Dear Mr. Skilling,
Is the atmospheric pressure that is reported the same value that pilots get when they ask for the altimeter setting? Is this pressure corrected to sea level?
Barry Wallis, Downers Grove
Dear Barry,
The barometric pressures that you hear reported are indeed the same readings used by pilots and are reduced to sea levelwhich means they have been corrected for the elevation of the reporting weather station’s barometer. If a conversion to sea level were not done, mountain locations would always have low barometer readings.
More and more of the weather readings which are disseminated originate from automated weather observing stations (known as ASOS stations). Those stations, says Bob Collins, the National Weather Service’s chief data acquisition manager here in Chicago, actually have three barometers that cross check one anotherassuring the accuracy of the reported barometric pressure readings.
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Tom Skilling is chief meteorologist at WGN-TV. His weather forecasts can be seen Monday through Friday on WGN News at noon and 9 p.m.
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