Atmosphere

What is the Atmosphere?

The atmosphere is a layer of gases surrounding Earth, held in place by gravity. It protects life by absorbing ultraviolet radiation, regulating temperature, and enabling weather patterns. The atmosphere is composed primarily of nitrogen (78%) and oxygen (21%), with trace amounts of other gases.

Layers of the Atmosphere

Troposphere

The lowest layer where all weather occurs and most commercial aircraft fly.

Altitude: 0-12 km

Temperature: Decreases with altitude

Features: Weather, clouds, most air mass

Stratosphere

Contains the ozone layer that protects Earth from harmful UV radiation.

Altitude: 12-50 km

Temperature: Increases with altitude

Features: Ozone layer, stable conditions

Mesosphere

The coldest layer where meteors burn up upon entering Earth's atmosphere.

Altitude: 50-85 km

Temperature: Decreases with altitude

Features: Meteor burning, coldest layer

Thermosphere

Very high temperatures due to solar radiation absorption; home to auroras.

Altitude: 85-600 km

Temperature: Increases with altitude

Features: Auroras, satellites, ISS orbit

Exosphere

The outermost layer that gradually fades into space.

Altitude: 600-10,000 km

Temperature: Extremely variable

Features: Transition to space, satellites

Weather Phenomena

Clouds

Visible masses of water droplets or ice crystals suspended in the atmosphere.

Formation: Water vapor condensation around particles when air cools to dew point

Precipitation

Water falling from clouds in various forms including rain, snow, sleet, and hail.

Formation: Water droplets or ice crystals grow large enough to overcome air resistance

Thunderstorms

Severe weather systems producing lightning, thunder, heavy rain, and sometimes hail.

Formation: Rapid upward movement of warm, moist air in unstable atmospheric conditions

Hurricanes/Typhoons

Massive rotating storm systems with strong winds and heavy rainfall.

Formation: Warm ocean water evaporation creating low pressure systems with rotation

Tornadoes

Violently rotating columns of air extending from thunderstorms to the ground.

Formation: Wind shear and instability in severe thunderstorm environments

Fog

Cloud formation at ground level reducing visibility.

Formation: Air cooling to dew point near the surface, causing water vapor condensation

Atmospheric Composition

78%

Nitrogen

N₂

21%

Oxygen

O₂

0.93%

Argon

0.07%

Other Gases

CO₂, etc.