List of abbreviations and symbols

For quantities and units used in photobiology we follow, as much as possible, the recommendations of the Commission Internationale de l’Éclairage as described by Sliney (2007).

Definition
absorptance (%).
water vapour pressure difference (Pa).
emittance ().
\(\lambda\) wavelength (nm).
solar zenith angle (degrees).
\(\nu\) frequency (Hz or s\(^{-1}\)).
reflectance (%).
\(\sigma\) Stefan-Boltzmann constant.
transmittance (%).
\(\chi\) water vapour content in the air ().
absorbance (absorbance units).
ANCOVA analysis of covariance.
ANOVA analysis of variance.
BSWF BSWF.
\(c\) speed of light in a vacuum.
CCD charge coupled device, a type of light detector.
CDOM coloured dissolved organic matter.
CFC chlorofluorocarbons.
c.i. confidence interval.
CIE Commission Internationale de l’Éclairage (International Commission on Illumination);
or when refering to an action spectrum, the erythemal action spectrum standardized by CIE.
CTC closed-top chamber.
DAD diode array detector, a type of light detector based on photodiodes.
DBP dibutylphthalate.
DC direct current.
DIBP diisobutylphthalate.
DNA(N) action spectrum for ‘naked’ DNA.
DNA(P) action spectrum for DNA in plants.
DOM dissolved organic matter.
DU Dobson units.
\(e\) water vapour partial pressure (Pa).
(energy) irradiance ().
spectral (energy) irradiance ().
fluence rate, also called scalar irradiance ().
ESR early stage researcher.
FACE free air carbon-dioxide enhancement.
FEL a certain type of 1000 W incandescent lamp.
FLAV action spectrum for accumulation of flavonoids.
FWHM full-width half-maximum.
GAW Global Atmosphere Watch.
GEN generalized plant action spectrum, also abreviated as GPAS (Caldwell 1971).
GEN(G) mathematical formulation of GEN by Green, Sawada, and Shettle (1974) .
GEN(T) mathematical formulation of GEN by Thimijan, Carns, and Campbell (1978).
\(h\) Planck’s constant.
\(h^\prime\) Planck’s constant per mole of photons.
exposure, frequently called dose by biologists ().
biologically effective (energy) exposure ().
biologically effective photon exposure ().
HPS high pressure sodium, a type of discharge lamp.
HSD honestly signifcant difference.
\(k_\mathrm{B}\) Boltzmann constant.
radiance ().
LAI leaf area index, the ratio of projected leaf area to the ground area.
LED light emitting diode.
LME linear mixed effects (type of statistical model).
LSD least significant difference.
\(n\) number of replicates (number of experimental units per treatment).
\(N\) total number of experimental units in an experiment.
\(N_\mathrm{A}\) Avogadro constant (also called Avogadro’s number).
NIST National Institute of Standards and Technology (U.S.A.).
NLME non-linear mixed effects (statistical model).
OTC open-top chamber.
PAR, 400–700 nm.
measured as energy or photon irradiance.
PC polycarbonate, a plastic.
PG action spectrum for plant growth.
PHIN action spectrum for photoinhibition of isolated chloroplasts.
PID PID (control algorithm).
PMMA polymethylmethacrylate.
PPFD, another name for
photon irradiance ().
PTFE polytetrafluoroethylene.
PVC polyvinylchloride.
\(q\) energy in one photon (‘energy of light’).
\(q^\prime\) energy in one mole of photons.
photon irradiance ().
spectral photon irradiance ().
r\(_0\) distance from sun to earth.
RAF (nondimensional).
RH relative humidity (%).
energy effectiveness (relative units).
spectral energy effectiveness (relative units).
quantum effectiveness (relative units).
spectral quantum effectiveness (relative units).
s.d. standard deviation.
SDK software development kit.
s.e. standard error of the mean.
SR spectroradiometer.
\(t\) time.
\(T\) temperature.
TUV tropospheric .
electric potential difference or voltage (e.g. sensor output in V).
ultraviolet radiation (\(\lambda =\) 100–400 nm).
ultraviolet-A radiation (\(\lambda =\) 315–400 nm).
ultraviolet-B radiation (\(\lambda =\) 280–315 nm).
ultraviolet-C radiation (\(\lambda =\) 100–280 nm).
biologically effective radiation.
UTC coordinated universal time, replaces GMT in technical use.
VIS radiation visible to the human eye (\(\approx\) 400–700 nm).
WMO World Meteorological Organization.
VPD water vapour pressure deficit (Pa).
WOUDC World Ozone and Ultraviolet Radiation Data Centre.

Caldwell, M. M. 1971. “Solar UV Irradiation and the Growth and Development of Higher Plants.” In Photophysiology, edited by A. C. Giese, 6:131–77. New York: Academic Press.

Green, A. E. S., T. Sawada, and E. P. Shettle. 1974. “The Middle Ultraviolet Reaching the Ground.” Photochemistry and Photobiology 19: 251–59. https://doi.org/10.1111/j.1751-1097.1974.tb06508.x.

Sliney, David H. 2007. “Radiometric Quantities and Units Used in Photobiology and Photochemistry: Recommendations of the Commission Internationale de L’Eclairage (International Commission on Illumination).” Photochemistry and Photobiology 83: 425–32. https://doi.org/10.1562/2006-11-14-RA-1081.

Thimijan, R W, H R Carns, and L E Campbell. 1978. “Final Report (EPA-IAG-D6-0168): Radiation Sources and Related Environmental Control for Biological and Climatic Effects UV Research (BACER).” Edited by R J McCracken. Washington, DC: Environmental Protection Agency.