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Unit conversion help

Tsonko Tsonev ttsonev at obzor.bio21.acad.bg
Sun Aug 24 13:29:32 EST 1997

In article <33F88EFA.8DB3A67E at mail.telepac.pt>, Monica Moura
<mtmoura at mail.telepac.pt> wrote:

> Please forgive me if this is too basic (or off topic) to post here, but
> I wonder if anyone could please help me with this conversion problem I
> have. How can I convert a value that is in lux (illuminance) to
> micromole*m^-2*sec^-1?
> Thanks in advance for your help,
> Best regards,
> Monica

Hi Monika,
Dr. Meunier is right writing "It depends on the spectrum of the source.
If I remember correctly, lux is relative to the human eye's sensitivity,
so conversions are approximative."

You can use the following conversion table suggested by LI-COR
(http://www.licor.com) and published also by Enoch & Kimball, eds.

Conversion factors for converting 400 to 700 nm photometric values in
klux to 400 to 700 nm photosynthetic photon flux density (PPFD) in

Light source
daylight		1 klux=18 micromole*m^-2*sec^-1
metal halide		1 klux=14 micromole*m^-2*sec^-1
sodium (HP)		1 klux=14 micromole*m^-2*sec^-1
mercury			1 klux=14 micromole*m^-2*sec^-1
white fluorescent	1 klux=12 micromole*m^-2*sec^-1
incandescent		1 klux=20 micromole*m^-2*sec^-1

LI-COR, Radiation Measurement and Instrumentation, LI-COR, Inc.,
Lincoln, Nebraska, 1982, 49 pp.
Enoch H.Z., B.A.Kimball (eds.) Carbon Dioxide Enrichment of Greenhouse
Crops, vol. I CRC Press, Boca Raton, Florida, 1986, 182 pp.(here are
also other useful conversion tables)

Best regards,
Tsonko Tsonev, Ph.D.
Institute of Plant Physiology, Bulgarian Academy of Sciences
Acad. G.Bonchev Str., Bl.21, BG-1113 Sofia, Bulgaria
Phone 359-2-713-2683, Fax 359-2-70-99-53
E-mail: ttsonev at obzor.bio21.acad.bg
Take a look at our Web page for announcement
of the 11-th Congress of the FESPP:
mirror site  http://www.bulgaria.com/fespp98/fespp98.html

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