Robert M. Gary wrote:
"Mike Rapoport" wrote in message link.net...

Ice is "known" to be present anytime there is visible moisture in the liquid
state and the temp is below freezing. There will ALWAYS be icing under
these conditions. Always, no exceptions.



I"m not sure at what point you consider clouds to be liquid versus gas
(vapor). I've often flown in the clouds at -5C without picking up any
ice. I've also flown in the same looking clouds and did pick up ice. I
still believe that there is a lot yet to learn about predicting ice.
It seems like you are many times more likely to pick up ice in
cumulous clouds than stratus (from practical experience). It also
seems like stratus usually only make ice near the top. Richard Collins
has often written on the continuing research the gov't is doing trying
to better predict when ice will occur.

Yes, pretty hard to size water "droplets" when they are submillimeter to
micron sizes. That's why I advocate allowing the pilot the latitude to
take a look and make the call in real-time. Same as judging visibility
on an ILS. It is what it is when you are there, not what someone on the
ground things it is.


Matt