Most rain begins as frozen water, at high altitudes. Then
the snow or sleet melts on the way down into warmer air. In
your dry desert air, you get virga, which is falling water
evaporating in the lower, dry air.

The amount of water available for precipitation can be
judged by the density [darkness] of the cloud. But it can
snow from clear air, as water vapor sublimates directly to
crystal form.

http://www.airweb.faa.gov/Regulatory...A?OpenDocument

This link is to AC 00-6, in several PDF files, it has many
answers.



wrote in message
ups.com...
| Tauno Voipio wrote:
| joe wrote:
| You Can't tell by looking at the clouds......come on
|
| Another vote for that - I'd also like to know whether
the substance just now coming is water or
| snow (and it's perfectly normal at this time of the year
here in the far North, Helsinki, Finland,
| 60 deg N).
|
|
| Think I'll give him Neil's answer because it looks nice
and logical
| too. I remember similar Qs at school regarding impending
heavy rainfall
| and answering, "Dark, low clouds". I wondered if snow
meant clouds
| being pure white, which apparently is not!
|
| And what do u mean you can't tell whether what's falling
is rain or
| snow?
|
| Ramapriya
|