Can it really be too cold to snow

A.� This is a common expression that, although theoretically incorrect, is in practice true.

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Q.� Why theoretically incorrect

A.� Because it isn't temperature alone that determines whether snow falls. Another important factor is the amount of available moisture. As long as all the contributory factors are right then it can never be too cold to snow.

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Q.� But in practice it can be too cold to snow

A.� Yes, because of the effect that temperature has on moisture. The colder it gets the less moisture the atmosphere can hold.

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Q.� What are all the contributory factors for snowfall

A.� Snowfall is dependent on a number of factors, not just temperature alone. Contributory factors include altitude, moisture and temperature.

At what low temperature is snow unlikely

Once it gets below a very chilly -20 Celsius snowfall becomes unlikely.

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Fortunately these temperatures are usually only experienced in extreme environments such as Siberia and Antarctica.

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Q.� So where did all the snow come from in Antarctica

A.� Yes, given that 70% of the world's fresh water is locked up in the Antarctic icecap, its provenance is puzzling. One theory is that the ice cap is the result of millions of year's worth of snow blown from, warmer, coastal areas.

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Want to know more about Antarctica's climate Click here.

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Q.� At what temperature does most snow fall

A.� A temperature of around -10 Celsius near the ground seems to be favourable for heavy snowfalls.

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Want to know why snowflakes are always symmetrical

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Heard an expression that doesn't appear to make sense and want The AnswerBank to explain

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by Lisa Cardy