Too Cold To Snow?

[IndieSinger]

I've always been taught that it obviously CAN be too cold to snow, because snow generally only falls when it's between -2 and +2. Below -2 (in the air) it falls as ice/hail and above +2 it melts and falls as rain. Lots of people argue with me, but never really have a valid point. One thing they often say is that it snows in Antarctica, and it's colder than -2 there, but we all know that the snow there is mostly just settled ice/snow being blown around by strong winds. So can anyone offer a valid reason why/when/how it CAN'T be too cold to snow?

[Mortartube]

The only example that I can think of is a temperature inversion, where the upper atmosphere is warmer than lower altitudes. It may me minus several degrees on the ground but at ideal snow precipitation temperatures in the cloud layers.

[manics_]

The temperature of the air affects the amount of water vapor it can hold. Colder air holds less water. To have a significant snow, you need significant water vapor in the air. At temperatures well below freezing there is not enough water in the air to get much snow.

[IndieSinger]

Great, thankyou Mortartube, I had that idea myself. Manics_ - aside from the interesting technical information, doesn't that prove my point?

[incitatus]

you are right and wrong indie. air temperature is imprtant, but not on the grouund. consider that most hail in the uk falls in july!. It is about cloud temperature. average ground temp in the steppes of russia in winter is about -20 and i assure you it snows there. lots. The point is whether there is a temp inversion as stated above. IN the uk the statement has some validity as you need a low pressure area for precipitation, and this tends to raise local temperatures.

[BadBob]

How many of the people who say it snows in antartic have been there. There's plenty of ice and its white but that doesnt mean its snowing. When they say this reply with "Is it snowing in your freezer" ?

[incitatus]

it does snow in anarctica, just not that much. coastal regions receive several metres a year but the internal regions only get a few centimetres. Check the british antarctic survey if you dont beleive me. I asssure you they have been there.

[incitatus]

for snow to form one must satisfy the following conditions: A temperature below 0 celsius pervading all the way from cloud to ground; a saturated vapour content of the air (normally consequent on a cloud temperature drop); nucleation sources (dust preferably). If all of these can be satisfied then snow will fall. Prolonged cold weather lowers the air moisture content, hence the antarctic desert phenomenon. BUT cold itself does not preclude snow.

[anthomson]

I remember being told at school that the expression comes from the fact that water turning too solid releases energy - hence it tends to feel milder as snow is about to fall. Conversely its feels cold when the snow melts (since it requires energy from the atmosphere to turn back in to a liquid ).