Barometric pressure

Atmospheric pressure is the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. It is measured by a barometer, hence it is called Barometric pressure. In an alternate timeline, where John Sheppard travelled 48,000 years into the future, a Hologram of Rodney McKay told him that the barometricx pressure outside had dropped and the winds were getting stronger indicating that a violent storm was coming.