The Atmosphere ICS 3

California State Standards Earth Science 8a. Students know the thermal structure and chemical composition of the atmosphere

Composition of the Atmosphere 1% <1% <1% 21% 78%

Layers of the Atmosphere

Layers of the Atmosphere - Earth’s atmosphere is divided into 4 layers, according to the temperature gradient.

Altitude Temperature

Layers of the Atmosphere Troposphere - Weather occurs and life exists here The tropopause begins at approximately 10 meters above the surface of the earth and ends at about 20 meters. This is where the temperature does not change.

Layers of the Atmosphere Stratosphere - Similar composition to troposphere but without water. -The stratopause begins at about 45 and ends at approx. 53 meters. Contains ozone (O3) layer which absorbs harmful ultraviolet radiation from the sun

Layers of the Atmosphere Mesosphere - Air has very low density and is the coldest layer. - The Mesopause is more than 80 kilometers above the surface and temperatures approach -90 degrees Celcius .

Layers of the Atmosphere Thermosphere - Has very few air molecules which receive direct rays from the sun - Has a high temperature because it is heated by the Sun. The space shuttle orbits in the middle to upper part of this layer. The Aurora Borealis occurs in this layer.

California State Standards Earth Science 8c. Students know the location, role, and properties of the ozone layer

The Ozone Layer oxygen we breathe is diatomic (O2) ozone is a triatomic molecule (03)

The Ozone Layer Ozone forms in the stratosphere Ozone absorbs harmful ultraviolet radiation from the sun

The Ozone Layer (UV radiation) + 3O2  2O3

The Ozone Layer and Humans

catalyst: something that speeds up a chemical reaction The Ozone Layer and Humans certain chemicals humans put in the air act as catalysts in breaking up ozone molecules catalyst: something that speeds up a chemical reaction

The Ozone Layer these catalysts are called chlorofluorocarbons (CFC’s) and Humans these catalysts are called chlorofluorocarbons (CFC’s) a few CFC molecules can destroy hundreds of ozone molecules

California State Standards Earth Science 4c. Students understand the mechanism and significance of the greenhouse effect.

The Greenhouse Effect

The Greenhouse Effect greenhouse gases trap energy from the sun inside Earth’s atmosphere carbon dioxide (CO2) water vapor (H2O) methane (CH4) CFC’s and other pollutants

Greenhouse gasses

California State Standards Earth Science 8b. Students know how Earth’s atmosphere evolved over time

Evolution of the Atmosphere

Earth was formed by inelastic collisions Evolution of the Atmosphere Earth was formed by inelastic collisions volcanic eruptions (outgassing) and bombardment of material from comets and asteroids formed the early atmosphere

Evolution of the Atmosphere gg

Evolution of the Atmosphere Chemical reactions through time, in the presence of water, changed the methane (CH4) and ammonia (NH3) into nitrogen (N2), hydrogen (H2), and carbon dioxide (CO2)

Evolution of the Atmosphere Hydrogen (H2) escaped because it’s lightweight, leaving mostly nitrogen (N2).

Evolution of the Atmosphere photosynthetic bacteria evolved and converted carbon dioxide (CO2) into oxygen (O2)

Evolution of the Atmosphere levels of gases in the atmosphere have been stable for the past 600 million years