Air Mass

This function empirically computes the non-pressure-corrected (sea level) and pressure-corrected (at altitude) air
masses as a function of the solar zenith angle.

Inputs

AirMass Inputs

Outputs

 

 

Algorithm (Bird & Hulstrom Version)

Compute the sea-level air mass:

AirMass Bird Hulstrom Algo2
 

Algorithm (Kasten / Sandia Version)

Compute the sea-level air mass:

AirMass Kasten Sandia Algo3
 

Algorithm (Common Pressure Correction and Filtering)

1.) Restrict the calculation of the air mass for zenith angles less than 89°

AirMass Pressure Correction Algo4
2.) Reduce the air mass function by the actual pressure (a function of elevation or an input given in the weather
data):

AirMass Pressure Correction Algo5

Reference

Bird, R., Hulstrom, R., A Simplified Clear Sky Model for Direct and Diffuse Insolation on Horizontal Surfaces, 1981
NREL SERI/TP-642-761

Kasten, F. Discussions on the Relative Air Mass, Light Research Technology 25, 129.