Hi all, a quick question regarding icing:
You are cruising in thick altostratus cloud where the outside air temperature is -2°C. What type of icing is most likely to occur?
A.rime ice
B.clear ice
C.both rime and clear

I saw this question from previous post. I would go for C, because the word ”thick ” means strong vertical development which can form large droplet. But someone says the answer A）rime ice only is correct.
Can’t find a solid answer. Can anyone help?

Clear ice would be correct. If that is one of my questions, can you let me know where you found it.

Bob

Hi Bob,
Thanks for your reply! This question isn't from your book, maybe it's a feedback from CASA or practice exam.

In the booklet from BOM, it says "light to moderate rime ice , clear ice possible in lower level " . So why don't we go for both rime and clear ice?

Sorry Bob, I find where it's from. It's on page311, reversion questions set 1 No.9. The answer you give is clear ice only. But some guys say rime and clear should be better.

It’s B clear ice for two reasons. 1st is the cloud type. As you mention the “thick” vertical development and thus larger water droplets. 2nd is the temp is only -2deg. So not as cold for when the large droplets impact the aircraft.
Combination of these two factors lead to a large, not so cold 0 to -10deg, droplet hitting the leading edge and then sliding back and freezing. Thus causing clear ice. Rime is formed at much colder temps -10-20deg and smaller droplets in stratiform clouds because they freeze on impact. Causing clumps of ice with air trapped inside as well. Hope this helps.