airmass_from_elevation

pycraf.atm.airmass_from_elevation(elev)

Airmass derived from elevation using extrapolation by Maddalena & Johnson.

Parameters:

elevQuantity

Elevation [deg]

Returns:

airmassQuantity

Airmass [dimless]

Notes

For low elevations, the well-known 1/sin-law breaks down. Maddalena & Johnson (2006) propose the following extrapolation for El < 32 deg:

\[\begin{split}\textrm{AM} = \begin{cases} -0.02344 + \frac{1.0140}{ \sin\left(\mathrm{El} + \frac{5.18}{\mathrm{El} + 3.35}\right)}\qquad\mathrm{for~}\mathrm{El}<32\\ \frac{1}{\sin\mathrm{El}}\qquad\mathrm{for~}\mathrm{El}\geq32 \end{cases}\end{split}\]