THE ATMOSPHERE & ITS LAYERS

PRERNA FOR IAS

THE ATMOSPHERE & ITS LAYERS

1. Atmosphere

The atmosphere is the gaseous envelope surrounding the Earth. It acts as a protective blanket that supports life by providing oxygen, regulating temperature, and shielding the planet from harmful solar radiation. The atmosphere is composed mainly of nitrogen, oxygen, argon, carbon dioxide, and water vapour. It extends hundreds of kilometers above the Earth's surface and is divided into several layers based on temperature variations. The atmosphere plays a crucial role in weather formation, climate regulation, and the water cycle. Without the atmosphere, Earth would experience extreme temperatures and life as we know it could not exist.

2. Temperature and Pressure in the Atmosphere

Atmospheric temperature and pressure change with altitude. As altitude increases, air becomes less dense and atmospheric pressure decreases because there are fewer air molecules above. Temperature does not decrease uniformly; instead, it follows a zigzag pattern through different atmospheric layers. In the troposphere, temperature decreases with height, while in the stratosphere it increases due to ozone absorption of ultraviolet radiation. In the mesosphere, temperature decreases again, and in the thermosphere it rises sharply. These variations influence weather patterns, aircraft movement, atmospheric circulation, and the distribution of gases. Understanding these changes is important in meteorology and climatology.

3. Five Layers of the Atmosphere

Scientists divide the atmosphere into five main layers based on temperature changes: Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. Each layer has distinct characteristics and functions. The troposphere contains most weather phenomena and atmospheric mass. The stratosphere houses the ozone layer, which absorbs harmful ultraviolet radiation. The mesosphere burns up most meteoroids entering Earth’s atmosphere. The thermosphere contains ionized particles and supports radio communication and auroras. The exosphere is the outermost layer where atmospheric gases gradually merge into outer space. Together, these layers protect Earth and create conditions suitable for life.

4. Troposphere (0–12 km)