Atmospheric pressure, also known as
barometric pressure (after the
barometer), is the
pressure within the
atmosphere of Earth. The
standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325
Pa (1,013.25
hPa; 1,013.25
mbar), which is equivalent to 760
mm Hg, 29.9212
inches Hg, or 14.696
psi.
[1] The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth, that is, the Earth's atmospheric pressure at sea level is approximately 1 atm.
In most circumstances, atmospheric pressure is closely approximated by the
# 1. 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, resulting in a pressure of 10.1 N/cm2 or 101
kN/m2 (101 kilopascals, kPa). A column of air with a cross-sectional area of 1 in2 would have a weight of about 14.7 lbf, resulting in a pressure of 14.7 lbf/in2.
The bolded and larger font is noticed to the information and (dis)honour for Polymath257 who ridicules me when I´m referring to this scientific subject.
# 1. Hydrostatic Pressure:
(PDF) The Hydrostatic Force (F_H) of Gravity (The Atmospheric Force of Gravity) | Mahmoud E . Yousif - Academia.edu
Hurricane formation, motion and pressure.
Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator. The warm, moist air over the ocean rises upward from near the surface. Because this air moves up and away from the surface, there is less air left near the surface. Another way to say the same thing is that the warm air rises,
causing an area of lower air pressure below.