How Do Clouds Form? | A2 ESL Science Reading Passage

Use this A2-B1 ESL science reading passage to learn how clouds form. It includes key vocabulary, reading comprehension questions, and answers for English learners.

Clouds form when warm, moist air rises and cools.

Reading Level

A2-B1

Word Count

228 words

Reading Passage

Clouds look soft and light, but they are made of water. A cloud is a group of many tiny water drops or tiny ice crystals floating in the sky.

Clouds often begin with the sun. The sun warms water in oceans, lakes, rivers, and soil. Some of this water changes into water vapor. Water vapor is invisible, so we cannot see it in the air.

Warm air can hold more water vapor than cold air. When warm, moist air rises, it moves higher into the sky. The air higher up is usually cooler.

As the air cools, it cannot hold as much water vapor. The water vapor begins to change back into tiny drops of liquid water. This change is called condensation.

Tiny drops need very small pieces of dust, salt, or smoke to form around. These pieces are called particles. Many tiny drops gather together around particles. When there are enough drops, we can see a cloud.

Some clouds are made mostly of water drops. Very high clouds may be made of ice crystals because the air is very cold.

Clouds can tell us something about the weather. Thin white clouds may mean fair weather. Dark, thick clouds may bring rain or snow.

Clouds form because water moves through the air. The sun warms water, vapor rises, air cools, and tiny drops join together in the sky.

The sun warms water, water vapor rises, air cools, and clouds form.

Key Vocabulary

Word	Meaning	Example
cloud	many tiny water drops or ice crystals in the sky	A white cloud moved across the sky.
water vapor	water in the form of gas	Water vapor rises into the air.
condensation	the change from gas into liquid	Condensation helps clouds form.
particle	a very small piece of something	Water drops can form around a particle.
crystal	a small solid with a clear shape	Ice crystals can make high clouds.

Reading Comprehension Questions

1. What are clouds made of?
2. What does the sun warm on Earth?
3. Why does warm, moist air rise?
4. What happens when water vapor cools?
5. What can dark, thick clouds bring?

Answers

1. Clouds are made of tiny water drops or tiny ice crystals.
2. The sun warms water in oceans, lakes, rivers, and soil.
3. Warm air rises and carries water vapor higher into the sky.
4. It changes back into tiny drops of liquid water.
5. Dark, thick clouds may bring rain or snow.

Short Summary

Clouds form when warm, moist air rises and cools. Water vapor changes into tiny drops or ice crystals that gather in the sky.

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