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GG101 Chapter 3 Notes.docx

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James Hamilton

GG101 Chapter 3 Notes Earth’s Modern Atmosphere Atmospheric Composition, Temperature and Function  Air is a simple mixture of gases that is naturally odourless, colourless, tasteless, and formless  The Lives of a Cell: compares Earth’s atmosphere to an enormous cell membrane  Exosphere: Outer Sphere where rarefied atmosphere is nearly a vacuum  The Atmosphere represents under one-millionth of Earth’s total mass o A series of imperfectly shaped concentric “shells” or “spheres” that grade into one another, all bound to the planet by gravity o Earth’s Atmosphere exerts weight, pressing downward under the pull of gravity o The weight or AIR PRESSURE pushes in on all of us o Atmosphere exerts an average force of approximately 1kg/cmsq at sea level o Air pressure skyrockets exponentially as we move up in height  Heterosphere: outer atmosphere in terms of composition; begins at about 80km (50mi) altitude and extends outward to the exosphere and interplanetary space transition  Gases in heterosphere occur in distinct layers sorted by gravity according to their atomic weight  Homosphere: below heterosphere; rapidly changing density; includes oxygen, o Air is a vast reservoir of relatively inert NITROGEN, originating principally from volcanic sources o Nitrogen is a key element of life o Oxygen is also essential for life processes; forms 1/5 of atmosphere but also, compounds that compose ½ of Earth’s crust; roughly 21% by volume (dry air) o Argon: less than 1% of atmosphere; useless for organisms, mined from atmosphere for commercial/industrial purposes- a noble gas that is very stable o Carbon dioxide concentrations skyrocketed thanks to industrialization- new gases have emerged in tiny concentrations yet affect our atmosphere Atmospheric Temperature Criterion  Thermosphere: 250-480 km above earth; temperatures rise to 1200 degrees C and higher; o Kinetic (motion) energy is generated as sensible heat, measured as temperature o Actual involved heat is small,  Mesosphere: 50-80km above earth, within Homosphere; averages -90 degrees C, ice crystals glow in rare and unusual night noctilucent clouds  Stratosphere: 18-50km above earth, from -57 to 0 degrees C  Troposphere: final layer encountered by incoming solar radiation as it surges through atmosphere to the surface; SUPPORTS LIFE ON EARTH o Tropopause: upper limit, varied exact altitude o Normal Lapse Rate: rate at which temps decrease, 6.4 deg C per KM o Environmental Lapse Rate: deviations due to local weather conditions  Ionosphere: outer functional layer that extends throughout the thermosphere and into the mesosphere below  Ozonosphere: portion of the stratosphere that contains an increased level of ozone is the ozonosphere o Made up of three oxygen atoms o Relatively stable before industrialization, however it now changes continually Variable Atmospheric Components Air Pollution…  Natural Air poll
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