A cloud is a mass of tiny water droplets or ice crystals that float in the air.
Clouds look fluffy and light, but the truth is the amount of water that makes up one cloud can weigh more than an airplane! The are many types of clouds. The three main types of clouds are Cumulus, Stratus, and cirrus clouds.

How do clouds form?
Clouds are formed from water. The water on earth heats up from the sun’s rays. The heat changed the water into a gas called water vapor. High in the sky above the earth, the air is cold. When the water vapor rises, the cold air cools the water vapor. As the water vapor cools, it changes into tiny water droplets. the droplets stick to tiny pieces of dust floating through the air.
Billions of those tiny droplets together form clouds.
Cumulus Clouds

White fluffy clouds that look like cotton are called cumulus clouds. The word cumulus means a pile or heap.
Cumulus clouds are usually less than 6,500 feet above the earth.
Heavy rain and snow come from cumulus clouds. Cumulus clouds higher in the sky signify fair, calm weather. Cumulus clouds close to the ground and grey indicate that rain or snow is coming.
Stratus Clouds

Clouds that are spread out across the sky are called Stratus clouds. Stratus clouds look like a blanket that is lying across the sky. They can be white or gray.
Stratus clouds that are high in the sky are called altostratus clouds.
Stratus clouds usually mean chilly weather or overcast. Precipitation from stratus clouds is light and falls as a drizzle or a snow flurry.
Cirrus Clouds

Cirrus clouds resemble white smoke and signify calm, clear weather. The word cirrus means a curl or ringlet in someone’s hair.
Cirrus clouds are high in the sky. They are over 20,000 feet above the earth.
The shape of a cirrus cloud shows which way the wind is blowing high up in the earth’s atmosphere.
It is cold where cirrus clouds form; they are only made up of ice crystals.
When cirrus clouds bunch together with other cirrus clouds and turn gray, they form cirrostratus clouds. It means it will rain or snow within 24 hours.
There will be no rain or snow when you see white cirrus clouds.
Cloud Height
Clouds can be categorized by height. Adding prefixes or suffixes to types of clouds tells how high they are in the atmosphere. Prefixes are words we add in front of other words, and suffixes are words we add to the end of other words.
The prefix cirro is used for high clouds. Clouds that are 20,000ft high. Cirrocumulus are high clouds.

The prefix nimbo or the suffix nimbus is used for low clouds. Clouds that are 6,500 ft above earth. Nimbstratus clouds are clouds you see when there is heavy precipitation for long periods, such as heavy rain or snow that lasts a couple of hours. Cumulonimbus clouds are thunderstorm clouds.

The prefix alto is used for mid-level clouds. Clouds that are between 6,500 and ft-20,000 ft. Altocumulus clouds are small patches of clouds.
Do clouds make rain?
Precipitation falls from the clouds. Precipitation is a liquid, either frozen or water that forms in the earth’s atmosphere and falls down to the earth. Rain, sleet, and snow are all precipitation and fall from clouds.
How?
In each cloud, tiny water droplets join together with other water droplets already in the clouds.
When those droplets get too heavy, they fall from the sky as rain. Rain occurs in the spring, summer, fall, and sometimes winter.
If the air is cold, the water droplets freeze and become ice crystals. When a bunch of ice crystals sticks together, they form a snowflake.
The frozen droplets fall as snow. Snow usually occurs in winter.
How do clouds get their color?
Clouds often look white; why? Clouds look white because they reflect light from the sun.
The sun’s light is made up of all the colors in the rainbow. When all the colors mix together, they give off what’s called white light. White light is the color you see when you look at clouds.
So why do clouds sometimes look gray?
When billions of water droplets form, the clouds get very thick.
When the clouds are thick, the sun’s light cannot shine through, so the clouds look gray. Soon the droplets in the clouds will get so big that the cloud can no longer hold them and fall from the cloud as rain.
That’s why we know when clouds are gray; it will rain soon.
Fog
Did you know that fog is a type of cloud? Fog is a cloud that is close to the ground. It is a stratus cloud.
Fog forms when moist air close to the ground is cool.

How fast do clouds move?
Clouds are always moving across the sky, but how do they move, and how fast do they move?
Clouds move across the sky by the wind. The speed at which they moved is based on a couple of things, the type of cloud it is, how high the cloud is in the sky, how fast the wind is blowing, and in what direction the wind is blowing. On average, clouds move between 30-120mph.
Clouds that are lower to the ground move slower than clouds high up in the atmosphere.
Tornadoes
Are tornadoes clouds? Tornadoes are violent rotating columns of air. They touch both the earth’s surface and cumulonimbus clouds. Though tornadoes are not clouds alone, they are formed by clouds.
Most wild weather, like tornadoes, hurricanes, and blizzards, involve clouds.
Water Vapor Experiment
Above, it says that clouds are formed from water vapor. The water comes from the Earth’s oceans, ponds, lakes, puddles, etc… Take a plastic cup and fill it with water.
Use a marker to mark the water level. Place the cup in a window that gets lots of suns. Each day watch the cup and mark the water line.
Watch what happens to the water. You will notice that the water level will get lower and lower.
Why? Because the sun turns the water into water vapor and floats up into the sky.
Looking for more fun experiments to do with clouds? Learn how to make your own clouds with this fun cloud-making science experiment. This science experiment is fun and easy for kindergarten students and other young elementary school students. Check it out today.