[neilep (OP)]

Dear Polar Bears, Arctic Foxes and Snowologists.


Snow is my all time favourite cold white stuff that comes from clouds and makes things look nice:

Looky here, here's a nice scene.


 [ Invalid Attachment ]

Nice eh ?...(Actually, I'm in this piccy too but because I'm so sweet and innocently white, ewe just can't see me ...unless I fart !)


I've heard that in some cases it may just be too cold to actually snow !...is this true?..if so..why's that then ?..what's that all about ?


Let me snow will ya ?


A lick of your nose and a sheepy cuddle awaits ewe !




mwah mwah mwah mwah mwah



Neil
Snowwoman Humper
xxxxxxxxxxxxxxxxx

[DoctorBeaver]

It snows at the South Pole and it gets fekin cold there

[neilep (OP)]

Well this is what I understood too !..in all the coldest places there is indeed snow !....

I am sure I heard that this was and Earthbound fact too....

[LeeE]

I think it may be something to do with warmer air being able to hold more water vapour than cold air, so what you need for it to snow (or just rain) is relatively warm air with lots of moisture meeting cold air.  This lowers the temperature of the warm air and causes the moisture in it to condense and fall.  The layers of air that it falls through have an effect too - remember the dry rain thread, where the rain is heated and evaporates before it reaches the ground as a result of falling through a lower level region of hot dry air?

[dentstudent]

There are many areas in both the North and South Polar regions that are classified as deserts. There are regions in which it has not precipitated for many decades, if not centuries because the air is so cold, that it cannot retain moisture. Many of the apparent snowstorms are simply the snow that is being whipped up on the wind, and isn't being precipitated. Of course, there are areas where it does snow etc, but there are certainly also areas where it is too cold to snow.

"Antarctica is the world's largest desert" (Smithsonian Website)

[paul.fr]

Can It Be Just Too Cold To Snow ?

NO.

http://www.thenakedscientists.com/forum/index.php?topic=15448.0

[Pumblechook]

Wife says that. 

I think it is a feature of where Britain is in the World.  When the atmos pressure is high it is cold and dry.  When the pressure falls it is warmer and wet.

There get a lot more snow in Spain where a lot of interior is well above sea level.  It gets cold and it snows.   

[dentstudent]

Here is a good explanation (http://www.weatherimagery.com/blog/too-cold-to-snow/)

The answer to the question of can it be too cold to snow is no, it can’t be too cold to snow, but is gets increasingly difficult the colder it gets.

First, an important concept. Warm air can contain more water vapor than colder air. That is to say, there is more water vapor present for producing precipitation in warm air than in cold air. When any air mass reaches the point where it can’t contain any more vapor, it becomes saturated (also called the dew point). When the dew point is reached condensation occurs, clouds form, and the more droplets that form, the greater the chance of them colliding and forming bigger drops. When they get big enough, they fall to the ground as precipitation and if the air is cold enough, they fall as snow. But when the air is really cold, it can’t absorb as much water vapor and therefore has less precipitable content for making snow.

You can see from the chart below, that as the air gets colder there is less water vapor present. The less water vapor in the air, the less precipitation that can be produced. When it is 32°F (0°C) there is a lot more water vapor present than at 0°F (-18°C), so a lot of snow can be produced and the snowflakes are usually bigger. When the air gets really cold, there really isn’t enough water vapor in the air to get a whole lot of precipitable accumulations in a short amount of time and the snowflakes decrease in size. Therefore, as it gets colder it takes much longer for there snow to accumulate on the ground. And when it’s really cold, say below -40°F (-40°C) very little precipitation can be produced. Ice crystals can form, but they are extremely small.



There are a couple other reason why it’s hard for snow to form in really cold temperatures. One of them being, there is less evaporation taking place. For this reason, cold air is usually much drier than its dew point, unless you happen to live next to a large body of water that hasn’t frozen over. The drier the air, the colder it has to get to reach its dew point and ultimately before condensation will occur.

The other reason snow has a hard time forming in really cold temperatures is that the atmosphere is usually a lot more stable. It’s hard to get really cold air to rise and expand so that the little amount of water vapor will condense and form snow. There are exceptions (there always are!). One of them being a mountain which can force the air upwards causing expansive cooling at which point the air will achieve its dew point. Another being a warm air mass moving over top of a very cold airmass.

So putting this all together, snow can form at any temperature provided the right conditions exist, but it has an increasingly difficult time forming in really cold air because there is less water vapor present. Right around freezing is where you will see the most snow. This is because the air can contain the most moisture yet still be cold enough to freeze. Once it drops below -20°F, your chances of snow are virtually nil (but still possible). Ironically, when temperatures are less than -40°F, snow can form without ice nuclei. However, these ice crystals are extremely small and accumulations are virtually unnoticeable.

[mistyB]

Thanks for that answer!  I have had a few arguments about that in my day.  I always thought there was a window of temperature that it would be possible to snow in...good to know I was wrong, lol!

[Pumblechook]

Britain seems to have a climate such that in Winter as the atmos pres rises it gets cold.   It is the high atmos pres which is preventing snow.  We have been locked in to high pres for nearly 2 weeks maybe and there has been very little snow.  It is set to get warmer but wetter next week.   

[Karen W.]

Cool beans Paul and Stuart..I have always heard that and thought it true.. thanks for busting the myth!

[BenV]

Cool beans Paul and Stuart..I have always heard that and tought it true.. thanks for busting the myth!

Intentional pun?

[paul.fr]

Cool beans Paul and Stuart..I have always heard that and tought it true.. thanks for busting the myth!

Intentional pun?

Intentional pun! I don't even understand the beans, cool or not!

Note: Why does nobody ask "when is it too warm to snow?"