Other forms: air pressures
The weight of the air in the atmosphere is air pressure. You can measure air pressure using a barometer.
The force with which air is pressed down by gravity is air pressure, also known as atmospheric or barometric pressure. Meteorologists are interested in air pressure, as it's one of the main factors influencing weather. If you measure air pressure at the top of a very tall mountain, it will be lower than it is back down near sea level — this is because of the increasing thinness of the atmosphere at higher altitudes.