If you look at the bottom left area of the image you can see that there are are air molecules. As the sun goes over the earth it heats ground, the air molecules then bump into the earth and they heat up. And as you know heat rises. so it goes up and hits the bottom layer of the atmosphere called the tropopause and moves over the water. Then it cools and sinks and the cicle starts again. But when the air moves towards the land it causes wind!!!