pvlib.irradiance.liujordan(zenith, transmittance, airmass, dni_extra=1367.0)[source]

Determine DNI, DHI, GHI from extraterrestrial flux, transmittance, and optical air mass number.

Liu and Jordan, 1960, developed a simplified direct radiation model. DHI is from an empirical equation for diffuse radiation from Liu and Jordan, 1960.

  • zenith (pd.Series) – True (not refraction-corrected) zenith angles in decimal degrees. If Z is a vector it must be of the same size as all other vector inputs. Z must be >=0 and <=180.

  • transmittance (float) – Atmospheric transmittance between 0 and 1.

  • pressure (float, default 101325.0) – Air pressure

  • dni_extra (float, default 1367.0) – Direct irradiance incident at the top of the atmosphere.


irradiance (DataFrame) – Modeled direct normal irradiance, direct horizontal irradiance, and global horizontal irradiance in W/m^2


[1] Campbell, G. S., J. M. Norman (1998) An Introduction to Environmental Biophysics. 2nd Ed. New York: Springer.

[2] Liu, B. Y., R. C. Jordan, (1960). “The interrelationship and characteristic distribution of direct, diffuse, and total solar radiation”. Solar Energy 4:1-19