Rain is caused mainly from the change in temperature of moist air within a cloud. When the cloud gets cooler, the water vapor condenses into liquid water and falls to the Earth. The more water in the cloud the more susceptible it is to changes in temperature. There are four classes of rain: Convection rain (normal conditions), Frontal rain (usually happens on the coast), Relief rain (happens around mountains) and Monsoon rain (occurs within the Tropics due to the warming of ocean waters and the land). The rain is measured in increments of .2mm. “Light rain” or sprinkles means enough to see of feel, “Moderate rain” has a rate between 28 and 76 mm/hour and “Heavy” or “Torrential” rain is a term used for rain rates above 76 mm/hour.