Question: Each of the molecules in the IR Windows learning tool (H2O, CO2 and N2O) has several regions of infrared (IR) absorbance. For each molecule, which region of IR absorbance (in wavenumbers) will have the greatest impact on atmospheric temperatures?
To find the answer to this question, turn on 'Earth's Emission Curve'. A greenhouse gas has the most impact when its absorption peaks overlap strongly with the wavenumbers of energy emitted by the Earth. Look at the IR spectrum of each of the substances mentioned above and see if they have absorption peaks in the region of the IR spectrum where Earth emits IR radiation.
Carbon dioxide has a substantial absorption peak, in the region of Earth's IR emission, between 625 and 715 cm-1. Water absorbs energy radiated from the Earth between 1400 and 1800 cm-1. Nitrous oxide has two peaks of absorption in the region of Earth emission: 1315 to 1240 cm-1, and 600 cm-1.