Chapter 13 Notes - The Atmosphere and Weather Atmosphere is...

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The Atmosphere and Weather Atmosphere is the thin layer of gases that surrounds the earth. o Provides us with oxygen, absorbs hazardous solar radiation, burns up incoming meteors, transports and recycles water and nutrients, and moderates climates o Consists of 78% nitrogen gas 21% oxygen gas 1% argon gas o Some of which are permanent gases (remain at stable concentrations) or variable gases (vary in concentration from time to time) Atmosphere chemical composition has changed over time. Human activity is altering the quantities of some atmospheric gases o Carbon Dioxide o Methane o Ozone The Atmosphere is Layered Is a thin coating about 1/100 of earths diameter, like the fuzzy skin of a peach. Coating consists of four layers o Trophosphere Bottommost layer Blankets earth surface Provides with air we need to live Air within troposphere responsible for the planets weather Contains ¾ of the atmospheres mass, as air is denser near earth’s surface Troposphereic air temperature declines 6’C for each km in altitude. At the top of the troposphere, temperatures decline with altitude, marking a boundary called tropopause ( upper boundary of trophosphere, limits mixing between troposphere and the stratosphere o Stratosphere extends from 11km and 50km above sea level 1000 times as dry and less dense then troposphere Gases experience little vertical mixing, so when pollutants enter they stay for a long time Attains a max temperature of -3’C at its highest altitude, is colder in its lower reaches Because the ozone and oxygen absorb and scatter the suns ultraviolet radiation so that much of the UV radiation penetrating the upper stratosphere fails to reach the lower stratosphere Ozone layer contains most of the atmospheres minute amount of ozone from 17km to 30km above sea level Reduces the amount of UV radiation that reaches the earths surface UV light can damage living tissue and induce mutations in DNA Its protective effects are vital for life on earth
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o Mesosphere Extends from 50km to 80km above sea level Air pressure is low Temperatures decrease with altitude, reaching their lowest point at the top of the mesosphere. o Thermosphere is the top layer and extends upward to an altitude of 500km Atmospheric properties include temperature, pressure, and humidity Differences in air masses allow movement in the lower atmosphere o These properites include pressure, density, relative humidity and temperature Gravity pulls down gas molecules toward earth’s surface o Air is therefore more dense at the surface and less as altitude increases. Atmospheric pressure is the force per unit area produced by a column of air, and also decreases with altitude because at higher altitudes, fewer molecules are pulled down by gravety. relative humidity
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This note was uploaded on 02/29/2012 for the course ENVIRONMEN eesa01 taught by Professor Mitchel during the Fall '11 term at University of Toronto- Toronto.

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Chapter 13 Notes - The Atmosphere and Weather Atmosphere is...

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