Clouds and Rain

Clouds are not just decoration in the sky — they are made of millions of tiny water droplets and can tell us a lot about what weather is coming. Scientists have given different clouds their own names.

How clouds form

• The sun heats water in oceans, rivers, and lakes. Some water evaporates — it turns into an invisible gas called water vapor and rises into the air.
• High up where the air is cool, water vapor turns back into tiny droplets that gather to make a cloud. When droplets join and grow heavy, gravity pulls them down as rain.
• Example: You can see the same thing when warm shower steam hits a cool mirror and makes tiny drops.

Cumulus clouds — puffy and bright

• Cumulus clouds look like big, fluffy cotton balls stacked up in a blue sky.
• They form on sunny days with warm rising air. They usually mean fair, pleasant weather.
• Very dark, tall cumulus clouds can bring thunderstorms.

Stratus clouds — flat and layered

• Stratus clouds spread out in flat, gray sheets that cover the whole sky like a blanket.
• They often bring drizzle or light rain and make the day look dull and overcast.

Cirrus clouds — thin and wispy

• Cirrus clouds are very high up and look like thin white streaks or curly wisps.
• They are made of tiny ice crystals — not water drops — because it is so cold up there.
• Cirrus clouds often mean a change in weather is on the way.