WRAL WeatherCenter Blog

On the new design of your site, the barometric pressure shows Hg. What does this mean? I see no reference to the direction such as rising, falling, or steady, as done on the old site design. Margaret

Posted January 15, 2007

MIKE MOSS SAYS:    Margaret,     "Hg" in this case comes from the Periodic Table of the Elements, and is the symbol for mercury, because the pressure value shown on the current conditions page is given in units of inches of mercury, in other words the height of a column of mercury that is balanced by the weight of the column of air above the barometer. Pressure is most commonly stated in terms of inches of mercury, millimeters of mercury, millibars, hectopascals and pounds per square inch. For example, the average sea level pressure for earth is 29.92 inches Hg, 760 mm Hg, 1013.25 mb, 1013.25 hPa, or 14.7 psi.

We will look into adding a pressure tendency statement to the current conditions listing.

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