8.6 The Atmosphere

8.6.2 Describe the structure of the troposphere and lower stratosphere.

The atmosphere is divided into layers based on temperature.  Two of those are:

• the Troposphere, and
• the Stratosphere.

Troposphere

The troposphere is the lowest layer of the atmosphere.

This is the layer where we live and where weather happens.

It contains about 75% of the total mass of the atmosphere.

Temperature in this layer generally decreases with height.

The height of the troposphere varies with location, being

• higher over warmer areas and
• lower over colder areas.

The boundary between the stratosphere and the troposphere is called the tropopause.

Stratosphere

In this layer the temperature increases with height.

This is because the stratosphere houses the ozone layer.

The ozone layer is warm because it absorbs ultraviolet (UV) rays from the sun. 

8.6.4 Outline the characteristics of the troposphere in terms of:

(a) horizontal and vertical motions;

Vertical motions of air are common in the troposphere and can be very large.

The name troposphere was coined from the Greek for 'turning sphere' because of the vertical overturning circulations that mix up the air in this layer.