Precipitation is water that falls from the atmosphere to Earth’s surface in either liquid or solid form. Rain, snow, hail, and sleet are the four major types of precipitation. All forms of precipitation originate from clouds.
Types of Precipitation
1. Rain
Rainfall occurs when water vapor in the air condenses into liquid droplets that grow large enough to fall to the ground.
(Also read: Types of Rainfall | Convectional, Orographic, and Cyclonic)
2. Snow
Snowfall occurs when the temperature in the atmosphere is below freezing and water vapor turns directly into ice crystals. These ice crystals stick together in clouds to form snowflakes. When the snowflakes become heavy enough, they fall to the ground due to gravity.
Snowfall with large snowflakes usually occurs when the temperature is slightly above freezing and the air is moist. In contrast, powdery snow forms in colder, drier conditions.
3. Hail
Hailstones form within strong thunderstorm clouds. For hail to develop, the storm cloud must have significant vertical height, and its upper portion must be at a temperature below freezing.
When water droplets in the lower portion of the cloud are pushed up by the updraft winds, they freeze to form hailstones. These hailstones grow larger as more supercooled water droplets collide with them and freeze. Eventually, when the hailstones become too heavy for the updrafts to support, they fall to the ground.
4. Sleet
Sleet occurs when snowflakes partially melt as they pass through a layer of warm air, then refreeze into ice pellets before reaching the ground. For sleet to form, there must be a cold layer of air (below freezing) near the surface, with a warmer layer of air above it that melts the falling snow. As the melted snow passes through the cold layer, it refreezes into small ice pellets. Sleet occurs only under specific weather conditions where these temperature layers are present.
