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The atmosphere- Layer that surrounds earth, that is constantly changing. (pg.4)
Composition of Earths Atmosphere • Earth Has 4 Main Systems that Interact • Troposphere • Contains Most Clouds and Weather • Temperature cools are you go higher, 50% of sun’s energy passes through, and 50% is reflected back • Most of the Troposphere’s heat is from earth (convection)
Composition of Earths Atmosphere • Earth Has 4 Main Systems that Interact • Stratosphere • Contains ozone that absorbs most of the sun’s ultraviolet radiation (pg. 7) • Gets warmer as you go up
Composition of Earths Atmosphere • Earth Has 4 Main Systems that Interact • Mesosphere • The coldest part of the atmosphere, temperatures can reach -93 degrees Celsius
Composition of Earths Atmosphere • Earth Has 4 Main Systems that Interact • Thermosphere • Temperatures reach 1,700 degrees Celsius • Filters out X-rays, and Gamma Rays from the sun
Composition of Earths Atmosphere • Ionosphere • Is located in the upper part of the mesosphere and lower part of the thermosphere • Particles can be electrically charged in the atmosphere called ions, at times these ions can radiate light of different colors
Altitude • The higher the altitude, the lower the air pressure. • The lower the altitude, the higher the air pressure.
Temperature • As the temperature goes up, the air pressure goes down. (hot molecules are further apart- less pressure). • As the temperature goes down, the air pressure goes up. ( cold air is more dense than warm air).
Conduction • Transfer of heat through matter by molecular activity • Energy of molecules is transferred through collisions from one molecule to another, heat flowing from high to low temp. • Metals are good conductors • Air is a very poor conductor of heat • Conduction is the least significant of the three as a means of heat transfer for the atmosphere
Convection • Most of the heat transport that occurs in the atmosphere is carried on by convection. • Def: The transfer of heat by mass movement or circulation within a substance • Takes place in fluids (oceans, air) where atoms and molecules are free to move about • Pan example: • Warmer water rises, cooler water sinks • Uneven heating of water, from the bottom up • Water will continue to “turn over”, producing a convective circulation
Radiation • Travels in all directions from its source • Travels through the vacuum of space, does not need medium like the other two • Radiation is the heat-transfer mechanism by which solar energy reaches our planet
Greenhouse effect • Approx. 50% of the solar energy that strikes the top of the atmosphere reaches Earth’s surface and is absorbed • Most of this energy is then reradiated skyward • The radiation that it emits has longer wavelengths than solar radiation (terrestrial radiation) • The atmosphere is an efficient absorber of this type of radiation (85% absorbed) • Water vapor and CO2 are the principal absorbing gases • The absorbed terrestrial radiation is then reradiated back to Earth • Atmosphere acts like a real Greenhouse (with windows open)
Global Warming • Carbon dioxide in the atmosphere absorbs some of the radiation emitted by Earth and thus contributes to the greenhouse effect • Changes in content of CO2 could influence air temperature • Rapid growth of industrialization, burning of fossil fuels has added vast quantities of CO2to the atmosphere • The clearing of forests also contributes substantially. Carbon dioxide is released as vegetation is burned or decays
Consequences of Global Warming? • Probable rise in sea level? • Shifts in the paths of large-scale storms, affecting the distribution of precipitation and the occurrence of severe weather • Stronger tropical storms • Increases in the frequency and intensity of heat waves and droughts • Gradual environmental shift, imperceptible to public. Nevertheless will have a strong impact on future economics and thus leading to social and political consequences.
Wind • Wind moves from high areas of pressure to low areas of pressure • Moves from West to East across the U.S.
CORIOLIS FORCE • Pressure gradient wind blows from high pressure towards low pressure. • The earth’s rotation diverts this wind direction laterally. This force is called the CORIOLIS FORCE. • The Coriolis force diverts wind the right in the northern hemisphere; to the left in the south. High Actual wind which blows, as diverted by Coriolis Force Low
PRESSURE BELTS Rising air at the equator causes the equatorial belt of low pressure Descending air at about 30ºN and 30ºS causes the sub-tropical belt of high pressure Polar high pressure Mid latitude low pressure Sub-tropical high pressure Rising air at about 60ºN and 60ºS causes a mid-latitude belt of low pressure Equatorial low pressure Descending air at the poles causes the polar high pressure areas Sub-tropical high pressure Mid latitude low pressure Polar high pressure
Different Winds • Trade Winds • These are in both hemispheres and blow from 30 degrees latitude to the equator. (pg. 16) • Westerlies • Wind belts found in both north and south hemispheres between 30 and 60 degrees latitude. They flow towards the poles in opposite directions of the trade winds. (pg. 17)
Different Winds • Polar Easterlies • They extend from the poles to the 60 degree latitude in both hemispheres. (pg. 17) • Jet Streams • High speed narrow belts that blow in the upper troposphere and lower stratosphere. • Speeds can reach up to about 310 mph. • Local Winds • Are influenced by the geography of an area. (pg. 18)
Pollutants • Primary Pollutants are put here on earth by human or natural activity. • Exhaust, ash from volcanic eruptions, soot from smoke stacks. • Secondary Pollutants are formed from chemical reactions. • Many secondary pollutants are formed when a primary pollutant reacts with sunlight • Acid Raid, Smog
Have Regulations Helped? • In 1997, the emissions of the five major primary pollutants in the United States were about 31 percent lower than 1970. • In 1990, Congress passed the Clean Air Act Amendments, which further tightened controls on air quality. • Regulations and standards regarding the provisions of the Clean Air Act Amendments of 1990 are periodically established and revised.