Avoiding Icing Conditions in Clouds

Source: www.pilotworkshop.com
Featuring Bob Nardiello

Mark:

"What about specific types of clouds Bob, and the types of icing you might find in different cloud formations?"

Bob:

"Well, in stratus clouds, which are layered clouds - we generally find rime icing. These types of clouds generally have icing layers no more than, perhaps, 3,000 feet thick. So a change in altitude of several thousand feet may take the aircraft out of the icing conditions.

Lake effect stratus clouds, for instance, south of the Great Lakes in the U.S., are exceptional in that they have very high moisture content. And the Great Lakes region, especially in the early winter when the northwest winds blow over unfrozen lakes, generally have icing conditions in the stratus clouds.

Cumulus clouds, on the other hand - they might be cumulonimbus or thunderstorm-type formations - generally result from vigorous convection. And they can have a very high moisture content. Cumulus clouds might be home to clear icing. However, they have limited horizontal dimensions, which means we can fly around them and avoid them.

Cirrus clouds are composed of ice crystals. And remember, cirrus clouds are very high clouds. Generally cirrus clouds do not result in structural icing. The reason for that is the moisture is already frozen in the form of ice crystals. And it doesn't deposit on the airframe as do super-cooled water droplets, which might exist in stratus or cumulus clouds."