a metric unit of atmospheric pressure, equal to one million dynes per square centimeter, 100 kilopascal, 750.062 torr 1.019 72 kilograms of force per square centimeter (kgf/cm2), or about 14.503 78 pounds per square inch (lbf/in2). The word comes from the Greek baros, "weighty." We see the same root in our word, barometer, for an instrument measuring atmospheric pressure. One bar is just a bit less than the average pressure of the Earth's atmosphere, which is 1.013 25 bar. In practice, meteorologists generally record atmospheric pressure in millibars (mb). In English-speaking countries, barometric pressure is also expressed as the height, in inches, of a column of mercury supported by the pressure of the atmosphere. In this unit, one bar equals 29.53 inches of mercury (in Hg).
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