In which atmospheric layer does the ozone layer reside?

• A. Trophosphere
• B. Stratosphere
• C. Mesosphere
• D. Exosphere

Answer: (B)

The ozone layer resides in the stratosphere, which is the second layer of the Earth's atmosphere, situated above the troposphere and below the mesosphere. The stratosphere contains a high concentration of ozone (O3) molecules, which play a crucial role in absorbing the majority of the sun's harmful ultraviolet (UV) radiation. This absorption is vital for protecting living organisms on Earth, as excessive UV radiation can lead to skin cancer and other health issues.

In contrast, the troposphere is where weather events occur and is characterized by a decrease in temperature with altitude but does not contain the ozone layer. The mesosphere, located above the stratosphere, contains fewer ozone molecules and does not serve the same protective function. The exosphere is the outermost layer of the atmosphere, composed mostly of light gases and extending into outer space, where the concept of the ozone layer is not applicable. Thus, the correct identification of the stratosphere as the layer holding the ozone layer underlines its significance in shielding the planet from harmful solar radiation.