Mike Rapoport wrote:
"O. Sami Saydjari" wrote in message
...

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. Assuming this
is correct, I have three questions.



MOST icing occurs between 0C and -10C but icing has been shown to occur
at -40C. Icing in cumulus clouds virtually always extends below -10C.and
often to below -20C



(a) Does that mean one is relatively safe if the surface temperature is
below -10C (and there is no temperature inversion, meaning that the
temperature is known to decrease as one goes up in altitude)?



Ice is less likely to be a problem than if it was 0C at the surface but,
again, icing can occur at temperatures much lower than -10C particularly in
clouds with vertical movement (cumulus).
.

(b) Is icing from 0C to +2C a possibility only when your aircraft skin
is colder than 0C (probably because you are descending from altitude)?
Or is there some other condition where this is possible?


This was the conventional thiinking buy a recent NASA study was unable to
document ANY ice formation above 0C.


However, keep in mind that most thermometers have some error in them.
So, even though ice doesn't form above 0C, it may form above 0C as
indicated on your airplane thermometer.


Matt