Eddie Kansas City, Missouri Thanks for your question. As you are probably aware, the three main gases that contribute to the greenhouse effect are water vapor, carbon dioxide, and ozone.
Water vapor is the most important greenhouse gas.
It has the largest impact on increasing the near-surface air temperature. The concentration of water vapor is highly variable - even at the surface. We experience this variability at the surface directly as changes in relative humidity. The relative humidity depends on both the air temperature and the amount of water vapor in the air. Whether the concentration of water is high or low at the surface, however, the concentration of water vapor drops rapidly with increasing height.