Another snow question

This I hear a lot, admitingly only in the UK. Can it be, "too cold to snow"?

:roll:

No, apparently. Watched James May's Man Lab with the husband last week, can't remember the science bit, but it can't be too cold to snow, so they say. They reminded viewers that it snows in the Arctic regions at minus-whatever...

I am pretty sure the reason behind the saying is as follows.

In the UK, when it gets very cold, it is usually because there is no cloud cover. Especially if you get a cloudless night in deepest winter. It is because of the lack of clouds that the saying "It is too cold to snow" came about.

That does not in any way mean the statement is correct, just a common held theory on why it is used.

The maximum snow conditions are when the temperature is just cold enough to form snow. Warm air holds more water vapour than colder air.

When the air temp gets really cold, water vapour content decreases, and there is less precipitation. Hence the snowflake sizes become smaller. So it may snow heavily at + 2 deg, but much less at - 2deg.

Hence, even at -5 to -7 deg C, the snow is in the form of tiny shards of ice. There is much less deposition.

Also, when the ambient temp is really low, there is less air rise from the ground, hence little movement of ground source water vapour. This condition further decreases snow deposition.

To answer the question, it can't be too cold to snow.It just depends on when you stop calling it snow.

Pray for cold weather, but not too cold!

On the other hand, generally the colder it is, the more snow you get for an equivalent precipitation coming down as rain. Wet snow might be a 5:1 ratio, 10:is average, 30:1 for extremely dry snow.

That explains it! On the GFS graphs it says rain in mm and snow in cm

So '5' is 5mm of rain or 5cm of snow :D

and just a few hundred feet of elevation can make the difference between precip that falls as rain or falls as snow.