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Unformatted text preview: The Standard Atmosphere The Standard Atmosphere The Standard Atmosphere Some definitions Some definitions Construction of the standard atmosphere – Variation of p , T and ρ with altitude Construction of the standard atmosphere – Variation of p , T and ρ with altitude Absolute altitude Geometric altitude Geopotential altitude Absolute altitude Geometric altitude Geopotential altitude Some physics – The hydrostatic equation Some physics – The hydrostatic equation Definitions of pressure, density, and temperature altitudes Definitions of pressure, density, and temperature altitudes Mysterious FishyLooking Thingy Tourist Transportation? Upside down? The Standard Atmosphere The Standard Atmosphere The Standard Atmosphere Some definitions Some definitions Construction of the standard atmosphere – Variation of p , T and ρ with altitude Construction of the standard atmosphere – Variation of p , T and ρ with altitude Absolute altitude Geometric altitude Geopotential altitude Absolute altitude Geometric altitude Geopotential altitude Some physics – The hydrostatic equation Some physics – The hydrostatic equation Definitions of pressure, density, and temperature altitudes Definitions of pressure, density, and temperature altitudes Altitude (Six Different Flavors) • Geometric altitude h G : altitude measured from sea level • Absolute altitude h a : altitude measured from center of the earth h a = h G + r , where r is the radius of the earth • Local acceleration due to gravity depends on altitude g = g (r/h a ) 2 = g 0 (r/[r+h G ]) 2 This variation has an effect on the pressure • Geometric altitude h G : altitude measured from sea level • Absolute altitude h a : altitude measured from center of the earth h a = h G + r , where r is the radius of the earth • Local acceleration due to gravity depends on altitude g = g (r/h a ) 2 = g 0 (r/[r+h G ]) 2 This variation has an effect on the pressure Hydrostatic Equation • Compute the balance of forces acting on an element of fluid at rest. • The element of fluid has unit width in both horizontal directions and height dh G in the vertical direction • Newton’s law: sum of forces = zero p = p + dp + ρ g dh G dp =  ρ g dh G • The hydrostatic equation applies to any fluid of density ρ • The H.E. is a differential equation: p , ρ , and g depend on h G • First step: assume g = g • Compute the balance of forces acting on an element of fluid at rest. • The element of fluid has unit width in both horizontal directions and height dh G in the vertical direction • Newton’s law: sum of forces = zero p = p + dp + ρ g dh G dp =  ρ g dh G • The hydrostatic equation applies to any fluid of density ρ • The H.E. is a differential equation: p , ρ , and g depend on h G • First step: assume g = g dh G Increasing altitude p+dp p ρ (1)(1)dh G g Integrating the Hydrostatic Eq....
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 Spring '08
 Staff
 Thermodynamics, Atmospheric thermodynamics, geopotential altitude

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