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Earth’s atmosphere Earth’s atmosphere is a layer of gases surrounding theplanet. The Earth is surrounded by a blanketof air, which we call the atmosphere.It reaches over 560 kilometers fromthe surface of the Earth.Atmosphere: Absorbs the energy from the Sun, Recycles water and other chemicals, protects us from high-energy radiation and the frigidvacuum of space. The atmosphere protects and supports life.
Earth’s atmosphere Earth’s atmosphere is made of a mixture of gasescalled air. Nitrogen gas makes up about 78% ofEarth’s atmosphere. The second most abundant gas isoxygen, which makes up 21% ofEarth’s atmosphere. The third Argon (Ar, 0.9%). Carbon Dioxide (CO2, 0.03%).
Composition of the AtmosphereThe atmosphere is comprised of a variety of gases: Major Constituents (99%): Nitrogen (N): 78% Oxygen (O2): 21% Trace Constituents: Argon (Ar), about 0.9% Water vapor (H2O), up to 10000 ppmv Carbon dioxide (CO2), 350 ppmv Ozone (O3), near zero at the surface, up to 10 ppmv in thestratosphere Methane (CH4), 1.7 ppmv and others…..ppmv = “parts per million by volume”
Nitrogen is important toprotein which is found inthe body tissues of allliving things. Nitrogen is cycledthrough the soil and intoplants and finally whenliving things die anddecay.Nitrogen Cycle
Pressure in the atmosphere Atmospheric pressure isthe force per unit areaexerted into a surface by theweight of air above thatsurface in the atmosphereof Earth. The gas molecules closest toEarth’s surface are packedtogether very closely. This means pressure islower the higher up you gointo the atmosphere.
Pressure in the atmosphere At sea level, the weight of thecolumn of air above a person isabout 9,800 Newtons (2,200pounds)! This is equal to the weight of asmall car.
Pressure changes with altitudePressure varies smoothlyfrom the Earths surface to thetop of the mesosphere.
Measuring Pressure A barometer is an instrumentthat measures atmosphericpressure. Long ago, mercury barometerswere used Since mercury is a poisonousliquid, aneroid barometers areused today.
Layers of AtmosphereThe atmosphere has four layersThermosphereMesosphereStratosphereTroposphere
Layers of AtmosphereTroposphere Lowest and thinnest layer 16 km at equator, 8 km at poles 90% of the atmosphere’s mass Temperature decreases with altitude 6°C per kilometer Top of troposphere averages –50°C Where weather occurs Boundary between the troposphere, and the stratosphere iscalled the tropopauseView of troposphere layer from anairplanes window.
Layers of AtmosphereStratosphere Extends from 10 km to 50 km above the ground Less dense (less water vapor) Temperature increases with altitude Almost no weather occurrence Contains high level of ozone Ozone layer Upper boundary is calledstratopause.
Layers of AtmosphereMesosphere Extends to almost 80 km high Gases are less dense. Temperature decreases as altitude increases. Gases in this layer absorb very little UV radiation.
Layers of AtmosphereThermosphere Above the mesosphere and extendsto almost 600 km high Temperature increases withaltitude Readily absorbs solar radiation Temperature can go as high as 1,500°C Reflects radio waves
Layers of theAtmosphereThe four layers of theatmosphere include:1. the troposphere, wherewe live;2. the stratosphere, whichcontains the ozone layer;3. the mesosphere, wheremeteors burn; and4. the thermosphere, wheresatellites orbit Earth.
Layers of the Atmosphere The exosphere begins atabout 500 kilometers aboveEarth and does not have aspecific outer limit. Satellites orbit Earth in theexosphere.
The exosphere and ionosphere Communication on Earthdepends on satellites. Satellites transmitinformation used fortelevision shows, radiobroadcasts, data andphotos used in weatherreports, and long distancetelephone calls.
The ozone layer In the 1970s, scientistsnoticed that the ozonelayer in the stratosphereabove Antarctica wasthinning.
Chlorofluorocarbons & the ozone layer A group of chemicals calledchlorofluorocarbons (or CFCs)were once commonly used inair conditioners, in aerosolspray cans, and for cleaningmachine parts. In the London Agreement of1991, more than 90 countriesbanned the production anduse of CFCs except for limitedmedical uses.
The ozone layer absorbs the Sun’s high-energy ultraviolet(UV) radiation and protects the Earth. In the stratosphere, the CFCs break down and releasechlorine. The chlorine reacts with ozone molecules, which normallyblock incoming ultraviolet radiation.Chlorofluorocarbons & the ozone layer
Acid rain occurs when oxidesof sulfur and oxides of nitrogenare emitted into theatmosphere, undergo chemicaltransformations and are absorbedby water droplets in clouds.
Effects of Acid RainAcidification of bodies of waterDamage of vegetationDamage to building materials, statues, etc.
GREENHOUSE EFFECTThe trapping of heat by gases in the atmosphere. Naturally occurring greenhouse gases: Water vapor Carbon dioxide Methane Nitrous oxide Ozone Greenhouse gases that are not naturally occurring Hydro fluorocarbons (HFCs) Per fluorocarbons (PFCs) Sulfur hexafluoride (SF6)Generated in a variety ofindustrial processes.
The Greenhouse Effect on Earth The ground is heated by visibleand (some) infrared light fromthe Sun. The heated surface emitsinfrared light. The majority of Earth’satmosphere (N2 and O2) are notgood greenhouse gas. The small amount ofgreenhouse gases (H2O, CO2)traps (absorb and re-emit) theinfrared radiation, increasingthe temperature of theatmosphere…Earth’s atmosphere is slightly warmer than what it should bedue to direct solar heating because of a mild case ofgreenhouse effect…
SUNEARTHThe majority of theradiation is absorbedby the Earth’sSurface with itwarmsSolar radiationPasses throughthe Earth’satmosphereSome Solarradiationredirected byboth the Earth& atmosphereSome of the infraredradiation passesthrough theatmosphere. some isobserved and re-emitted in all directionsby greenhouse gasmolecules. This causesthe earth surface andlower atmosphere towarmInfrared radiation isrealized from theEarth Surface
The Earths AtmosphereOzone
FACT: 15% increase in [CO2] in last 100 years Cause:Change from agricultural to industrial lifestyleBurning of fossil fuels (petroleum, coal)Increase CO2 emissions (cars, factories etc…)Deforestation Effects:Global warmingMelt polar ice caps flooding at sea levelWarming oceans more powerful stormsGreenhouse Effect3503002501000 1500 2000YearAtmosphericCO2(ppm)
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