Precipitation
Precipitation (pre-sip-uh-tay-shun) is any form of water that falls to the Earth's surface. Different forms of precipitation include rain, snow, sleet, and freezing rain.
Precipitation is important because it helps maintain the atmospheric balance. Without precipitation, all of the land on the planet would be desert. Precipitation helps farmers grow crops and provides a fresh water supply for us to drink.
Precipitation can also be damaging. Too much rain and snow can cause severe flooding and lots of traffic accidents. Hail can damage crops and cars. Freezing rain and sleet can destroy trees and power lines.
Types of precipitation
Rain
Raindrops form when millions of tiny
water droplets collide together in clouds to form larger ones. Eventually, they
become too heavy and fall out of the clouds as rain. Very small raindrops are
called drizzle . The place with the
greatest average yearly rainfall is on the island of Kauai in Hawaii.
Hail
Haildevelops in a cumulonimbus cloud as ice crystals are tossed around the
cloud. The tossing causes ice crystals to bump against each other and combine
into larger and larger pieces of ice. When these pieces become too heavy for the
cloud to handle, they fall as hail. Most hailstones are about the size of peas.
The largest one was the size of a melon and fell in 1970.
Snow
Snow falls when the air temperature is below freezing. Snow forms when water
freezes in a cloud and turns into snowflakes as they fall through the cloud. No
one has ever seen two identical snowflakes. The shape of snowflakes depends on
the temperature and height they were formed.
Sleet
Sleet forms when a partially melted snowflake or raindrop turns back
into ice as it is falling through the air. Sleet is usually tiny clear ice
pellets that bounce when they hit the ground.
Freezing Rain happens when raindrops fall in liquid form and
immediately freeze as they hit a cold surface.
Rainbows
Rainbows appear in the sky when there is bright
sunlight and rain. Sunlight is known as visible or white light and is actually a
mixture of colours. The sun's rays pass through millions of r aindrops. A
raindrop acts like a prism by bending and scattering the light to form one large
rainbow. You can only see a rainbow if the sun is behind you and the rain
in front. You can even make your own rainbow with a garden hose or water
sprinkler on a sunny day. The longest lasting rainbow was in North Wales, and it
lasted over 3 hours.
Answer the following:
1 Give a definition of precipitation.
2 Descibe how hail is formed.
3 How is a rainbow formed?