Pressure variation in the environment illustrates how pressure varies with verti

Question

Pressure variation in the environment illustrates how pressure varies with vertical elevation due to the force required to support the weight of the fluid column above. For a liquid region of moderate depth the fluid density (rho) and gravitational acceleration (g) are constant. So the pressure difference (dp) for each unit change in elevation (dz) is constant (dp/dz = - rho g = constant). However in Earth's atmosphere (with elevation changes of many kilometers) the air density is not constant (and g may change a small amount). Hence the pressure difference (dp) for each unit change in elevation (dz) varies with elevation (dp/dz = - rho g = function of z). A rough first estimate for the pressure distribution in the standard atmosphere is obtained based on simplifications of assuming the temperature is constant and the gravitational acceleration is constant. Comment: When executed with small layer thickness the Euler approximation will match the integral. But variable tempe

Explanation / Answer

Atmospheric pressure also depends on the humidity and changes as weather changes.NASA has developed a relation to compute pressure at all locations on the earth at all times of the year.

p = po (1 - Lh/To)gM / RoL

Where,

p0 sea level standard atmospheric pressure 101325 Pa L temperature lapse rate, = g/cp for dry air 0.0065 K/m T0 sea level standard temperature 288.15 K g Earth-surface gravitational acceleration 9.80665 m/s2 M molar mass of dry air 0.0289644 kg/mol R0 universal gas constant 8.31447 J/(mol•K)

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