4. these are three forms, rain (drops of water that fall from a cloud and have a diameter of at least 0.5 millimeter) and snow (precipitation in the form of ice crystals or, more often, aggregates of ice crystals). Other forms include sleet (falling small particles of ice that are clear to translucent), glaze (formed when supercooled http://wps.prenhall.com/esm_lutgens_atmosphere_10/0,6615,3175140-,00.html