First, the wind fills the kite, giving it its shape, Then the wind blows over the kite. The kite, when unfolded, is shaped like a wing. That means that the air above the kite is flowing faster than the air below the kite. Faster air is thinner, exerting less air pressure. That means that there is more air pressure under the kite, pushing up, than there is over the kite, pushing down. So, the kite rises into the air, lifted by the pressure of the slow-moving air beneath it.