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The global mean pressure at the surface of the Earth is PS = 984 hPa, slightly less than the mean sea-level pressure because of the elevation of land. We deduce the total mass of the atmosphere ma: (2.2) where R = 6400 km is the radius of the Earth. The total number of moles of air in the atmosphere is Na = ma/Ma = 1.8x10 20 moles. Exercise 2-1.
The air density at sea level does not vary much around the world; the sea-level pressure varies by at most 5%, and the temperature rarely departs by more than 15% from 273 K, so that na remains within 25% of the value calculated here. The number density of CO2 is derived from the mixing ratio CCO2 = 365 ppmv: M a = C N2M N2 ++C O2M O2 C ArM Ar
4 kwi 2020 · In this equation, p ( h) is the atmospheric pressure at altitude h, p0 is the atmospheric pressure at sea level, g is the gravitational acceleration, ρ0 is the mass density of air at sea level, R is the gas constant, T is the temperature, M is the (average) molar mass, m is the average mass of a gas molecule, and H is a composite parameter somet...
Atmospheric pressure is slightly dependent on weather conditions. On the graph below, we can see the decrease in atmospheric pressure as the altitude increases. At sea level, the atmospheric pressure would be a little over \(100 \: \text{kPa}\) (one atmosphere or \(760 \: \text{mm} \: \ce{Hg}\)).
•Normal atmospheric pressure at sea level is referred to as standard pressure. •It is equal to –1.00 atm –760 torr (760 mm Hg) –101.325 kPa
The pressure exerted by Earth’s atmosphere, called barometric pressure, is about 101 kPa or 14.7 lb/in. 2 at sea level. barometric pressure can be measured with a barometer, a closed, inverted tube filled with mercury.
Surface Pressure vs. Sea Level Pressure • Sea Level Pressure – the pressure that would exist if the observation point were at sea level. • Surface Pressure – the pressure observed at a particular location ATMO 1300 Equation of State • Ideal gas law – P = pressure (Pa) – ρ= density (kg/m3) – T = temperature (K)
