API field
Relative humidity
Optional; lets the model estimate precipitable water
Unit %
What it is
The relative humidity per interval, in percent. It is optional. The spectral correction needs the amount of water vapour in the atmosphere; when precipitable water is not given, the model estimates it from the humidity and the temperature.
Typical values and how to get it
Include it when the file has it. NSRDB and PVGIS files carry it. If not given: no humidity. The Lee and Panchula spectral correction then needs a precipitable water column and is skipped without one; the snow model then needs the Site tab's monthly humidity; a DIRINT upload uses its table's column for unknown precipitable water.
References
- Gueymard 1994, Analysis of monthly average atmospheric precipitable water and turbidity in Canada and northern United States, Solar Energy 53(1) 57–71
API
weather.relative_humidity