WEATHER!

You cannot see the wind, but you see what it does — it rustles trees, whips up waves, cools you when you are sweaty, and can knock over bins when it is strong. In science words: wind is the horizontal movement of air (vertical "wind" is more often called an updraught in storms). Topic 5 taught that air presses down. Here we learn: when pressure is not the same in two places, the atmosphere tries to even things out — and that push — along with the planet spinning and drag at the ground — is why air flows as wind.