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Precipitation
Some clouds bring rain or snow. Water in any form
that falls to Earth from clouds is called
precipitation
.
Precipitation is measured using a rain gauge. The kind of
precipitation that falls depends on how cold the air is.
Precipitation falls as rain when the air between the
clouds and Earth’s surface is warmer than 0 degrees
Celsius (°C). Most precipitation falls as rain.
Sleet forms when rain passes through air that is cooler
than 0°C. Because the temperature is below 0°C, the
raindrops freeze, forming bits of ice.
Hail forms in thunderstorm clouds especially when
there are strong winds blowing large droplets of water
upward. To form hail, a large part of the cloud has to be
below 0°C.
Snow falls from clouds made of tiny ice crystals. If the
air between the clouds and Earth is cooler than 0°C, the
ice crystals do not melt as they fall.
A rain gauge
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