The water cycle is how water moves from the sea to the air, the ground and back to the sea. The sun changes liquid water into vapour, this is called evaporation. As more water evaporates, clouds are made. Wind moves clouds along until the air cools and the water vapour is too heavy to carry. The cool water vapour begins to turn back to water droplets and fall as rain or snow. This is called precipitation. When rain falls onto mountains, lakes, rivers, the ground it will slowly make its way back to the sea where the cycle begins again.