kenzie earth 3

kenzie earth 3 - Lecture 4, Chapter 2 The Ozone Hole Until...

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Lecture 4, Chapter 2 The Ozone “Hole” Until the 20 th century, ozone levels had been relatively stable for several hundred million years. Now it is in a state of continuous change The ozone layer is thinning, particularly in the upper latitudes. This thinning is called a “hole” although it isn’t a total hole. The hole is caused by chlorine atoms that decompose ozone. These atoms are coming from CFC’s, which are human made molecules that have chlorine in them that were widely used in aerosoles, refrigerants, foaming agents, and solvents. They migrate into the stratosphere, where UV radiation splits them, freeing chlorine atoms. The chlorine can destroy ozone, turning it into oxygen gas. Why CFCs from the Northern Hemisphere end up concentrated over the South Pole for two reasons: 1. During the long cold winter months, a polar vortex forms over Antarctica. It doesn’t mix much with the lower atmosphere, and chemical reactions are enhanced in this enclosed air mass. (Over the North Pole, conditions are more changeable, so the hole is smaller). 2.
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kenzie earth 3 - Lecture 4, Chapter 2 The Ozone Hole Until...

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