Which one of the following is the lower-most layer of the earth's atmosphere:

Correct option is D

Correct Answer: (D) Troposphere
Explanation:
→ The Troposphere is the lowest layer of the Earth’s atmosphere, extending from the Earth’s surface up to about 8–15 km (higher at the equator, lower at the poles).
→ It contains approximately 75–80% of the total mass of the atmosphere and almost all weather phenomena, such as clouds, rain, and storms.
→ Temperature in the troposphere decreases with altitude at an average rate of 6.5°C per km.
→ The boundary between the troposphere and the stratosphere is called the tropopause, which acts as a barrier preventing mixing between the two layers.
Information Booster:
→ Extends from the Earth’s surface up to 8–15 km.
→ Contains the highest concentration of air, water vapor, and weather systems.
→ Temperature decreases with height at 6.5°C per km.
→ Air pressure decreases rapidly with altitude in this layer.
→ Tropopause separates the troposphere and stratosphere.
→ Responsible for cloud formation, precipitation, and storms.
→ Supports life and human activities directly, as it contains breathable air.
Additional Information (Other Options):
Option (A) Mesosphere – Lies above the stratosphere; coldest layer where meteors burn.
Option (B) Stratosphere – Contains the ozone layer; temperature increases with height.
Option (C) Thermosphere – Uppermost layer with high temperatures; contains ionosphere; not the lowest.