The greenhouse effect of greenhouse gases is due to their ability to absorb infrared (a kind of thermal radiation). The ability of greenhouse gases to absorb infrared rays is determined by their molecular structure. There are non-polar covalent bonds and polar covalent bonds in the molecule. Molecules are also divided into polar molecules and non-polar molecules. The strength of the molecular polarity can be expressed by the dipole moment μ. Only vibrations with changing dipole moments can cause observable infrared absorption spectra. Molecules with dipole moments are infrared active; while molecular vibrations with Δμ=0 cannot produce infrared vibration absorption, they are non-infrared active. [1] In other words, greenhouse gases are infrared active molecules with dipole moments, so they have the ability to absorb infrared and preserve infrared heat.
The main greenhouse gas in the atmosphere is water vapor (H2O). The greenhouse effect produced by water vapor accounts for about 60%-70% of the overall greenhouse effect, followed by carbon dioxide (CO₂), which accounts for about 26%, and the other is ozone ( O₃), methane (CH₄), nitrous oxide (N₂O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), chlorofluorocarbons (HCFCs) and sulfur hexafluoride (SF6), etc.