def get_absolute_airmass(airmass_relative, pressure=<NUM_LIT>):
airmass_absolute = airmass_relative * pressure / <NUM_LIT><EOL>return airmass_absolute<EOL>
Determine absolute (pressure corrected) airmass from relative
airmass and pressure

Gives the airmass for locations not at sea-level (i.e. not at
standard pressure). The input argument "AMrelative" is the relative
airmass. The input argument "pressure" is the pressure (in Pascals)
at the location of interest and must be greater than 0. The
calculation for absolute airmass is

.. math::
    absolute airmass = (relative airmass)*pressure/101325

Parameters
----------
airmass_relative : numeric
    The airmass at sea-level.

pressure : numeric, default 101325
    The site pressure in Pascal.

Returns
-------
airmass_absolute : numeric
    Absolute (pressure corrected) airmass

References
----------
[1] C. Gueymard, "Critical analysis and performance assessment of
clear sky solar irradiance models using theoretical and measured
data," Solar Energy, vol. 51, pp. 121-138, 1993.