Unit 3: We keep the air clean

The layer of gases that surrounds the Earth.

• weather

• ozone

• atmosphere

It contains the ozone layer.

• troposphere

• stratosphere

• outer layers

Atmospheric phenomena are the natural events that occur in this layer.

• troposphere

• stratosphere

• outer layers

There is almost no oxygen here.

• troposphere

• stratosphere

• outer layers

What causes air pollution?

• recycle

• use zero-emission transport

• industrial emissions

• save electricity

These are types of clouds.

• cirrus and cumulus

• rain, hail, snow

• thunder, lightning

• breeze, hurricane

The Sun heats the ocean. The water __________ and becomes water vapour.

• condenses

• evaporates

• falls

• collects

The water vapour rises and cools. It _________ to form tiny water droplets that form clouds.

• condenses

• evaporates

• falls

• collects

The water droplets join together. When they get heavy, they _________ to Earth as rain.

• condenses

• evaporates

• fall

• collects

The rain ________ in rivers, lakes and the sea. Water ends up in the ocean.

• condenses

• evaporates

• falls

• collects