Water from oceans, rivers, ponds and lakes evaporates all the time. Water evaporates even in winter, when the temperatures are low. In summer, huge quantities of water evaporates from the oceans. Plants also lose water in the form of water vapour through the process of transpiration. The water vapour that is formed mixes with the air. The warm summer air being lighter, carries the water vapour upwards. The higher the air goes, the cooler it becomes. After reaching a certain height, the air becomes very cold and the water vapour in the air condenses into extremely small water droplets. These droplets together form clouds. As the clouds rise higher, more vapour condenses and collects on the tiny water droplets. The water droplets grow bigger, become heavy and ultimately fall down as rain. If the temperature close to the land is 0 ° C (freezing point) or less, the water droplets in the clouds turn into ice crystals. This gives rise to snowfall. Rain and snowfall are forms of precipitation. The water in the oceans, rivers, lakes and ponds evaporates all the time. It is a continuous process. Continuous evaporation, condensation and precipitation of water on the Earth in a cyclic manner is called water cycle.