Most ultraviolet radiation in sunlight is absorbed by which layer?

The stratosphere is the layer of Earth’s atmosphere that absorbs the majority of ultraviolet (UV) radiation from the sun. This is primarily due to the presence of ozone (O₃) in this layer, which effectively absorbs UV radiation, particularly the more harmful UV-B and UV-C types. By filtering out most of this harmful radiation, the stratosphere plays a critical role in protecting living organisms on Earth from potential DNA damage and other harmful effects associated with increased UV exposure.

In addition to the protective function, the absorption of UV radiation in the stratosphere leads to an increase in temperature within this layer, which is distinct from the cooler temperatures in the troposphere below. The interaction of UV radiation with ozone is essential not only for protecting biological life but also for regulating atmospheric temperatures and dynamics.

The troposphere, which is the lowest layer of the atmosphere where weather occurs, does not have the same concentration of ozone and thus does not absorb UV radiation to the same extent. Similarly, the mesosphere and the tropopause—the boundary between the troposphere and stratosphere—also do not have the ozone concentration necessary for significant absorption of UV radiation. Hence, the stratosphere is the correct answer as it is the primary