What are clouds?

Clouds come in all shapes and colours. Some clouds are white and fluffy like cotton wool. Others are dark and heavy.

Clouds are made up of tiny droplets of water.

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How do clouds form?

Clouds form when water on Earth heats up from the Sun and turns into a gas (water vapour). The gas rises up into the sky where it cools down and turns back into water droplets.

As more and more vapour rises and cools, it forms a cloud. When the droplets get too heavy they fall from the sky as rain.

If the air in the sky is very cold, the water droplets can turn into ice crystals. When a bunch of ice crystals stick together they form a snowflake.


Cloud levels

If you’ve ever been in an aeroplane and looked out the window, you may have noticed that some clouds look really high up while others seem very low. Different clouds sit at different levels.

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High-level clouds are too high and thin to produce rain or snow. The weather is much colder the higher you get, so these clouds are mostly made of ice crystals.

Middle-level clouds can be made up of water droplets or ice crystals. They occasionally produce rain or snow but it usually evaporates before reaching the ground.

Low-level clouds are normally seen close to the ground. They are made up mostly of water droplets and occasionally produce very light rain, drizzle, or snow.

Vertical clouds can form near the ground or high up in the sky. They often create rain and snow. 


Did you know?

  • Sometimes, clouds look colourful during a sunrise or sunset. This is because of dust particles in the air that have stuck to the water droplets.
  • Clouds that form on the ground are called fog.
  • The water that makes up a cloud comes from the ocean, rivers, lakes, ponds, streams and other sources.