For GSS Ozone chapter 9. Excerpt: The ozone hole that forms each year
in the stratosphere over Antarctica was slightly smaller in 2013 than
average in recent decades, according to NASA satellite data. ...However,
the size of the hole in any particular year is not enough information
for scientists to determine whether a healing of the hole has begun.
...The ozone hole forms when the sun begins rising again after several
months of winter darkness. Polar-circling winds keep cold air trapped
above the continent, and sunlight-sparked reactions involving ice clouds
and chlorine from manmade chemicals begin eating away at the ozone.
Most years, the conditions for ozone depletion ease before early
December when the seasonal hole closes. See image.... http://www.nasa.gov/press/2013/october/antarctic-ozone-hole-slightly-smaller-than-average-this-year/. NASA RELEASE 13-316. |
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