# pvlib.atmosphere.get_absolute_airmass¶

pvlib.atmosphere.get_absolute_airmass(airmass_relative, pressure=101325.0)[source]

Determine absolute (pressure-adjusted) airmass from relative airmass and pressure.

The calculation for absolute airmass ($$AM_a$$) is

$AM_a = AM_r \frac{P}{101325}$

where $$AM_r$$ is relative air mass at sea level and $$P$$ is atmospheric pressure.

Parameters
• airmass_relative (numeric) – The airmass at sea level. [unitless]

• pressure (numeric, default 101325) – Atmospheric pressure. [Pa]

Returns

airmass_absolute (numeric) – Absolute (pressure-adjusted) 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.