Illuminance turbidity factor Til--Algorithm 1.21
The illuminance
at the earth's surface from the solar beam depends on attenuation in the
atmosphere; an index of this attenuation is the illuminance turbidity factor.
The corresponding index of attenuation for total radiation is the Linke
turbidity factor. More extensive data are available for Linke turbidity than
illuminance turbidity, and this algorithm is an empirical conversimula.
- Input
- Linke turbidity factor, TL
- Equation
- This equation gives the relationship between illuminance turbidity and
Linke turbidity under European clear skies
- Source
- Page(2)
- Note
- Typical values of Til under cloudless skies are given in the
following table:
| region |
Til |
| perfectly dry clean air |
1.0 |
| dry mountain areas |
1.5 |
| rural areas |
2.5 |
| urban areas |
3.0 |
| industrial areas |
5.0 |
References
- Page J K and Sharples S The SERC meteorological data base Volume II:
algorithm manual 2nd Edition Department of Building Science University of
Sheffield (1988)
- Page J K and Thompson J L Modelling daylight availability National
Lighting Conference Warwick 1982 Chartered Institution of Building Services
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