pvlib.atmosphere.get_relative_airmass

pvlib.atmosphere.get_relative_airmass(zenith, model='kastenyoung1989')

Calculate relative (not pressure-adjusted) airmass at sea level.

Parameter model allows selection of different airmass models.

Parameters:

• zenith (numeric) – Zenith angle of the sun. [degrees]

• model (string, default 'kastenyoung1989') –

  Available models include the following:

  • ’simple’ - secant(apparent zenith angle) - Note that this gives -Inf at zenith=90

  • ’kasten1966’ - See reference [1] - requires apparent sun zenith

  • ’youngirvine1967’ - See reference [2] - requires true sun zenith

  • ’kastenyoung1989’ (default) - See reference [3] - requires apparent sun zenith

  • ’gueymard1993’ - See reference [4] - requires apparent sun zenith

  • ’young1994’ - See reference [5] - requires true sun zenith

  • ’pickering2002’ - See reference [6] - requires apparent sun zenith

  • ’gueymard2003’ - See references [7] and [8] - requires apparent sun zenith

Returns:

airmass_relative (numeric) – Relative airmass at sea level. Returns NaN values for any zenith angle greater than 90 degrees. [unitless]

Notes

Some models use apparent (refraction-adjusted) zenith angle while other models use true (not refraction-adjusted) zenith angle. Apparent zenith angles should be calculated at sea level.

References

[1]

Fritz Kasten. “A New Table and Approximation Formula for the Relative Optical Air Mass”. Technical Report 136, Hanover, N.H.: U.S. Army Material Command, CRREL.

[2]

A. T. Young and W. M. Irvine, “Multicolor Photoelectric Photometry of the Brighter Planets,” The Astronomical Journal, vol. 72, pp. 945-950, 1967.

[3]

Fritz Kasten and Andrew Young. “Revised optical air mass tables and approximation formula”. Applied Optics 28:4735-4738

[4]

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.

[5]

A. T. Young, “AIR-MASS AND REFRACTION,” Applied Optics, vol. 33, pp. 1108-1110, Feb 1994.

[6]

Keith A. Pickering. “The Ancient Star Catalog”. DIO 12:1, 20,

[7]

C. Gueymard, “Direct solar transmittance and irradiance predictions with broadband models. Part I: detailed theoretical performance assessment”. Solar Energy, vol 74, pp. 355-379, 2003. DOI: 10.1016/S0038-092X(03)00195-6

[8]

C. Gueymard (2019). Clear-Sky Radiation Models and Aerosol Effects. In: Polo, J., Martín-Pomares, L., Sanfilippo, A. (eds) Solar Resources Mapping. Green Energy and Technology. Springer, Cham. DOI: 10.1007/978-3-319-97484-2_5

[9]

Matthew J. Reno, Clifford W. Hansen and Joshua S. Stein, “Global Horizontal Irradiance Clear Sky Models: Implementation and Analysis” Sandia Report, (2012).

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