Answer:
The two greenhouse gases involved in downwelling infrared radiation are water vapor and carbon dioxide.
Step-by-step explanation:
Water vapor is the most abundant greenhouse gas in the Earth's atmosphere and plays a significant role in the greenhouse effect. It absorbs and emits infrared radiation, trapping heat in the atmosphere.
Carbon dioxide (CO2) is another important greenhouse gas that contributes to the greenhouse effect. While it is present in smaller concentrations compared to water vapor, it has a longer atmospheric lifetime and can remain in the atmosphere for many years. Carbon dioxide absorbs and re-emits infrared radiation, contributing to the warming of the Earth's surface.
It's important to note that while ozone and methane are also greenhouse gases, they are not directly involved in downwelling infrared radiation. Ozone primarily absorbs and scatters ultraviolet (UV) radiation in the stratosphere, while methane is a potent greenhouse gas that absorbs infrared radiation but is less abundant compared to water vapor and carbon dioxide.