BreathIt In!! TheEarthsAtmosphere Whatwillhappen in thefutureifwedon’tchange? AOI: Environments
Contents • Composition of theearthsatmosphere and it’sproperties • Structure of theatmosphere • AtmosphericPressure • Theimportance of theatmosphere • Observingthesky • Atmosphericphenomena • Air pollution
Composition of theatmosphere • Theatmosphereis a gaseouslayerwhichsurroundstheplanet • Itisabout 500 km thick, butmost of the gases are in thetroposphere (0 km to 15 km up) • Air ismainlymade of Nitrogen (78%), Oxygen (21%), Carbondioxide (0.04%), Watervapour ( around 1%) and other gases likeargon (around 1 %)
Composition of theatmosphere • These gases are a mixture becausethey are notchemicallyboundtogether and can be seperated. • For more on gases: http://www.skoool.ie/skoool/junior.asp?id=400
Atmosphericlayers Troposphere • This is where all plants and animals live and breathe • Where weather takes place • Air is mixes • T decreases with altitude
Atmosphericlayers Stratosphere • Ozone in this layer stops many of the sun's harmful rays from reaching the earth • People can not breathe in this layer.
Atmosphericlayers Mesosphere • T decreases with altitude • This is where we see “shooting stars" – meteors burning up as they fall to Earth
Atmosphericlayers Thermosphere • Layer of the atmosphere which is first exposed to the Sun's radiation and so is first heated by the Sun. • The air is very thin • The temperature dependent on solar activity.
Keeping an Atmosphere • Atmosphere is kept by the world’s gravity • Low mass (small) worlds= low gravity =almost no atm. • High mass (large) worlds = high gravity = thick atm. • Gravity and pressure • Air pressure depends on how much gas there is i.e. The atmospheric thickness.
Gravity and Atmospheric Pressure • The stronger the gravity, the more gas is held by the world and the greater the weight of atm. on a point
Gravity pulls the air molecules toward the earth, giving them weight. The weight of the air molecules all around us is called the air pressure.
High altitudes = lower pressure Low altitudes = higher pressure
Atmospheric Pressure Gas pressure depends on both density and temperature. Adding air molecules increases the pressure in a balloon. Heating the air also increases the pressure.
Air pressure is equal in all directions. Pressure = force per unit area
Barometric pressure goes down. As elevation goes up This is an inverse relationship.
Torricelli’s barometer used a glass column suspended in a bowl of mercury. The pressure of the air molecules pushed the mercury up into the glass tube. The weight of the mercury in the tube was equal to the weight of the air pressing down on the mercury in the dish.
As atmospheric pressure increases… The mercury in the tube rises.
The Mercury Barometer Good: Bad: • Simple to construct • Highly accurate • Glass tube is fragile • Mercury is very toxic!
TheGreenhouseeffect • http://www.skoool.ie/content/skoool_learning/junior/lessons/science/conservation/flash/h-frame-ns6.htm • Pages 1-10
TheGreenhouseeffect TheGreenhouseEffectis NOT thesame as Global Warming
TheGreenhouseEffect • Light containsenergy and travelslike a wave
TheGreenhouseEffect • Toomuch light energyisstaying in theatmospherebecause of greenhouse gases likeCarbonDioxide and Methane • Thisismakingtheplanethotteroverall • Thisiscauseingproblemslike: • Flooding (ice capsmelting) • Drought • Destrcuction of habitats and ecosystems