[LAUGH] The Coriolis force [LAUGH] That’s such a naughty question. Right. Ok. [LAUGHS] The Coriolis effect. It’s a difficult thing to understand i think To the left -oh is it to the right? Oh I always get it wrong. Umm.. Ask that to Brian Hoskins. If you’re on a roundabout in the park and threw a ball at you. Straight at you. It will appear to the person on the roundabout, if you’d like, that the ball follows a curved path. In fact, the ball is traveling straight. Coriolis force is linked to the spinning of the Earth. When you’re on a rotating system and you start to move there’s all sorts of different things happening and you tend to be flung off at right– right angles to the way you want to go. And that’s what the Coriolis force is always saying “okay you want to go in that direction? I want you to go that direction.” Here we’ve got an old satellite dish which we painted black. And umm– if i put a ball bearing on this, just as expected, it rolls towards the middle. Gravity pulls it down towards the middle there. Next, professor Erskine spins the dish to simulate the rotation of the Earth. To witness the effect of this rotation on a traveling object. He has set up a revolving camera above the dish. The ball bearing represents the air, moving across the Earth’s surface Clearly, the ball is traveling backwards and forwards. But the revolving camera shows that it is going in circles as well. You see it from here, it’s all this rotating with the dish. Then when we look on over there, what you see relative, on the camera, it’s rotating with it. It’s going round, in– almost in circles, snaking on itself. This simple experiment demonstrates that air is spun around by the Earth’s rotation.