Reptile Lamp Database

Spectrum 4: SUN Edit
Delete

Full Spectrum

solar spectrum
Melbourne, Victoria, Australia 37° 49'
17th Jan 1990, at solar noon
solar altitude 73.0°

from: B.L. Diffey / Methods 28 (2002) 4–13

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 9/Nov/2009 ; updated: Sarina Wunderlich 9/Oct/2011

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 - 400 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 ( 0.17 ; 0.0049 ) ( 0.0002 ; 0.034 ) ( 1.3E-5 ; 0.0002 ; 0.034 )
CCT 0 Kelvin 0 Kelvin 0 Kelvin
distance 0 0
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) 5980 µW/cm² = 59.8 W/m²
UVA (US) ( 320 nm - 400 nm) 5810 µW/cm² = 58.1 W/m²
UVB (EU) ( 280 nm - 315 nm) 197 µW/cm² = 1.97 W/m²
UVB (US) ( 280 nm - 320 nm) 360 µW/cm² = 3.6 W/m²
UVC ( 0 nm - 280 nm) 0 µW/cm² = 0 W/m²
vis. UVA ( 350 nm - 380 nm) 2390 µW/cm² = 23.9 W/m²
purple ( 380 nm - 420 nm) 1640 µW/cm² = 16.4 W/m²
blue ( 420 nm - 490 nm) 0 µW/cm² = 0 W/m²
green ( 490 nm - 575 nm) 0 µW/cm² = 0 W/m²
yellow ( 575 nm - 585 nm) 0 µW/cm² = 0 W/m²
orange ( 585 nm - 650 nm) 0 µW/cm² = 0 W/m²
red ( 650 nm - 780 nm) 0 µW/cm² = 0 W/m²
VIS ( 380 nm - 780 nm) 1640 µW/cm² = 16.4 W/m²
PAR ( 400 nm - 700 nm) 0 µW/cm² = 0 W/m²
total ( 0 nm - 0 nm) 6170 µW/cm² = 61.7 W/m²
UVA1 ( 315 nm - 350 nm) 1950 µW/cm² = 19.5 W/m²
VIS Rep3 ( 350 nm - 600 nm) 4030 µW/cm² = 40.3 W/m²
VIS Rep4 ( 350 nm - 700 nm) 4030 µW/cm² = 40.3 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 11.1 UV-Index
Pyrimidine dimerization of DNA 140 µW/cm²
Photoceratitis 15.7 µW/cm²
Photoconjunctivitis 0.191 µW/cm²
DNA Damage 0.648
Vitamin D3 47.7 µW/cm²
Photosynthesis 0 µW/cm²
Luminosity 5.58 lx
Human L-Cone 0.809 µW/cm²
Human M-Cone 0.742 µW/cm²
Human S-Cone 18.5 µW/cm²
CIE X 8.63 µW/cm²
CIE Y 0.245 µW/cm²
CIE Z 40.8 µW/cm²
PAR 0 mol photons
Extinction preD3 0.389 m²/mol
Extinction Tachysterol 1.42 m²/mol
Extinction Lumisterol 0.0332 m²/mol
Extinction 7DHC 0.0198 m²/mol
L-Cone 0.0833 µW/cm²
M-Cone 1.3 µW/cm²
S-Cone 220 µW/cm²
U-Cone 6300 µW/cm²
UVR - ICNIRP 2004 7.18 Rel Biol Eff
Melatonin Supression 0 µW/cm²
Blue Light Hazard 95 µW/cm² (17000 µW/cm² per 1000 lx)
CIE 174:2006 PreVit D3 52.8 µW/cm²
Lumen Reptil 8980 "pseudo-lx"
Vitamin D3 Degradation 75 µW/cm²
Broadbandmeters
Solarmeter 6.2 (UVB, pre 2010) 502 µW/cm²
Solarmeter 6.5 (UV-Index, pre 2010) 14.4
Leybold UVB 339 µW/cm²
Leybold UVA 3100 µW/cm²
Leybold UVC 0.00357 µW/cm²
DeltaOhm UVB 1110 µW/cm²
DeltaOhm UVC 110 µW/cm²
Vernier UVB 111 µW/cm²
Vernier UVA 2770 µW/cm²
Gröbel UVA 3550 µW/cm²
Gröbel UVB 157 µW/cm²
Gröbel UVC -0.0874 µW/cm²
Solarmeter 6.4 (D3) 45.1 IU/min
UVX-31 1300 µW/cm²
IL UVB 0.234 µW/cm²
IL UVA 3620 µW/cm²
Solarmeter 6.5 (UVI, post 2010) 12.5 UV-Index
Solarmeter 6.2 (UVB, post 2010) 361 µW/cm² (Solarmeter Ratio = 28.9)
Solarmeter AlGaN 6.5 UVI sensor 180 UV Index
GenUV 7.1 UV-Index 11.2 UV-Index
Solarmeter 10.0 (Global Power) 28 W/m²
Solarmeter 4.0 (UVA) 55.4 mW/cm²