Importance of the Atmosphere• Earths atmosphere is a thin layer of airthat forms a protective covering aroundthe planet.• Earths atmosphere maintains a balancebetween the amount of heat absorbed fromthe Sun and the amount of heat that escapesback into space.• It also protects life-forms from some of theSuns harmful rays.1Earth’s Atmosphere
Makeup of the Atmosphere• Earths atmosphere is a mixture of gases,solids, and liquids that surrounds the planet.• It extends from Earths surface to outer space.1Earth’s Atmosphere
Makeup of the Atmosphere• Earths early atmosphere, produced byerupting volcanoes, contained nitrogen andcarbon dioxide, but little oxygen.1Earth’s Atmosphere• Then, more than 2billion years ago,Earths early organismsreleased oxygen intothe atmosphere as theymade food with the aidof sunlight.
Makeup of the Atmosphere• Eventually, a layer rich in ozone (O3) thatprotects Earth from the Suns harmful raysformed in the upper atmosphere.• This protective layer eventually allowedgreen plants to flourish all over Earth,releasing even more oxygen.1Earth’s Atmosphere
Gases in the Atmosphere• This circle graph shows the percentages ofthe gases, excluding water vapor, that makeup Earths atmosphere.1Earth’s Atmosphere
Gases in the Atmosphere• The composition of theatmosphere is changing insmall but important ways.For example, car exhaustemits gases into the air.1Earth’s Atmosphere• Humans burn fuel for energy.• Increasing energy usemay increase the amountof carbon dioxide in theatmosphere.
Solids and Liquids inEarths Atmosphere• In addition to gases, Earths atmospherecontains small, solid particles such as dust,salt, and pollen.1Earth’s Atmosphere• The atmosphere also contains small liquiddroplets other than water droplets in clouds.
Solids and Liquids inEarths Atmosphere• The atmosphere constantly moves theseliquid droplets and solids from one regionto another.1Earth’s Atmosphere• For example, theatmosphere above youmay contain liquiddroplets and solids froman erupting volcanothousands of kilometersfrom your home.
Layers of the Atmosphere• Earth’satmospherehas layers.1Earth’s Atmosphere• There are fivelayers in Earth’satmosphere, eachwith its ownproperties.
Layers of the Atmosphere• The lower layers include the troposphereand stratosphere.1Earth’s Atmosphere• The upper atmospheric layers are themesosphere, thermosphere, and exosphere.• The troposphere and stratosphere containmost of the air.
Lower Layers of the Atmosphere• You study, eat, sleep,and play in thetroposphere, which isthe lowest of Earth’satmospheric layers.1Earth’s Atmosphere• It contains 99percent of the watervapor and 75percent of theatmospheric gases.
Lower Layers of the Atmosphere• The stratosphere, the layer directly abovethe troposphere, extends from 10 km aboveEarths surface to about 50 km.1Earth’s Atmosphere• A portion of the stratosphere contains higherlevels of a gas called ozone.• Each molecule of ozone is made up of threeoxygen atoms bonded together.
Upper Layers of the Atmosphere• The mesosphere extends from the top of thestratosphere to about 85 km above Earth.1Earth’s Atmosphere• The thermosphere is named for its hightemperatures.• This is the thickest atmospheric layer andis found between 85 km and 500 kmabove Earth.
• The ionosphereallows radio wavesto travel across thecountry to anothercity.• Within the mesosphere and thermosphere is alayer of electrically charged particles calledthe ionosphere (I AH nuh sfihr).Upper Layers of the Atmosphere1Earth’s Atmosphere
Upper Layers of the Atmosphere• During the day, energy from the Sun interactswith the particles in the ionosphere, causingthem to absorb AM radio frequencies.1Earth’s Atmosphere• At night, without solarenergy, AM radiotransmissions reflect offthe ionosphere, allowingradio transmissions tobe received at greaterdistances.
Upper Layers of the Atmosphere• The space shuttle orbits Earth in the exosphere.1Earth’s Atmosphere• The exosphere has so few molecules that thewings of the shuttle are useless.• In the exosphere, thespacecraft relies onbursts from smallrocket thrusters tomove around.• Beyond the exosphereis outer space.
The Ozone Layerabove your head,lies an atmosphericlayer called theozone layer.• Within the stratosphere, about 19 km to 48 km1Earth’s Atmosphere• Ozone is made ofoxygen.• Although you cannotsee the ozone layer,your life depends on it.
The Ozone Layer• An ozone molecule is made up ofthree oxygen atoms bound together.1Earth’s Atmosphere• The ozone layer contains a highconcentration of ozone and shieldsyou from the Suns harmful energy.
The Ozone Layer• Ozone absorbs most of the ultravioletradiation that enters the atmosphere.1Earth’s Atmosphere• Ultraviolet radiation is one of the manytypes of energy that come to Earth fromthe Sun.
CFCs• Evidence exists that some air pollutants aredestroying the ozone layer.1Earth’s Atmosphere• Blame has fallen on chlorofluorocarbons(CFCs), chemical compounds used in somerefrigerators, air conditioners, and aerosolsprays, and in the production of some foampackaging.
CFCs• Chlorofluorocarbon molecules destroy ozone.1Earth’s Atmosphere• When a chlorine atom from achlorofluorocarbon molecule comes near amolecule of ozone, the ozone molecule breaksapart.• One of the oxygenatoms combines withthe chlorine atom, andthe rest form a regular,two-atom molecule.
CFCs• These compounds dont absorb ultravioletradiation the way ozone can.1Earth’s Atmosphere• In addition, the original chlorine atom cancontinue to break apart thousands ofozone molecules.• The result is that more ultraviolet radiationreaches Earths surface.
The Water Cycle• Hydrosphere is a term that describes all thewater on Earth’s surface.2Energy Transfer in the Atmosphere• The constant cycling of water between theatmosphere and the hydrosphere plays animportant role indeterminingweather patternsand climate types.
The Water Cycle2Energy Transfer in the Atmosphere
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