Aerosols

     Aerosols are solid or liquid particles suspended in a gas, usually air. There are many types of aerosols, lots of which are man-made and likely what the average person thinks of when hearing the term--hairspray, air freshener, and the like. But the vast majority of aerosols are natural, ranging from the water found in clouds to dust found in dry regions of the world to sea salt from ocean spray. These are part of a planet-wide system of weather patterns which have always existed and which significantly shape the climate of every part of the earth. Many others are natural in origin, but caused by human behaviors--huge amounts of sulfate from burning fossil fuels and black carbon and organic carbon from "biomass burning" (clearing land or getting rid of farm waste).

     The primary ways these particles affect the climate is by changing the levels of solar radiation which reach the earth, either by reflecting radiation back into space or by preventing it from leaving the atmosphere once it enters. These changes can have the net effect of cooling the earth and of heating it, respectively. This makes the process of predicting climate change difficult, because while some atmospheric variables, like greenhouse gases, are well-understood and fairly consistent, the effects of the changing levels of man-made aerosols are highly varied and difficult to predict.

     This means that the long-term effect of aerosols on earth's climate is difficult to pinpoint. There are, however, other ways that they affect daily life. A change in the level of aerosols in a given area can affect visibility, as in city smog or the recently noted haze over places like the Grand Canyon. Certain man-made aerosols can be damaging when breathed in. And some of the "propellants", or base gases, once used in canned aerosol sprays contributed significantly to the thinning of the ozone layer. These propellants, called fluorocarbons, have been almost universally banned, but their effects are still being felt today.

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sources:
http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/aerosol&climate.html
http://www.eoearth.org/article/Aerosols#gen4
http://earthobservatory.nasa.gov/Features/Aerosols/
http://en.wikipedia.org/wiki/Particulates
http://en.wikipedia.org/wiki/Aerosol

Group Work

Three things that worked in my group:

• Everyone got along well.
• Everyone did some work--my group members almost without exception knew what was going on and were willing to do something if it was asked of them.
• Our presentation was the best in the business.

And three things that didn't:

• Our time management wasn't great. We had a few days where no one did anything and one or two where we worked really hard to get it finished in time, and we had to finish up our powerpoint during presentation week.
• I was kind of bossy/controlling. Old habits die hard, and I'm kind of a perfectionist, but I think I should have respected others' choices and work more and done less "management".
• We didn't always allocate the work very well--some people did much more, others less. 

Surface Ozone

Ozone is a chemical made up of three oxygen atoms. It is most often found in the upper atmosphere, where it is created naturally when energy from the sun breaks oxygen molecules (O2) in half and binds each atom to another O2 molecule. This form of ozone is good for the earth; it protects us from harmful UVB rays, which can damage crops and cause skin cancer.

Another form of ozone, however, is less benign. Called surface ozone, it is created in the lower atmosphere by chemicals like volatile organic compounds and Nitrogen oxides (VOCs come from various man-made chemical products like cleaners and paint, while NOx are created by combustion, as in car engines) and is corrosive, damaging plants, animals, and people. It can cause permanent lung damage in people who breathe it repeatedly. And what's more, it's pervasive, because the chemicals which create it come from the burning of fossil fuels, something that western society is completely dependent on and which no one can avoid doing in some aspect of their lives, whether driving, using electricity, or heating one's house.

Because of the dangers of "bad" ozone and its ubiquity, it's extremely important that we study it to figure out how to reduce it or protect against its effects. The role it plays in air pollution is significant and unavoidable, so we must learn as much as we can.