What is the low atmospheric pressure?

Atmospheric pressure is sometimes defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most cirstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric m above their location, whereas high pressure areas have more atmospheric m above their location. Similarly, as elevation increases there is less overlying atmospheric m, so that pressure decreases with increasing elevation. A column of air one square inch in cross-section, measured from sea level to the top of the atmosphere, would weigh approximately 14.7 lbf. The weight of a 1 m2 (11 sq ft) column of air would be about 101 kilonewtons (equivalent to a m of 10.2 tonnes at the surface.