This KS3 Geography quiz takes a look at the water cycle. Each year approximately 120,000km3 of water falls as precipitation on the land masses of the world and about 460,000km3 falls on the seas and oceans. Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain, snow and sleet are part of the water cycle. The water cycle is a way of describing how water is circulating on our planet.
All the world's ecosystems rely on water which mostly falls as rain. Water is constantly evaporating from the oceans, lakes, rivers, ponds and so on. This passes into the atmosphere and becomes part of the air. Warm air can hold more water vapour than cold air. When a mass of warm and cold air meet, the warm air rises above the cold air. This is called a front.
As it rises, the warm air cools and the water vapour condenses to form clouds. Clouds are made from tiny droplets of liquid water. If the warm air is carrying a lot of water vapour, the clouds are so dense that the droplets of liquid join together and fall as precipitation. Eventually, these end up back in a body of water and they can be evaporated again, continuing the cycle.