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Clouds & icing conditions
Striker_03
Topic Author
Striker_03 created the topic: Clouds & icing conditions
Gday Bob,
In the BOM Manual of Met, they state in Altocumulus cloud you can expect light rime ice.
I was curious if the question was thick Altocumulus cloud, OAT -2deg and what type of icing, if any, can you expect..? Would it be safe to elect Clear ice and RIme ice as the most correct option based on the Met manual.
I think the clue here is the cloud type, not the temperature. Altocumulus are composed of very small droplets of supercooled water. The size of the droplets will dictate the type of ice rather than the temperature, so I would lean to the formation of rhime ice as most likely.
Clear ice is more likely with larger droplets than it is from the tiny droplets that are more typical of a layer of Ac. It is possible to get Ac that is 'towering', producing visible showers underneath that are more likely to form clear ice, but this would be the exception rather than the rule (and it would form in the showers rather than the cloud).
Richard replied the topic: Clouds & icing conditions
There is a bit of a dilemma here since the BoM manual doesn't mention clear ice as being a routine feature of Ac cloud. However the key word here (at least as far as CASA is concerned) is "thick". Thick means stronger updraughts which can support larger droplets. The temperature given in your question is really out of the range for rime ice so with thick Ac at -2 I'd go for clear ice.
What Ray has said is spot on but feedback from CASA would infer clear ice is to be expected. Now, whether the BoM agrees is another question
Cheers,
Rich
P.S. we'll look at changing that question to As rather than Ac so it conforms with the BoM manual. Errata to follow ...
