Atmospheric pressure is a fundamental concept in understanding the behaviour of air and its movement patterns, which have a significant influence on our weather and climate.

Definition And Units

‘Atmospheric pressure’ refers to the force exerted by the weight of the air column above a specific point on Earth’s surface. This weight is the result of the gravitational pull acting on the air molecules. The unit commonly used to express atmospheric pressure is the millibar (mbar). At sea level, the average atmospheric pressure is approximately 1,013.2 millibars.

Measuring Instruments

Atmospheric pressure can be measured using different types of barometers.

A mercury barometer consists of a column of mercury in a glass tube; the height of the mercury column adjusts to balance the weight of the air column above it.

An aneroid barometer employs a flexible metal box that compresses or expands with changes in air pressure. Both types offer insights into the current atmospheric pressure and can be used to predict short-term weather changes.

Altitude And Atmospheric Pressure