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Precipitation (Water Falling from the Sky)

There are many different types of precipitation —rain, snow, hail, and sleet for example—yet they all have a few things in common. They all come from clouds. They are all forms of water that fall from the sky. Additionally, they all affect life on Earth, causing some people to leap with glee while making others scowl, mumbling about umbrellas or snow shovels, causing garden flowers to grow or causing massive crop damage.

The most common types of precipitation:

Drops of liquid water fall from the clouds when water vapor condenses around dust particles in the clouds, forming tiny droplets that eventually get too big for the cloud to hold so they fall, growing larger as they collect more water on their way down.

Snow is ice that falls from the sky. Each snowflake is a delicately complex arrangement of ice crystals. A snowflake forms when water vapor sublimates, or turns directly from a gas into its solid form, ice.

Hail is ice that falls from the sky, often in round shapes. Hailstones form within thunderstorm clouds when upward moving air keeps pellets of frozen water from falling. The pellets grow larger as drops of very cold water hit them and freeze. Eventually the balls of ice become so large and heavy that they fall to the ground as hailstones. The largest documented hailstone weighted more than one and a half pounds! Scientists estimate that it reached a speed of more than 80 mph as it fell toward Earth.

Sleet is like slush falling from the sky. Sleet forms when raindrops freeze into ice as they fall to the ground. They are usually smaller and wetter than hailstones.