Final answer:
Greenhouse gases are gases that absorb and emit radiant energy within the thermal infrared range, causing the greenhouse effect. The four major greenhouse gases are carbon dioxide (CO2), methane (CH4), water vapor, and nitrous oxide (N2O).
Step-by-step explanation:
Greenhouse gases are gases that absorb and emit radiant energy within the thermal infrared range, causing the greenhouse effect. The four major greenhouse gases are carbon dioxide (CO2), methane (CH4), water vapor, and nitrous oxide (N2O). These gases trap heat in the atmosphere, similar to how the glass panels of a greenhouse keep heat from escaping.