Our Changing Atmosphere

Force & Motion
Earth & Environment


Weather & Climate
Notes & Review Ch. 26 – 28
Our Changing Atmosphere
Wind Zones – Notes
Notes & Review Ch. 29 – 30
Storms – Natural Disasters
Notes & Review Ch. 31
Weather & Climate Review








Our Changing Atmosphere

  The atmosphere of the early Earth would have been unable to support life, due to its lack of oxygen. In addition, it would have been toxic to us. It had a large component of volcanic gases in it, including a huge amount of carbon dioxide, as well as carbon monoxide, methane, sulfur dioxide, hydrogen, water vapor, and many others. About the time plants expanded their territories onto land, and became much more common on both land and sea, the carbon dioxide levels began to drop and oxygen levels to rise simultaneously, until they reached the levels they are today. Our modern atmosphere, which has been 78% nitrogen, 21% oxygen, and only a trace of water vapor, CO2, and other gases for some time now, is still undergoing gradual change, largely due to human activity. As a consequence of our industrialized societies and our consumption of massive quantities of fossil fuels, we have more than a trace of water vapor and CO2 in our atmosphere now, as well as CO, lead, and particulate matter (ash, soot, and cinders, in spite of our attempts to “scrub” the exhaust of our coal burners before releasing it into the world,) and they are steadily growing. These gases contribute to the Greenhouse Effect, as does the ozone we have released down here in our troposphere. (The ozone up in our stratosphere does not contribute to global warming, but it does protect us from ultraviolet radiation.) We have passed more laws to clean up the air, including banning chlorofluorocarbons (CFC’s) from aerosol cans, to prevent the further destruction of the ozone layer in the stratosphere, and laws requiring that the freon used in air conditioning and refrigeration systems to be kept “closed,” and not released into the atmosphere. Unfortunately the liberal use of styrofoam, whose production is devastating to air quality, and the use of halons in firefighting are just two of the many more ways we still pollute the sir with seemingly little regard for the future.

1.     According to this graph, during which year was the earth’s temperature right about its average (its “long term mean”)?
A.   1890 C.   1945
B.   1915 D.   2000
2.     During which 2 years was it well above average?
A.   1890 C.   1945
B.   1915 D.   2000
3.     What might account for it being so high those two years?

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