Duration of Vitamin D Synthesis in Human Skin

Alternative services: http://nadir.nilu.no/~olaeng/fastrt/VitD.html and http://zardoz.nilu.no/~olaeng/fastrt/VitD.html

Version 1.0, Copyright © 2005 Ola Engelsen
Norwegian Institute for Air Research, Email: ola.engelsen@nilu.no

Press here for more information on VitD and simpler versions


Solar Geometry for Irradiance Calculations

Month Day

Latitude (degs N) Longitude (degs E)

When checked, use degrees for Solar Zenith Angle directly and ignore Date, Time, and Location


Cloudless sky: Visibility of km, Range [5-350] km. Ångström β of , Range [0.0-0.4] (AOD = βλ-1.3).

Scattered clouds: Cloud fraction of %, Range [0-100]. Cloud liquid water column of g m-2, Range [0-5000].
Press here for total cloud fractions from the NOAA AVHRR Pathfinder products.

Broken clouds (radiation enhancement): Cloud liquid water column of g m-2, Range [0-5000].

Overcast sky: Cloud liquid water column of g m-2, Range [0-5000]. (= cloud optical depth @ 360 nm * 5000/1083)


Total ozone column: Dobson Units (1000 * cm atm), Range [100-600]
Press here for total ozone column measurements from the TOMS satellite instruments.


Surface altitude km. Range [0.0-6.0] km

Surface albedo of Range [0.0-1.0].

Surface type:



This work has been funded by the European Commission (EC) and the Norwegian Research Council ( NFR) through the projects UV Radiation in the Arctic: Past, Present and Future (UVRAPPF) and European Database for UV Climatology and Evaluation (EDUCE).


Ola Engelsen                                                                          NILU Phone: (+47) 77 75 03 75
Norwegian Institute for Air Research (NILU)                    NILU Fax no:(+47) 77 75 0376
N-9296 Tromsø                                                                     Office-Phone no:(+47) 77 75 03 89
Norway                                                                                  Email: ola.engelsen@nilu.no