Earth’s Atmosphere 5/20/14

Composition 78% Nitrogen (N2) 21% Oxygen (O2) Released when living things decay and volcanoes erupt 21% Oxygen (O2) Produced by plants and some protists during photosynthesis 1% Various Atmospheric Gases Water vapor Carbon Dioxide Solid particles such as dirt, dust, and ash are carried in air

Atmospheric Pressure Atmosphere is held in place by Earth’s gravity Gravity pulls on gas molecules Air pressure Stronger near surface Weaker the further away Altitude Air Pressure

Atmospheric Temperature Air temperature changes as you increase altitude Sections of warmer and colder temperatures Temperature changes based on how solar energy is absorbed Type of gases affect solar absorption

Layers of Atmosphere Divided into four layers based on temperature Troposphere Stratosphere Mesosphere Thermosphere “-sphere”  each layer surrounds the Earth like a hollow ball

Troposphere Lowest layer of the atmosphere Densest of the four layers We live here Densest of the four layers 90% of atmosphere’s total mass Layer in which weather occurs Extends to 6-7 miles (~33,000 ft) above Earth’s surface

Stratosphere Located above the troposphere Air is very thin and contains little moisture Few clouds exist here Contains the Ozone Layer (O3) Protects from UV rays Ranges from 7-31 miles above the Earth’s surface

Mesosphere Located above the stratosphere Coldest layer of the atmosphere As low as -90oC (-130oF) Difficult to study layer Weather balloons and aircraft cannot reach layer Extends from 31-53 miles above Earth’s surface Mesospheric Clouds

International Space Station Thermosphere Uppermost atmospheric layer Warmest layer of the atmosphere As high as 1,700oC (3,100oF) Influenced by solar radiation Contains the Ionosphere and Aurora borealis Electrically charged particles Extends from 56-311 (or 621) miles above Earth’s surface International Space Station