Atmospheric Pressure

Atmospheric pressure

Atmospheric pressure, also known as air pressure or barometric pressure, is the pressure within the atmosphere of Earth. The standard atmosphere is a unit of pressure defined as 101.325 kPa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, 760 torr, about 29.9212 inHg, or about 14.696 psi. The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, Earth's atmospheric pressure at sea level is approximately one atm.

Atmosphere

An atmosphere is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. The name originates from Ancient Greek ἀτμός (atmós) 'vapour, steam' and σφαῖρα (sphaîra) 'sphere'. An object acquires most of its atmosphere during its primordial epoch, either by accretion of matter or by outgassing of volatiles. The chemical interaction of the atmosphere with a solid surface can change its fundamental composition, as can photochemical interaction with the host star. A body retains an atmosphere for longer durations when the gravity is high and the temperature is low. The stellar wind works to strip away a body's outer atmosphere, although this process is slowed by a magnetosphere. The further a body is from its star, the lower the rate of atmospheric stripping.

Pressure

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.

atmospheric pressure

Noun

1. The pressure caused by the weight of the atmosphere above an area.