Atmospheric pressure

Atmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth (or that of another planet). In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. Pressure measures force per unit area, with SI units of Pascals (1 pascal = 1 newton per square metre, 1 N/m2). On average, a column of air with a cross-sectional area of 1 square centimetre (cm2), measured from mean (average) sea level to the top of Earth's atmosphere, has a mass of about 1.03 kilogram and exerts a force or "weight" of about 10.1 newtons or 2.37 lbf, resulting in a pressure at sea level of about 10.1 N/cm2 or 101 kN/m2 (101 kilopascals, kPa). A column of air with a cross-sectional area of 1 in2 (6.45 cm2) would have a mass of about 6.65 kg and a weight of about 65.4 N or 14.7 lbf, resulting in a pressure of 10.1 N/cm2 or 14.7 lbf/in2.

Mechanism

Atmospheric pressure is caused by the gravitational attraction of the planet on the atmospheric gases above the surface, and is a function of the mass of the planet, the radius of the surface, and the amount of gas and its vertical distribution in the atmosphere.[1][2] It is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition.[citation needed]

Other Languages
Afrikaans: Lugdruk
العربية: ضغط جوي
azərbaycanca: Atmosfer təzyiqi
Bân-lâm-gú: Khì-ap
беларуская: Атмасферны ціск
беларуская (тарашкевіца)‎: Атмасфэрны ціск
Deutsch: Luftdruck
eesti: Õhurõhk
Esperanto: Atmosfera premo
فارسی: فشار جو
한국어: 대기압
Bahasa Indonesia: Tekanan atmosfer
íslenska: Loftþrýstingur
magyar: Légnyomás
Bahasa Melayu: Tekanan atmosfera
Nederlands: Luchtdruk
日本語: 気圧
norsk nynorsk: Lufttrykk
oʻzbekcha/ўзбекча: Atmosfera bosimi
Simple English: Atmospheric pressure
slovenčina: Atmosférický tlak
slovenščina: Zračni tlak
srpskohrvatski / српскохрватски: Atmosferski tlak
suomi: Ilmanpaine
svenska: Lufttryck
українська: Атмосферний тиск
Tiếng Việt: Áp suất khí quyển
文言: 氣壓
粵語: 大氣壓力
中文: 气压