Dear Tom,
Why is the largest hole in the Earth’s ozone layer located above Antarctica, even though no people with CFCs or other pollutants permanently live there?
Jason Lewitzke, Grayslake, Ill.
Dear Jason,
The atmosphere is so well mixed that any pollutant (like ozone-destroying CFCs) put anywhere into the atmosphere will eventually distribute itself worldwide.
Triton College astronomer Dan Joyce explains that atmospheric ozone forms when oxygen molecules are bathed by the ultraviolet component of sunlight, but given that the polar atmosphere is so often in shadow or that the sun’s rays are slanted even during daylight, ozone production is limited at the poles.
In addition, Antarctica is very high–its average elevation is 8,200 feet–and the depth of atmosphere available for ozone production is much more limited there than at the North Pole.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Pl., Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
