Lower Atmosphere

Read more

Tropospheric processes

When we talk about chemical reactions most of us think about processes occurring in large industrial plants and in laboratories.  However, thousands of chemical reactions also occur every second in the air we breathe.  Most of these chemical reactions are oxidation processes or are started with the help of sunlight.

1. Chemical and physical processes occur everywhere in the air and in the clouds.   We can think about the atmosphere, both over the cities and the countryside, as a big chemical plant which continuously produces new molecules and destroys old ones.   Photomontage: Elmar Uherek.

In this unit we will learn about the most important oxidising compounds in the atmosphere - ozone and the hydroxyl and nitrate radicals.  We will look at the importance of sunlight and how energy is transported through the atmosphere.  We will also explain in more detail how greenhouse gases affect our climate.  Finally, we will discuss the special reactions of ozone in the troposphere and how human activity has altered the chemistry of the lower atmosphere.

Unit 1: Main oxidants and observation

 - Oxidation in the atmosphere
 - Night-time conditions and chemistry
 - Measurement techniques - Spectroscopy
 * Worksheet 1: Quiz on OH and NO3
 * Worksheet 2: The interrelation of light, absorption and colour

Unit 2: Radiation, greenhouse gases and the greenhouse effect

 - The Earth's radiation budget and the greenhouse effect
 - Carbon dioxide and methane
 - Water vapour feedback and clouds
 * Worksheet 1: Experiment with CO₂ and water
 * Worksheet 2: Model experiment for the greenhouse effect

Unit 3: Ozone and fire

 - Why is ozone dangerous?
 - Regulation of ozone abundance
 - Vegetation fires and their global importance
 * Worksheet 1: Ozone and its chemical properties
 * Worksheet 2: Model experiment on photochemical smog
 * Worksheet 3: Global fire maps

Unit 4: Gases in the atmosphere

 - Distribution of gases
 - Concentration of gases in the air