Air & Atmosphere Review


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  • Average lung capacity is 5,000 cm3
  • Average lung capacity is 5,000 cm3
  • At one time, automobiles were a huge source of carbon monoxide pollution. Automobiles require so much energy that they burn gasoline at a very fast rate. The gasoline is burned so quickly that there is just not enough time to supply it with plenty of oxygen. As a result, incomplete combustion occurs and carbon monoxide is produced. In 1977, however, the U.S. government required car manufacturers to install catalytic (kat' uh lih tik) converters in all new cars. These devices convert more than 95% of the carbon monoxide produced by automobiles into carbon dioxide. After the government mandated this change in automobile manufacturing, the concentration of carbon monoxide in the air began to decline rapidly.
  • The stratosphere is very dry; air there contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere. Polar stratospheric clouds (PSCs) are the exception. PSCs appear in the lower stratosphere near the poles in winter. They are found at altitudes of 15 to 25 km (9.3 to 15.5 miles) and form only when temperatures at those heights dip below -78° C. They appear to help cause the formation of the infamous holes in the ozone layer by "encouraging" certain chemical reactions that destroy ozone. PSCs are also called nacreous clouds.
    Due to the lack of vertical convection in the stratosphere, materials that get into the stratosphere can stay there for long times. Such is the case for the ozone-destroying chemicals called CFCs (chlorofluorocarbons). Large volcanic eruptions and major meteorite impacts can fling aerosol particles up into the stratosphere where they may linger for months or years, sometimes altering Earth's global climate. Rocket launches inject exhaust gases into the stratosphere, producing uncertain consequences.
  • Air & Atmosphere Review

    1. 1. Atmosphere & Air Review Earth’s Pr o tective Bla nket
    2. 2. Earth's Atmosphere What's an atmosphere?  Air surrounding a planet  Earth's atmosphere has 5 layers  Different planets have different layers and different gases in their atmospheres What does it do?  Protects from Sun's heat (and space's cold)  day/night temps would be extreme without blanket of gases  Protects from Sun's harmful rays  solar (ultraviolet) radiation would destroy all life if not filtered out Exosphere Thermosphere Mesosphere Stratosphere Troposphere
    3. 3. Layers Identified by Temperature Temperature changes determine layers Top region and transition to next layer called:  Tropopause Mesopause  Stratopause  Mesopause Stratopause Tropopause
    4. 4. Earth's atmosphere, a mixture of gases: • N2, O2, Ar, CO2, and others gases plus water vapor, dust, etc. •Earth's gravity holds more air molecules near it's surface than in the upper atmosphere where gravitational forces are weaker
    5. 5. Atmospheric Pressure Higher altitudes=  Fewer molecules pushing on each other and their surroundings  Lower pressure  Less concentrated oxygen levels
    6. 6. Density Amount of matter within a specific volume   # of atoms occupying a particular space how close together the atoms are packed SI base units = g/cm3 or g/ml
    7. 7. Altitude & Density  As air pressure decreases, density of air also decreases  Air particles are not squashed together as tightly the higher one goes (because of gravity) Air at sea level and 8km both have 21% oxygen  But 21% of 100 = 21, while 21% of 10 is only 2!  At 8km there are fewer molecules per cubic cm, so you take in less oxygen with each
    8. 8. Evaporative Cooling When droplets of sweat evaporate from your skin, they take a lot of heat with them, and your body is thus colder because it has lost heat energy.
    9. 9. Layers of Earth’s Atmosphere  Troposphere  Where we live  Stratosphere  Ozone layer  Mesosphere  Meteors burn up  Thermosphere  Space shuttle  Aurora Borealis  Exosphere  Thin, outer layer  Beginning of outer space Exosphere
    10. 10. Troposphere  Thinnest layer (4 to 12 miles thick)  Thickness depends on terrain, season, time of day & latitude  Holds ~80% of Earth's atmospheric mass  Highest pressure at lowest levels  Most weather occurs here  Water vapor (& clouds), wind, lightning  Jet stream (river of 250 mph winds) is just below the Tropopause (upper boundary) or in the lowest parts of the stratosphere  Temperature cools as you go up  Sun heats ground, which radiates warmth to air above it  Air is warmest near the ground  Air cools ~6.4oC  14oC (57oF) every 1 km you go up Top of Troposphere is -50oC (-58o F)
    11. 11. Greenhouse Effect  Solar radiation that reaches earth is absorbed by:  Earth's surface (50%)   land heats quicker and radiates sooner bodies of water heat slower and hold onto heat longer  Earth's atmosphere (15%)  35% of Solar radiation is reflected from  Earth's atmosphere  Clouds  Earth's surface (i.e. snow, sand)  Some of the heat absorbed by Earth's surface is released into the atmosphere
    12. 12. Air Pollution  Nitrogen Oxides  Damage lung tissue  Sources:   car, plane, mower engines lightening burning N2 in air  Sulfur Oxides  Damage lung tissue  Sources:   burning coal volcanic eruptions  Carbon Monoxide  Causes asphyxiation  Sources:   gasoline engines (automobiles, chainsaws, trains, etc.) forest fires, woodstoves, cigarettes  Airborne Lead  Destroys brain tissue  Source: leaded gasoline  Particulates
    13. 13. Stratosphere  Thickness from 33 to 40 km (20-25 miles)  Depends on Troposphere's thickness  Top boundary (Stratopause) at 50km above sea level  Contains the Ozone Layer  Earth's "sunscreen"  Temperatures rise as you go up  Heat trapped by ozone warms layer  -50oC to -3oC to (-58o to 27o Fahrenheit)  Very stable/stagnant layer  Little to no wind (not much mixing)  Jet aircraft fly lower stratosphere  No water vapor/clouds (very dry)
    14. 14. Ozone Layer O3 Molecules Absorbs UV light which cause skin cancer & cataract Absorbs heat Toxic to breathe
    15. 15. "Hole" in the Ozone Layer Chlorine & Bromine bind to oxygen & deplete ozone Mostly at the south pole where Artic winds carry Cl & Br up into the Stratosphere Localized & seasonal "thinning" - not a complete "hole" CFCs in refrigerants Montreal Protocol Studies now show reversal Some models predict reversal will increase global warming
    16. 16. Global Warming Average global temperatures have increased by about 1oC over the past 150 years. How do we know this?
    17. 17. The Big Picture
    18. 18. Causes of Global Climate Change Greenhouse gases  Carbon Dioxide  Methane  Nitrous Oxide  Water Vapor Solar activity Earth's elliptical orbit Volcanic Eruptions
    19. 19. Transfer of Heat Energy
    20. 20. Conduction Heat moving through molecules Molecules bumping into each other transfers heat What make good conductors? gases are poor conductors metals are good conductors Animation
    21. 21. Convection  Heat moves with the molecules as they flow - Warmer molecules move faster and push each other apart - Less dense particle masses rise up, leaving space - As molecules lose heat, they sink back down, creating a circular flow  Gas and liquids only  Animation
    22. 22. Radiation  Does not involve matter (atoms)  Can travel through space (vacuum)  Electromagnetic waves carry heat  Different wavelengths  visible light  infrared light  ultraviolet light  Sun, flame, light bulb or other heat source
    23. 23. Atmospheric Convection Concentrated solar radiation at equator = hotter air (re- radiation)  Rising heated air masses creates low pressure areas (L) Cold air from poles sinks down  Denser (colder) air molecules results in high pressure areas (H) H L
    24. 24. Convection Cells Sinking polar air reaches warmer 60o latitudes and rises  Poles are high pressure areas (90o N & S) Rising equatorial air reaches cooler 30o latitudes and sinks  Equator is low pressure area L In between (temperate latitudes)  Airflow in reverse directions H because of H's & L's Ultimate source of air L movement (wind) on Earth:  Uneven heating of earth’s surface H
    25. 25. Coriolis Effect The perceived curving of global winds due to Earth's rotation Video Illustration  Each cell curves (seemingly)  N. hemisphere curves right (clockwise)  S. hemisphere curves left (counter-clockwise)  Polar matter rotates slower than equatorial matter: greater effect near equator
    26. 26. Global Winds Trade Winds North & South of the Equator Blow from East to West Prevailing Westerlies Latitudes 30 to 60 Named for the direction from which they blow Polar Easterlies North & South Poles Weak & irregular
    27. 27. Sea and Land Breezes Sea Breeze  Daytime:  Land heats up faster than water  Hot air over land rises (L)  Cool air over water pushes onto land (H) Land Breeze  Nighttime:  Land cools faster than water  Warm air over water rises (leaving a low pressure area)  Cool air over land pushes into low pressure area over water
    28. 28. Jet Streams High up in atmosphere Upper Troposphere Lower Stratosphere Form between cold & warm air masses bigger temperature difference = faster jet stream winds Flow west to east around the globe