air_densitydocumentation
air_densitycomputes density from the baromometric forumula for a US Standard Atmosphere.
See alsoair_pressure.
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Contents
Syntax
rho = air_density(h)
Description
rho = air_density(h)returns the atmospheric densityrhoin kg/m^3 corresponding to the heightshin geometric meters above sea level.
Example
The US Standard Atmosphere formula is valid to 86 km above sea level, so let's look at air density from sea level to 85 km:
h = 0:85e3; rho = air_density(h); figure plot(rho,h/1000) axistightboxoffylabel'height above sea level (km)'xlabel'density (kg m^{-3})'
The formula uses a piecewise function that calculates an equation based on different constants for different layers of the atmosphere. The bases of those layers are at 0, 11, 20, 32, 47, 51, and 71 km above sea level. For context, we can plot those layer bases as horizontal lines usinghline:
LayerBases = [0 11 20 32 47 51 71]; hline(LayerBases,':','color',rgb('gray'))
Pro tip: For some applictions it may be helpful to display the x axis on a log scale. To do that, we could have plotted the data withsemilogxinstead of using theplotfunction above, or we can change the x scale to log like this:
set(gca,'xscale','log')
好奇的大气层之间的关系spheric density and atmospheric pressure? Compare withair_pressure:
p = air_pressure(h); figure plot(p/1000,rho) axistightboxoffxlabel'pressure (kPa)'ylabel'density (kg m^{-3})'
Author Info
This function is part of theClimate Data Toolbox for Matlab. The function and supporting documentation were written by Chad A. Greene of the University of Texas at Austin.