The Atmosphere

Miss Napolitano & Mrs. Rodriguez

Environmental Science

The Atmosphere

Atmosphere: mixture of gases that surround a planet

Includes nitrogen, oxygen, carbon dioxide, & other gases

Gases can be added/removed by volcanic gases, automobiles, & living organisms

Ex: photosynthesis, cell respiration

The Atmosphere

The atmosphere insulates Earth’s surface

Slows the rate at which the Earth’ surface loses heat

Keeps a stable temperature

Composition of the Atmosphere

Nitrogen: 78%

Enters the atmosphere during volcanic eruptions & when plants/animals decay

Oxygen: 21%

Mostly produced by plants

Other gases: argon, carbon dioxide, methane, water vapor

Atmosphere contains many types of tiny, solid particles called atmospheric dust

Air Pressure

Atmosphere is denser near the Earth’s surface

Due to gravity

Makes breathing difficult at higher altitudes

Layers of the Atmosphere

Layers divided based on temperature changes

The Troposphere

The Stratosphere

The Mesosphere

The Thermosphere

The Troposphere

Lowest layer of the atmosphere

As altitude increases, temperature decreases

Where weather conditions exist

Densest atmospheric layer

Extends 18 km above the surface

The StratosphereAbove the troposphere

10-50 km above the surface

As altitude increases, temperature increases

Airplane level

Ozone (O3) absorbs sun’s ultraviolet (UV) energy, warming the air & reducing UV to reach Earth

UV can damage living cells

The Mesosphere

Above the stratosphere

Extends to an altitude of ~80 km

Coldest layer

The Thermosphere

Farthest from the Earth’s surface

Nitrogen & Oxygen absorb solar radiation

Temperatures >2,000°C

Air is so thin that particles barely collide

Little heat is transferred

Would not feel hot to us

The Thermosphere (cont’d)

X-rays & gamma rays absorbed by nitrogen & oxygen causes electrically charged atoms (ions)

Ions radiate energy as light

Causes auroras (Northern & Southern Lights) near the poles

The Greenhouse Effect

Greenhouse Effect: warming of the Earth’s surface & lower atmosphere that occurs when gases absorb & reradiate infrared radiation

Makes temperature warm enough for life

Greenhouse Gases

Greenhouse gases: gases in the atmosphere that trap & radiate heat

Most abundant: water vapor, carbon dioxide, methane, & nitrous oxide

None exist in high concentrations

Quantities of greenhouse gases vary because of natural & industrial processes