It's also very confusing as a dane, we often use 'sky' as 'cloud'. Very confusing :)
Unicorns and airborne? Technically a Pegasus should take over this responsibility.
Sky originally meant "cloud" in Old Norse but when the people in England began to adopt this word the meaning shifted to "sky". I think it makes a lot of sense if taking the weather of England in to account. Not entirely my idea though, original idea is from this youtube comment: https://www.youtube.com/watch?v=CDAU3TpunwM