Introduction <ul><li>The air is always moving. Convection currents and wind keep air circulating around the Earth. Even polluted air moves away and becomes replaced by fresh air. But sometimes the air isn't able to circulate which is how pollutants accumulate. It accumulates due to the natural process of nature for billions of years. The accumulation of pollutants kills hundreds of thousands of people each year around the world. </li></ul>
Air pollution? <ul><li>Air pollution is toxics that get stuck in one area for too long and start to clump together, it causes many health and environmental problems. </li></ul>
Sources and Causes <ul><li>When we talk about air pollution, it means gasses and dust in the atmosphere that don't occur naturally. </li></ul><ul><li>Air pollution comes from natural and manmade sources. But the main cause is manmade pollutants, for example: construction, mining, agriculture, nuclear power plants, oil tankers, and most importantly cars. </li></ul><ul><li>The explosion of the population, is also a factor contributing toward the growing air pollution problem. </li></ul>
Environmental Issues and Weather Patterns <ul><li>Pollution is a consequence for natural disaster. For example hurricanes which involve water contamination from sewage, and oil spills from ruptured boats or automobiles. </li></ul><ul><li>Scientists observing a NASA satellite say that air pollution from humans is likely to cause more rainfall and storms in the South-eastern United States. </li></ul>
Air Convection and Currents <ul><li>Air currents are the continuous movement of air transferring heat from the equator to the poles and vice-versa. At the equator heated, moist air flows upwards. </li></ul><ul><li>They are caused by the differences in temperature and pressure. Temperature differences can cause air currents because warmer air is less dense than cooler air, causing the warmer air to appear “lighter”. So if the warm air is under the cool air, air currents will form as they exchange places. </li></ul><ul><li>Pressure differences also cause air currents as the air flows from areas of higher pressure to areas of lower pressures, and hot air rises. </li></ul>
Convection Currents <ul><li>An example of convection currents are birds who float upward on rising currents towards the warm air. </li></ul><ul><li>Convection currents help disperse air, including any pollutants in the air. This natural force moves polluted air rising and dilutes it in less-polluted air above. Due to convection, air pollution doesn't remain isolated or localized. But a temperature inversion can change normal convection currents. </li></ul><ul><li>Convection currents are always hot rising and cool falling. </li></ul>
How do Temperature Inversions Form? <ul><li>Temperature inversions play a huge role in the air quality. A temperature inversion occurs when a mass of warm air moves over a cooler, surface air. This warm air forms a lid over the area, trapping all the polluted air left from the city’s transportation systems, industries, and homes. The inversion traps pollutants near the ground, leading to poor air quality. If a temperature inversion traps pollutants, then a visible layer of smog will appear. </li></ul><ul><li>During the day time, the sun heats the surface of the Earth and the layer of air closest to the Earth. This warm air rises and mixes with other atmospheric gases. When the sun goes down a temperature inversion takes place. The less dense warm air thats high up provides a blanket for the colder air. The colder air is trapped close to the Earth because it's less dense and the atmospheric gases don't mix. </li></ul>
Smog <ul><li>In busy cities like San Francisco you can sometimes see haze that forms over the city. Sources include motorized vehicles, industries, airplanes, trains, wood stoves, and wildfires. Smog occurs due to convection currents becoming effected from temperature inversions. </li></ul><ul><li>Smog usually stays until the morning sun warms the air enough to begin the mixing of the convection cycle. </li></ul>
Work Cited Page <ul><li>http://www.cite-sciences.fr/lexique/definition1.php?lang=an&id_expo=13&id_habillage=24&iddef=456&idmot=168 </li></ul><ul><li>"Air Currents ." Resources and Lexicon (2004) <http://www.cite-sciences.fr/lexique/definition1.php?lang=an&id_expo=13&id_habillage=24&iddef=456&idmot=168>. </li></ul><ul><li>http://en.wikipedia.org/wiki/Pollution </li></ul><ul><li>Everyone. "Pollution." Wikipedia. 2001. Jimmy Donal. 13 December 2001 <http://en.wikipedia.org/wiki/Pollution>. </li></ul><ul><li>http://maps.grida.no/go/graphic/dominating_air_currents </li></ul><ul><li>"Dominating air currents." UNEP/GRID-Arendal Maps and Graphics Library. Unknown. UNEP/GRID-Arendal. 5 Feb 2009 </li></ul><ul><li>http://www.sciencedaily.com/releases/2008/02/080201215416.htm </li></ul><ul><li>NASA/Goddard Space Flight Center. "Air Pollution May Be Causing More Rainy Summer Days In The Southeast US." ScienceDaily 7 February 2008. 4 February 2009 <http://www.sciencedaily.com/releases/2008/02/080201215416.htm> </li></ul><ul><li>http://www.newton.dep.anl.gov/newton/askasci/1995/environ/ENV114.HTM </li></ul><ul><li>Mortis. "Cause of Air Pollution." Ask A Scientist 4 February 2009 <http://www.newton.dep.anl.gov/newton/askasci/1995/environ/ENV114.HTM>. </li></ul><ul><li>http://www.weatherquestions.com/What_is_a_temperature_inversion.htm </li></ul><ul><li>http://www.infoplease.com/ce6/weather/A0848126.html </li></ul>
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