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 Stratosphere Above the troposphere km above the surface As altitude increases, temperature increases Airplane level Ozone (O 3 ) 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