Dear Tom,
Is the atmosphere spinning at the same speed as the Earth is turning?
Carl Brace
Dear Carl,
The atmosphere rotates with the Earth, or very nearly so, simply because friction between air and the unyielding ground keeps the atmosphere relatively “locked in place.” And it’s good that this is so. The Earth’s axial spin, one complete rotation in 24 hours, translates into surprisingly great speed on the surface of a sphere as massive as the Earth. At Chicago’s latitude (41(degrees), 47’N at Midway Airport), the Earth’s surface is moving (toward the east) at about 770 m.p.h., or 13 miles per minute. If the atmosphere were absolutely stationary relative to a viewer looking down on the Earth from space, then we here in Chicago would experience a steady east wind roaring at 770 m.p.h.
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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.
