Lower Atmosphere

Basics

The lower atmosphere

What happens in the air surrounding us?

A thin layer of air surrounds our planet which becomes less and less dense the further we go from the Earth's surface. This layer is known as the atmosphere (atmos is the Greek word for gas or vapour, sphaira means sphere).

The composition and properties of air not only make it possible for plants and animals to live on Earth, they also control our climate.  If we look up into the sky on a clear day we see only blue sky.  However, there are distinct layers in the atmosphere which have different properties.  The lowest layer, where we live and where weather takes place, goes up to eight kilometers in altitude at the poles, and has as altitue of 15 kilometers in the tropics.  This layer of the atmosphere is known as the troposphere.  This word also has Greek roots, tropo means 'something changes'.

In the troposphere, it is the temperature which changes with altitude.  Temperature decreases with height up until the end of the troposphere, the region of the atmosphere known as the tropopause.  In this unit you will learn about the properties, composition, chemistry and processes in this layer.

The list below gives you an overview of what we cover in this 'basics' section.  For more detailed information, have a look in the 'read more' section.

1. An introduction to the troposphere

 - Variations with height and temperature
 - Different landscapes - the horizontal extension
 - What does tropospheric air consist of?
 * Worksheet 1: Air and temperature
 * Worksheet 2: Local climate

2. The greenhouse effect, light and the biosphere

 - Greenhouse effect and light
 - Greenhouse gases
 - What do plants emit?
 - Vegetation fires
 * Worksheet 1: Vegetation fires
 * Worksheet 2: The effect of themal radiation on greenhouse gases
 * Worksheet 3: The greenhouse as model of the troposphere

3. Ozone and nitrogen oxides

 - Ozone - what is it, what does it do?
 - Nitrogen oxides - what do they do and how are they formed
 - Ozone smog - how is it formed?
 * Worksheet 1: Effect of ozone
 * Worksheet 2: Ozone smog in the troposphere