pvlib.atmosphere.relativeairmass¶
-
pvlib.atmosphere.
relativeairmass
(zenith, model='kastenyoung1989')[source]¶ Gives the relative (not pressure-corrected) airmass.
Gives the airmass at sea-level when given a sun zenith angle (in degrees). The
model
variable allows selection of different airmass models (described below). Ifmodel
is not included or is not valid, the default model is ‘kastenyoung1989’.Parameters: - zenith : numeric
Zenith angle of the sun in degrees. Note that some models use the apparent (refraction corrected) zenith angle, and some models use the true (not refraction-corrected) zenith angle. See model descriptions to determine which type of zenith angle is required. Apparent zenith angles must be calculated at sea level.
- 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’ - See reference [3] - requires apparent sun zenith
- ‘gueymard1993’ - See reference [4] - requires apparent sun zenith
- ‘young1994’ - See reference [5] - requries true sun zenith
- ‘pickering2002’ - See reference [6] - requires apparent sun zenith
Returns: - airmass_relative : numeric
Relative airmass at sea level. Will return NaN values for any zenith angle greater than 90 degrees.
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] Matthew J. Reno, Clifford W. Hansen and Joshua S. Stein, “Global Horizontal Irradiance Clear Sky Models: Implementation and Analysis” Sandia Report, (2012).