"Roy Smith" wrote in message
...
"O. Sami Saydjari" wrote:

This question is a question on physcial phenomena, NOT on regulation (so
I am starting a new thread).

As I understand it, icing happens between +2C and -10C.

There was just a posting from Mike Rapoport in which he said he's seen
icing as cold as -20C.

Icing is statistical in nature and contrary to pilot observations to the
contrary, is more a function of the size of the droplets, than some exacting
temperature range. FAA studied icing under a program tittled to reflect
"large droplet" icing, but the results of the study were the opposite of the
observed information. (large vs small droplets) You are in more danger of
an icing event where the size of the droplets is small and the airplane is
small.