THURSDAY FEBRUARY 22 - IS IT EVER TOO COLD OR TOO WARM TO SNOW?


Some of the most consistently cold places on earth - for example, Antarctica or Greenland - are covered with thousands of feet of ice, giving the impression that it snows a lot there. Actually, these places are better described as "cold deserts." They get very little snow. It's just that what falls, doesn't melt.

But it's never too cold to snow. Snow can fall at incredibly low temperatures as long as there's some source of moisture and some way to lift or cool the air. However, it is tough to get a really heavy snowfall at very low temperatures because you can't build up much moisture in really cold air.

Of course, there is a limit on how warm it can be to get snow. Think about it this way. Even in summer, raindrops may have started high in the clouds as snowflakes. The flakes simply melted on the way down as they passed through warmer air. It usually takes at least 1000 feet of above-freezing air to melt snowflakes. But if the layer of warmer air is thinner than that, the flakes can survive all the way down, even if the air temperature right near the ground is in the low 40s. That's about the upper limit for how warm it can be to still get snow.

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