Precipitation

By Sam Belanger

What is it?

• Precipitation is water in solid or liquid form, that falls from the air to the Earth’s surface

• There are four main types: Snow, Rain, Sleet, and Hail

• Precipitation reaches the Earth’s surface, when the water vapor droplets in clouds become so heavy they actually fall to the Earth’s surface

Rain

• The most common form of precipitation• Consists of liquid water that falls from the

clouds to the Earth’s surface• Before a drop of rain falls, it must increase in

size about 100 times its normal diameter• The droplet actually starts out smaller than a

period you would put at the end of a sentence

Snow

• Snow is the most common form of solid precipitation

• Forms when temperatures are so cold that water vapor changes directly to a solid

• Can fall as individual ice crystals, or combine to form snowflakes

• The size of a snowflake depends on how many ice crystals join together

Sleet

• Also known as freezing rain• Forms when rain falls through a layer of

freezing air• The rain freezes, which produces falling ice• Sometimes does not freeze until contact with

the ground, and changes into a layer of ice called glaze

Hail

• Solid precipitation that falls as balls or lumps of ice• Usually forms in cumulonimbus clouds, updrafts then carry

raindrops to high altitudes in the cloud where they freeze• Another updraft can send the hail up to the cloud, forming

another layer of ice on the droplet• If an updraft is strong enough, the droplet can continue to

receive many layers of ice• If it gets heavy enough, it will fall to earth and can become

very dangerous• Largest recorded-17.5 inches long, 1.67 lbs

Measurement

• If you are curious about the amount of rainfall you’ve received, you can use an instrument called a rain gauge to measure the amount of rainfall

• A rain gauge consists of a funnel and cylinder, and measures the exact amount of rainfall

• Snow is simply measured using a yardstick, and measured by depth and water content

Value

• Precipitation has a great impact on Earth• It replenishes water that the Earth needs• Without it, the whole world would simply be

an enormous desert• Precipitation also helps farmers grow their

crops, and provides a fresh water supply for us to drink

Precipitation Fun Facts

• Nevada is the driest state with an average of 9.5 inches of precipitation each year.

• Hawaii is the wettest state with an annual average of 63.7 inches

• Mt. Baker, Washington received 1,140 inches of snowfall in the 1998-99 season

• Buffalo, New York received 39 inches of snowfall in a 24 hour period, costing 5 million dollars for snow removal

Resources

• http://www.fondriest.com/science_library-htm/precipitation.htm

• My Science Book• http://www.theweatherprediction.com/precip

types/

• http://allaboutweather.org• http://blogs.eveningsun.com• http://www.infoplease.com/images