Meteorology
Atmospheric pressure
At a glance
Meaning of Atmospheric pressure
Pressure exerted by the air, used in setting a barometric altimeter.
More about Atmospheric pressure
Atmospheric pressure results from the weight of the air above a point and varies with altitude and weather. A barometric altimeter uses pressure to indicate altitude.
QNH relates the indication to mean sea level. The standard setting of 1013.25 hPa is used for flight levels where prescribed.