Correct Option
The correct option is It contains the Ionosphere..
Explanation
The Earth's atmosphere is divided into five concentric layers based on temperature profiles: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. The Thermosphere is the fourth layer, situated directly above the Mesosphere.
Option-wise Analysis
- It is located below the Mesosphere. is Incorrect: The Thermosphere is located above the Mesosphere. The Mesosphere extends up to an altitude of approximately 80 km, while the Thermosphere extends from 80 km to roughly 400 km.
- It contains the Ionosphere. is Correct: The Thermosphere contains the Ionosphere. The Ionosphere is a region containing electrically charged particles (ions) created by solar radiation. This layer plays a vital role in radio communication by reflecting radio waves back to Earth.
- Temperature decreases with height. is Incorrect: In the Thermosphere, temperature increases rapidly with increasing height. This rise in temperature is caused by the absorption of extremely high-energy solar radiation, such as X-rays and ultraviolet rays. Temperatures can reach up to 2,000°C or higher.
- It is the lowest layer. is Incorrect: The Troposphere is the lowest layer of the atmosphere, where weather phenomena occur. The Thermosphere is the second-highest layer, located beneath the outermost Exosphere.
Key Takeaway: The Thermosphere is characterized by a rapid increase in temperature with altitude and contains the Ionosphere, which is essential for long-distance radio communication.