Mystery #2Tier 2weather / air
Why does the wind blow?
You can't see it, but wind shoves clouds across the sky, bends trees and fills sails. Air is invisible and seems to come from nowhere. So what actually sets all that air moving?
Your guess
What's your hunch about what makes still air start moving as wind?
There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.
Make a guess to unlock the hints and the answer.