The character of the snow surface after a snowfall depends on the original form of the crystals and on the weather conditions present when the snow fell. Credit: Rich Herrmann/Flickr Snow on the ground The sun emerges after heavy snow hit Mount Vernon, Iowa. As weather conditions change, the snowpack can change as well, and this affects the characteristics of the snow. Snow is an accumulation of packed ice crystals, and the condition of the snowpack determines a variety of qualities, such as color, temperature, and water equivalent. As a result, this extremely cold region receives little snow. The Dry Valleys are quite cold but have very low humidity, and strong winds help wick any remaining moisture from the air. Antarctica's Dry Valleys, for instance, form the largest ice-free portion of the continent. It is true, however, that most heavy snowfalls occur when there is relatively warm air near the ground-typically -9☌ (15☏) or warmer-since warmer air can hold more water vapor.īecause snow formation requires moisture, very cold but very dry areas may rarely receive snow. Snow can occur even at incredibly low temperatures, as long as there is some source of moisture and some way to lift or cool the air. While it can be too warm to snow, it cannot be too cold to snow. As a general rule, though, snow will not form if the ground temperature is at least 5☌ (41☏). In this case, snowflakes will begin to melt as they reach this higher temperature layer the melting creates evaporative cooling, which cools the air immediately around the snowflake. However, the snow can still reach the ground when the ground temperature is above freezing if the conditions are just right.

If the ground temperature is at or below freezing, the snow will reach the ground. Snow forms when the atmospheric temperature is at or below freezing (0☌ or 32☏). Snowstorms also rely heavily on temperature, but not necessarily the temperature we feel on the ground. Exchange for Observations and Local Knowledge of the Arctic (ELOKA)įor snow to fall, moisture must be present in the atmosphere.NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC).

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