. However, snow has been reported at manned stations in Antarctica at temperatures near -70 degrees. And here in Chicago an inch of snow fell on Sunday evening, Jan. 10, 1982, with the temperature at -15 degrees.