Hey flip - I'll would check next time I'm in moscow but my micrometer is at the menders.
I don't think freezing fog is such an issue - as you say the drops are not large enough to fall under their own weight and won't lead to severe icing. Isn't it something to do with the droplets have to be a certain size to release enough latent heat to produce clear ice rather than rime ice when it strikes the airframe?...or something like that
is life still orange for you?