In article ,
Brendan DJ Murphy writes:
I've always wanted to know how much precipitation (in rain mm) is
required to produce 1 foot of snow.

I've heard statements such as "1 foot of snow is equivalent to 1 inch
of rain" (ie: 12:1 ratio)
Ive also heard "1mm of rain is equivalent to 1cm of snow" (ie: 10:1
ratio)
Which one is correct?
snip

The answer is both/neither. The "drier" the snow, the more air it
contains and so the lower the water content. Dry snow will have the 10:1
or 12:1 ratio you quote. Really wet snow, close to turning to sleet/rain
can have a ratio as low as 4:1.
--
John Hall
"It is a very sad thing that nowadays there is so little useless
information."
Oscar Wilde (1854-1900)