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Clouds in the sky - What are clouds?

Clouds in the sky. What are clouds?

Clouds are made of water

What are clouds? Clouds are made of drops of water or ice. When the wind picks up water from the ocean or from the land on Earth, it can carry tiny drops of water up into the sky. These drops are too small for you to see.

More about wind
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What’s the atmosphere?

The air is cooler far above the earth, because of how the wind pushes the air around.

Why do clouds form?

Up in the sky, the tiny water drops cool down. Being cooler helps the drops to stick to other tiny particles in the air: dust, or sea salt, or ice. Little by little, the drops stick together to make larger drops. When they are as big as raindrops, gravity makes the raindrops fall to the ground as rain. If it’s cold enough, the raindrops freeze into crystals – that’s snow.

Why does it rain?
What is gravity?
More about snow

Why are some clouds white?

A white man wearing a suit made of blue sky and clouds fabric

Looking for a Halloween costume? You can go as a blue sky with clouds in this snappy suit! Click for more fun costumes!

If there’s a lot of water drops together, most of the sunlight that hits the cloud reflects off the water or ice. Then the light reaches your eyes, where it looks white.

What is sunlight?
How do eyes work?

Because clouds reflect sunlight, a layer of clouds in the daytime can reflect sunlight away from the earth and keep us cooler. At night, clouds can hold the heat in like a warm blanket. Clouds keep the sun’s heat from drifting away from Earth into space.

Why are some clouds gray or black?

In a thick cloud, the water drops scatter the light in all directions instead of reflecting it. Then not all of the light reaches your eyes, so the cloud can look gray or black.

Light and light waves

Fog is a cloud near the ground

Clouds can happen at any height above the ground, if the air is the right temperature. Sometimes clouds are actually touching the ground. We call that fog. If you go up to the top of a mountain or in an airplane, you will be above most of the clouds. After it rains, the clouds disappear, because the water they were made of has all come back down to Earth again.

The four kinds of clouds

On Earth, there are four main types of clouds:

Clouds on other planets

On other planets, there can be clouds made of other things than water.  Venus is covered by thick clouds, but the clouds there are made of drops of sulphuric acidchlorine, and fluorine, and would be poisonous to you. Jupiter has clouds made of ammonia. But Mars has clouds made of water, like our clouds.

What is chlorine?
More about the planets
All our space articles

So what are clouds?

What are clouds made of? Did you find out from this article? Let us know in the comments!

Looking for another source to cite? Check out this one from NASA!

Learn by doing: what kind of clouds are in the sky today near you?
More about rain

Bibliography and further reading about the atmosphere:


Learn by Doing – Clouds
More about clouds
More about Thunderstorms
And more about Weather home