Atmosphere Lecture 2 ME EN 415 Andrew Ning aning@byu.edu UCAR - - PowerPoint PPT Presentation

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Atmosphere Lecture 2 ME EN 415 Andrew Ning aning@byu.edu UCAR - - PowerPoint PPT Presentation

Sep 11, 2023 236 likes •393 views

Atmosphere Lecture 2 ME EN 415 Andrew Ning aning@byu.edu UCAR Altitude Geometric Altitude: Absolute Altitude: Pressure Altitude: Geopotential Altitude: Altimeters International Standard Atmosphere Geopotential Temperature Altitude

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ME EN 415 Andrew Ning aning@byu.edu

Atmosphere

Lecture 2

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UCAR

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Altitude

Geometric Altitude: Absolute Altitude: Geopotential Altitude: Pressure Altitude:

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Altimeters

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International Standard Atmosphere

Geopotential Altitude (km) Temperature Gradient (K/km)

  • 6.5

11 0.0 20 +1.0 32 +2.8 47 0.0 51

  • 2.8

71

  • 2.0

84.8520

Temperature Altitude

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Sea Level Properties TSL 288.15 K PSL 1.01325 × 105 Pa µSL 1.79 × 10−5 kg/m-s g 9.80665 m/s2

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Hydrostatics

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Isothermal Layers

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Gradient Layers

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Curve Fit

modified slightly from: Mark Drela, Flight Vehicle Aerodynamics

P(h) = PSL exp ✓ −0.118h − 0.0015h2 1 − 0.018h + 0.0011h2 ◆ applicable for altitudes below 47 km T(h) = TSL − 71.5 + 2.0 ln ⇥ 1 + exp(35.75 − 3.25h) + exp(−3.0 + 0.0003h3) ⇤ (h in km, T in K)

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Upper Atmosphere NRLMSISE-00

(up to 1000 km)

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Upper Atmosphere NRLMSISE-00

  • r for a simple approximation during atmospheric entry:

(reasonable up to 140 km)

P PSL = exp−

gh RTm

(up to 1000 km)

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Create Your Own

P, T, ρ = atmosphere(h)

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More Comprehensive Databases

https://earth.nullschool.net ERA Interim dataset