Dear Tom,
Are there hurricanes in the Southern Hemisphere? By the way, why are hurricanes seasonal?
Mitch Saranow, Winnetka
Dear Mitch,
Hurricanes do indeed occur in the Southern Hemisphere. Hurricane breeding grounds include all areas of the world ocean whose surface water temperatures climb to the upper 70s or higher. Widespread 80-degree water temperatures are necessary for strong tropical storm development.
Hurricanes require a vast amount of heat energy that is available in sufficient quantity only from very humid air that develops over warm ocean waters. The peak of the hurricane season in each hemisphere therefore jibes with the peak of ocean temperatures–early autumn in both hemispheres. Consider this: The 150 m.p.h. winds of Cyclone (hurricane) Tracy devastated Darwin, Australia, on Christmas 1974.
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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.
