Weather and the Atmosphere

What is the atmosphere?

Look up. The air all around you reaches high, high into the sky. This blanket of air around Earth is called the atmosphere.

You cannot see air, but you can feel it. When the wind blows your hair, that is air moving. When you blow up a balloon, you fill it with air. The atmosphere keeps us warm and gives us the oxygen we need to breathe.

All of our weather happens in the lowest part of the atmosphere, close to the ground.

What is weather?

Weather is what the sky and air are doing right now. Weather can be:

• Sunny — the Sun shines and it feels warm.
• Cloudy — grey clouds cover the Sun.
• Rainy — water falls from the clouds.
• Windy — the air pushes and rushes around you.
• Snowy — frozen water falls as soft, white flakes.

Weather can change in one day. The morning can be sunny and the afternoon can be rainy!

How do clouds form?

Clouds start with water you cannot see. Warm air picks up tiny bits of water from oceans, lakes and puddles. This is called water vapour.

When that warm, wet air rises, it cools down high in the sky. The water vapour turns back into tiny droplets. Millions of droplets float together — and that is a cloud! When the droplets grow big and heavy, they fall as rain. You can learn more in our lesson on the water cycle.

What makes the wind blow?

Wind is moving air. But why does air move?

The Sun heats some parts of Earth more than others. Warm air is light and rises up. Cooler air rushes in to take its place. That rushing air is wind! On a windy day, you can fly a kite or watch leaves dance across the ground.

Hot or cold? Measuring the weather

People who study weather use special tools:

• A thermometer measures temperature.
• A rain gauge measures how much rain falls.
• A wind vane shows which way the wind blows.

When you know the temperature, you know whether to wear a coat or a t-shirt.

Try it yourself: be a cloud watcher

You do not need any tools to watch the weather!

1. Each morning for one week, go outside or look out of a window.
2. Draw the sky. Are there clouds? Are they white and fluffy, or grey and flat?
3. Write down whether it is sunny, cloudy, rainy or windy.
4. At the end of the week, look back. Did the weather change a lot, or stay the same?

You have just made your own weather diary — exactly like real weather scientists do!

To see how weather changes over the whole year, read about climate and weather next.