Reptile Lamp Database

Spectrum 21: SUN Edit
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Full Spectrum

Global Spectral Irradiance
11. January 1996, Australia
solar altitude 85°

from: Bernhard, G., B. Mayer, G. Seckmeyer, and A. Moise (1997), Measurements of spectral solar UV irradiance in tropical Australia, J. Geophys. Res., 102(D7), 8719–8730

Measurement

Brand other
other
Lamp Product Sun
Direct sunlight
Lamp ID SUN (01/2000)
Spectrometer -
Ballast - no ballast or default/unknown ballast -
Reflector
Distance 0 cm
Age 0 hours
Originator (measurement) Publication
Database entry created: Sarina Wunderlich 12/Nov/2009 ; updated: Sarina Wunderlich 25/Oct/2016

Colorimetry

Colorimetry is the science to describe physically the human color perception. The wavelength range 380 nm - 780 nm is visible to humans and detected by three different photoreceptors. Many Reptiles see the range 350 nm - 800 nm and have an additional UV photoreceptor in their retina.

WARNING: The measurement range (350 - 800 nm) is not sufficient for this evaluation! Data is only available in the range 290 - 650 nm. Results are shown anyway but should be ignored by anyone except experts.

Spectrum in the visible wavelength range

Whereas a spectrometer measures the intensity in every tiny wavelength interval resulting in thousands of individual intensities, the human eye only measures three intensities detected by the three cones. The same is true for the reptile eye with usually three or four photoreceptors. Effectively the detailled spectrum displayed above reduces to a much compacter bar graph displayed below. The photoreceptor sensitivites from these L-Cone, M-Cone, S-Cone, and U-Cone are used, they are chosen as an average of measured reptile photoreceptor sensitivity curves. The bar graph also shows as reference the intensity seen by the three or four photoreceptors for average sunlight (id 1).

From these three numbers the colour coordinate and the correlated colour temperature for humans are calculated using the CIE standard method. I adapted this concept to a "3 cone reptile (M,S,U)" and a "4 cone reptile (L,M,S,U)". I am sure, that this adaption to other colour spaces makes sense mathematically and this is also done in scientific research regarding colour vision of animals, however I have not seen calculation of colour temperatures for other animals in the scientific literature. Even if it is hypothetical, at least this shows, how arbitrary the colour temperature is, and that the colour temperature calculated for humans does not apply to reptiles. The colour spaces also show the colour coordinates of different phases of daylight ((ids 1, 338451, 511513 ), indicated by crosses, coloured in the appriximate colour perceived by a human.

Human (CIE) 3 cone reptile 4 cone reptile
Cone Excitation
Colour Coordinate ( 0.31 ; 0.34 ) ( 0.4 ; 0.37 ) ( 0.26 ; 0.3 ; 0.27 )
CCT 6300 Kelvin 4900 Kelvin 5500 Kelvin
distance 0.029 0.034
colour space 3-D-graph not implemented yet

Vitamin D3 Analysis

Vitamin D3 is produced by UVB radiation around 300 nm. 7DHC/ProD3 present in the skin is converted to PreD3 when absorbing an UV photon. PreD3 can be converted back to ProD3, to Lumisterol, or to Tachysterol when absorbing another UV photon or can be converted to Vitamin D3 in a warm environment.

This process prevents any overdose of vitamin D3 from UV radiation with a spectrum similar to sunlight. As a comparison the solar spectra at 20°(id:14) and at 85°(id:21) solar angle are shown.

Spectrum in the vitamin D3 active wavelength range

The equilibrium of the photoproducts depends on the actual UV spectrum in the range 250 nm - 340 nm. With knowledge of the conversion probabilities and absorption spectra of 7DHC, PreD3, Tachysterol, and Lumisterol it is possible to calculate the ratio of photoproducts in equilibrium. This is based on scientific literature [1066], however the constants that are used for the calculation are not well calibrated with experiments. It is therefore not a solid method, but I consider it useful as a first guess how natural a UV spectrum is.

Caveat: This evaluation is extremely sensitive to the qualitiy of the spectral measurement in the range 220 nm - 340 nm. High quality spectrometers and good background calibration is needed to get the noise below 300 nm low enough for this evaluation. Please check at least the UV graph above for noise.

Simulation of the development of the Vitamin D3 photoproducts Simulation of the development of the Vitamin D3 photoproducts

The ratio of the two solarmeters 6.2 (UVB) and 6.5 (UV index) readings has proven a useful and very simply number to acess the spectral shape in the vitamin-d3-active region.

Effective Irradiances

Effective irradiances are calculated for all ranges, actionspectra and radiometers currently present in this database.

The calculation method is a numerical implementation (Simpson's rule) of the formula

To learn more about calculating effective irradiances and radiometers I recommend this excellent report on UVB meters: Characterizing the Performance of Integral Measuring UV-Meters (pdf).

The numbers in the following tables can also be used to estimate certain (effective) irradiances from radiomer readings. Example: If the database lists

  • range: UVB (US) = 13.8 µW/cm²
  • radiometer: Solarmeter 6.2 = 19.6 µW/cm²
then any Solarmeter 6.2 reading multiplied with 0.7 (0.7=13.8/19.6) is an estimate of UVB irradiance for this specific lamp. If you do so, always make sure, that the calculated (effective) irradiance is valid. The calculated value is not valid, if the lamp's spectrum is not measured in the relevant range.

Ranges
UVA (EU) ( 315 nm - 400 nm) 6860 µW/cm² = 68.6 W/m²
UVA (US) ( 320 nm - 400 nm) 6700 µW/cm² = 67 W/m²
UVB (EU) ( 280 nm - 315 nm) 282 µW/cm² = 2.82 W/m²
UVB (US) ( 280 nm - 320 nm) 440 µW/cm² = 4.4 W/m²
UVC ( 0 nm - 280 nm) 0 µW/cm² = 0 W/m²
vis. UVA ( 350 nm - 380 nm) 2690 µW/cm² = 26.9 W/m²
purple ( 380 nm - 420 nm) 5080 µW/cm² = 50.8 W/m²
blue ( 420 nm - 490 nm) 13000 µW/cm² = 130 W/m²
green ( 490 nm - 575 nm) 16600 µW/cm² = 166 W/m²
yellow ( 575 nm - 585 nm) 1750 µW/cm² = 17.5 W/m²
orange ( 585 nm - 650 nm) 9940 µW/cm² = 99.4 W/m²
red ( 650 nm - 780 nm) 0 µW/cm² = 0 W/m²
VIS ( 380 nm - 780 nm) 46400 µW/cm² = 464 W/m²
PAR ( 400 nm - 700 nm) 44500 µW/cm² = 445 W/m²
total ( 0 nm - 0 nm) 51600 µW/cm² = 516 W/m²
UVA1 ( 315 nm - 350 nm) 2200 µW/cm² = 22 W/m²
VIS Rep3 ( 350 nm - 600 nm) 40900 µW/cm² = 409 W/m²
VIS Rep4 ( 350 nm - 700 nm) 49100 µW/cm² = 491 W/m²
IRA ( 700 nm - 1400 nm) 0 µW/cm² = 0 W/m²
IRB ( 1400 nm - 3000 nm) 0 µW/cm² = 0 W/m²
Actionspectra
Erythema 14.7 UV-Index
Pyrimidine dimerization of DNA 178 µW/cm²
Photoceratitis 19.9 µW/cm²
Photoconjunctivitis 0.279 µW/cm²
DNA Damage 0.951
Vitamin D3 64.1 µW/cm²
Photosynthesis 30300 µW/cm²
Luminosity 136000 lx
Human L-Cone 20200 µW/cm²
Human M-Cone 17300 µW/cm²
Human S-Cone 10700 µW/cm²
CIE X 17700 µW/cm²
CIE Y 18900 µW/cm²
CIE Z 19700 µW/cm²
PAR 194000000 mol photons
Extinction preD3 0.485 m²/mol
Extinction Tachysterol 1.75 m²/mol
Extinction Lumisterol 0.0465 m²/mol
Extinction 7DHC 0.0306 m²/mol
L-Cone 16700 µW/cm²
M-Cone 19000 µW/cm²
S-Cone 17500 µW/cm²
U-Cone 10900 µW/cm²
UVR - ICNIRP 2004 9.97 Rel Biol Eff
Melatonin Supression 16200 µW/cm²
Blue Light Hazard 12100 µW/cm² (88.6 µW/cm² per 1000 lx)
CIE 174:2006 PreVit D3 70.6 µW/cm²
Lumen Reptil 147000 "pseudo-lx"
Vitamin D3 Degradation 91.8 µW/cm²
Broadbandmeters
Solarmeter 6.2 (UVB, pre 2010) 605 µW/cm²
Solarmeter 6.5 (UV-Index, pre 2010) 19.3
Leybold UVB 412 µW/cm²
Leybold UVA 3510 µW/cm²
Leybold UVC 0.00626 µW/cm²
DeltaOhm UVB 1300 µW/cm²
DeltaOhm UVC 122 µW/cm²
Vernier UVB 145 µW/cm²
Vernier UVA 3160 µW/cm²
Gröbel UVA 4050 µW/cm²
Gröbel UVB 197 µW/cm²
Gröbel UVC -0.1 µW/cm²
Solarmeter 6.4 (D3) 60.2 IU/min
UVX-31 1500 µW/cm²
IL UVB 0.281 µW/cm²
IL UVA 4120 µW/cm²
Solarmeter 6.5 (UVI, post 2010) 16.5 UV-Index
Solarmeter 6.2 (UVB, post 2010) 429 µW/cm² (Solarmeter Ratio = 26)
Solarmeter AlGaN 6.5 UVI sensor 227 UV Index
GenUV 7.1 UV-Index 13.8 UV-Index
Solarmeter 10.0 (Global Power) 471 W/m²
Solarmeter 4.0 (UVA) 67.3 mW/cm²