A study of zenith luminance on Madrid cloudless skies

✍ Scribed by A Soler; K.K Gopinathan

• Book ID: 104167412
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 781 KB
• Volume: 69
• Category: Article
• ISSN: 0038-092X
• DOI: 10.1016/s0038-092x(00)00084-0

✦ Synopsis

The zenith luminance (L ) has been measured for cloudless skies at the IDMP station in Madrid. z Mean values obtained at every 15 min have been fitted vs. solar elevation (a). A 5th degree polynomial connecting log (L ) against (a) gives the best correlation in terms of the correlation coefficient (r 5 0.9358). A z possible explanation of the dependence of the zenith luminance on solar elevation at low values is given.

Án exponential model obtained by other authors (Vazquez and Bernabeu, 1997) for a nearby temporary station in the same city does not account for the qualitative dependence of L vs. a for a , ¯158, and also z overestimates experimental values for high solar elevations.

The effect of turbidity on L is studied categorizing available data in three specified groups of T , the visual z v or luminous / illuminance turbidity. Best fits with 5th degree polynomials connecting log (L ) against (a) are z given for: T , 3, 3 , T , 5, and T . 5.