Question

Which layer of the Earth's atmosphere contains the ozone layer?

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Hint:

Remember the order of atmospheric layers from the Earth's surface upward: \textbf{Troposphere $\rightarrow$ Stratosphere $\rightarrow$ Mesosphere $\rightarrow$ Thermosphere $\rightarrow$ Exosphere} A useful trick: \textbf{“TSMTE”}. The \textbf{Ozone Layer lies in the Stratosphere}, which is the second layer of the atmosphere.

Answer 1

The Correct Option is B

Concept: The Earth's atmosphere is divided into several layers based on temperature variation with altitude. Each layer has distinct characteristics and plays a different role in protecting and sustaining life on Earth. The main layers of the atmosphere are:

• Troposphere: The lowest layer of the atmosphere where weather phenomena such as clouds, rain, and storms occur. It extends from the Earth's surface up to about 8–18 km depending on latitude.
• Stratosphere: Located above the troposphere and extending roughly from 18 km to about 50 km above the Earth's surface. This layer contains the ozone layer, which absorbs most of the Sun's harmful ultraviolet (UV) radiation.
• Mesosphere: Extends from about 50 km to 85 km above the Earth. It is the layer where most meteors burn up due to friction with atmospheric particles.
• Thermosphere: Located above the mesosphere, extending from about 85 km to several hundred kilometers. This layer contains ionized gases and is where phenomena like auroras occur.

The ozone layer is a region with a high concentration of ozone (\(O_3\)) molecules. These molecules absorb harmful ultraviolet radiation from the Sun, particularly UV-B and UV-C rays. Without this protective layer, most life on Earth would be severely affected due to increased exposure to harmful radiation.
Step 1: Understanding where ozone concentration is highest.
The ozone layer is primarily concentrated between approximately \(15\) km and \(35\) km above the Earth's surface. This altitude range lies within the stratosphere.
Step 2: Eliminating the incorrect options.

• Troposphere: Contains weather systems but does not contain the ozone layer. Small amounts of ozone may exist here but not as a protective layer.
• Mesosphere: Too high above the Earth; ozone concentration is negligible.
• Thermosphere: Extremely thin air with ionized particles; ozone does not accumulate here.

Step 3: Identifying the correct atmospheric layer.
Since the ozone layer exists in the region between \(15\)–\(35\) km altitude and this region lies within the stratosphere, the correct answer is: \[ \text{Stratosphere} \]