Rain
Drops of water that fall from clouds caused by condensation of the atmosphere.
http://dictionary.kids.net.au/word/rain
http://www.weatherwizkids.com/weather-rain.htm
http://www.kidsgeo.com/geography-for-kids/0115-rain.php
http://en.wikipedia.org/wiki/Rain
http://science.howstuffworks.com/nature/climate-weather/atmospheric/question479.htm