What first comes to your mind when you hear about the greenhouse effect? How would you picture the Earth if there were no greenhouse gases present in the atmosphere?

You have learned that certain gases can absorb radiation and transfer the energy absorbed from this radiation to surrounding molecules through collisional de-excitation. This causes the kinetic energy of surrounding molecules to increase, resulting in increased temperature. In this topic we will focus on the effect that these gases have on climate.

Open the Earth's Radiation Balance learning tool and click on the bottom, right hand panel entitled “The Greenhouse Effect”.

Take care to work through the visualization and thoroughly understand the answers to each of these questions:

1. How is thermal energy ‘trapped’ in our atmosphere?
2. What types of gases act as greenhouse gases?
3. Why do some atmospheric substances act as greenhouse gases while others do not?