Earth's Atmosphere Layers and Composition Explained

Composition of the Atmosphere

• Nitrogen: 78%
• Oxygen: 21%
• Other: 1% (carbon dioxide, ozone)

Due to the pull of gravity, the atmosphere’s density decreases with altitude. Weather is directly related to air pressure, and the pressure of an air column on a body decreases as altitude increases.

Layers of the Atmosphere

Troposphere

Temperature: Decreases. This is the lowest, thinnest, and densest layer, containing 80% of the atmosphere's mass. Weather occurs here. The tropopause acts as a barrier between cold and hot air, and this is where airplanes fly.

Stratosphere

Temperature: Increases. Contains 19% of the air. Temperature rises because gas particles absorb solar radiation. It houses the ozone layer, which shields humans from ultraviolet radiation. Weather balloons operate here.

Mesosphere

Temperature: Decreases. This is the coldest point of the atmosphere. Friction causes asteroids to burn up, protecting Earth from potential meteorite impacts.

Thermosphere

Temperature: Increases. Temperature rises due to the absorption of solar radiation, though air pressure and density are very low. This layer absorbs solar radiation and creates auroras (Northern and Southern lights).

Exosphere

Temperature: Varies. This is the highest, outermost layer where air molecules are far apart with very few particles. Most satellites orbit in this region.