Childrens Illustrated Encyclopedia

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Color

Rivers

Storms

Water

Weather

Wind

SnoW and hail

in cold weather the water in

a cloud freezes and forms ice

crystals. These crystals stick

together and fall as snowflakes.

The snow may melt slightly as it

falls, producing sleet. in some

clouds strong air currents can toss

frozen raindrops up and down. Each time

they rise and fall, the frozen drops collect

more ice crystals and water, and frozen

layers build up like the skin around an onion.

Eventually they become so heavy that they fall

to the ground as hailstones.

ThE WaTER ThaT fallS from the sky as rain or snow is taking part

in a continuous cycle. it begins when the water on Earth’s surface

evaporates, or dries out, and enters the air as invisible water vapor. Rising

air carries the vapor into the sky. The air cools as it rises, and the water

vapor turns into tiny water droplets. These droplets are so small that they

float in the air, and a cloud forms. a rain cloud contains millions of water

droplets that merge together to form larger drops. When these drops

become too large and heavy to float, they fall to the

ground as rain and the cycle starts all over again.

if the air is very cold, the water in the cloud freezes

and forms snowflakes or hailstones. however,

rainfall and snowfall are not equally

distributed all over the world. deserts

have hardly any rain; tropical regions

can have so much rain that

there are severe floods,

while in the polar

regions snow falls

instead of rain.

Rain and snow

iCE CRySTal

a microscope reveals that

snowflakes are made of

tiny six-sided ice crystals.

no two crystals are

exactly the same.

Water seeps

underground

through a layer

of porous, or

permeable, rock

and flows down

to the sea.

Water droplets fall from a cloud especially

over high ground where the air is cooler.

The general name for rain, snow, sleet,

hail, mist, and dew, is precipitation.

lifE-giving Rain

Rain is vital to life on Earth. Plants

need water to grow, providing food

for us and other animals. Rain also

fills the rivers and lakes that

provide our water supply.

WaTER CyClE

Water enters the air from lakes,

rivers, seas, and oceans through

the process of evaporation. in

addition, plants, animals, and people

give out water vapor into the

atmosphere. The vapor stays

in the air for an average time

of 10 days and then falls as

rain or snow. it joins

the sea, rivers, and

underground water

courses, and the cycle

begins once more.

Trees and other

plants release water

vapor into the air

from their leaves.

Wind and the sun’s

heat cause water to

evaporate from the

oceans and other

large areas of water.

Water joins

rivers and streams and

flows down to the sea.

Cloud begins to form

from water vapor

in the atmosphere.

Rainbow

if the sun shines on a shower of rain,

you may see a rainbow if you are

looking toward the rain and the

sun is behind you. The raindrops

in the shower reflect the sun’s

light back to you. as the sunlight

passes through the raindrops,

it splits up into a circular band

of colors. you see the top part

of this circle as a rainbow.

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