Barometric pressure of under 29.50 inches of mercury at sea level is considered low. At sea level, a normal barometer reading is between about 29.70 inches of mercury and 30.20 inches. More » Science Earth Science Atmosphere

Barometric pressure, or air pressure, is lowest at high altitudes. However, barometric pressure also varies according to the weather. The lowest barometric pressures have been recorded during strong tropical cyclones. More » Science

Normal barometric pressure is typically around 101.325 kPa / 1013.25 mbar / 760 mmHg / 29/921 inHg. Pressure rarely increases or decreases more than 1 inch of mercury (3.386 kPa / 33.86 mbar / 25mmHg) above or below the ... More » Science Weather & Tides Weather Forecasts
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Barometric pressure was discovered in about 1644 when physicist and inventor Evangelista Torricelli invented the first mercury barometer. Torricelli was an assistant to Galileo Galilei who suggested that Torricelli try u... More » History Inventions

The normal air pressure at sea level is 14.7 pounds per square inch. Standard atmospheric pressure can also be expressed using different units, including 1013.25 millibars, 1013.25 hectoPascals, 760 millimeters of mercur... More » Science Earth Science Atmosphere

Air pressure, the force exerted on a mass by the weight of air particles, is measured in either inches of mercury or in millibars, represented by inHg and mb, respectively. One standard atmosphere, represented by the sym... More » Science Earth Science Atmosphere

Low barometric pressure is caused by warm air from the planet's surface rising, decreasing the amount of air pulled downward by Earth's gravity. This rising heat can lead to adverse weather conditions. More » Science Weather & Tides