Rainfall refers to the amount of rain that an area receives over a period of time. Rainfall is necessary to provide water supply but too little or too much can cause droughts or floods respectively. Rainfall is measured using a rain gauge, which collects rainwater in a container and the amount is measured in millimeters or centimeters. Rain forms through the processes of evaporation, condensation, and precipitation, where sun heats and evaporates water which rises and cools to form clouds and water droplets that fall as rain.
