Què és la llum ultraviolada?
La llum forma part d'un espectre anomenat espectre electromagnètic, que també inclou raigs gamma, raigs-X, radiació ultraviolada i infraroja-, microones i ones de ràdio.
The Electromagnetic Spectrum is the way scientists refer to a stream of energy (photons). Photons move in waves. The gap between these waves is governed by how much energy the photon has. Big gaps (long waves) indicate lower energy and small gaps (short waves) indicate higher energy. To make it easier to understand, this stream of energy is split into groups according to the gap between the waves - the "wavelength".
Radio waves (long wavelength, low energy) can have as much as a kilometre between each wave whereas at the other end of the spectrum, with visible and ultraviolet light (short wavelength, high energy) the gap is so small it's measured in nm (nanometers – 1 thousand of a millionth of a metre!).
The human eye can see radiation with wavelengths from 400 to 700 nanometers (nm), and so we refer to this as "visible light". Ultraviolet light has a shorter wavelength than visible light, and cannot be seen by humans although for many animals, including reptiles, vision extends well into the ultraviolet.
Al diagrama següent podeu veure com la llum ultraviolada encaixa en l'espectre electromagnètic.
Tradicionalment, la llum ultraviolada es divideix en tres categories, UVA, UVB i UVC.
UVA (320-400nm) is an important component of sunlight, and is supplied in small amounts by "ordinary" household bulbs (incandescent lights) and by lighting often described as "full spectrum" light. Larger amounts are supplied by all specialist ultraviolet lamps.
UVA is part of the visible spectrum for reptiles; they see colours and patterns differently to us because of this extra dimension to their vision. Some reptiles rely upon UVA light to identify individuals of their own species by their UVA-reflective markings; many plants and insects also have distinctive UVA reflectance and "patterns" which enable reptiles to recognise them.
Els rèptils exposats a la llum UVA mostren un comportament social i uns nivells d'activitat més elevats, són més propensos a prendre el sol i alimentar-se i també tenen més probabilitats de reproduir-se, ja que la llum UVA té un efecte positiu sobre la glàndula pineal, una estructura-sensible a la llum just a sota. el cervell que respon a l'augment i disminució de la llum del dia amb el canvi de les estacions.
UVB (280-320nm) is found in natural sunlight. The atmosphere blocks wavelengths below 290nm so on the earth's surface, the UVB range is from 290 - 320nm. UVB is blocked almost completely by ordinary glass and by most plastics, so it does not pass through windows or the sides of glass vivaria.
It is not provided by normal household lighting or most so-called "full spectrum" lights, but nowadays there is an ever improving and expanding range of lights that can supply UVB in the vivarium.
Hi ha proves creixents que els rèptils poden detectar UVB, tot i que és incert si són realment visibles per a ells.
Moltes espècies de rèptils, en particular els llangardaixos diürns que prenen la llum del sol, utilitzen la radiació UVB, entre 290 i 315 nm, per facilitar la foto-biosíntesi de la pre-vitamina D3 (colecalciferol) en la pell. Si aquests rèptils es veuen privats d'aquesta longitud d'ona particular de la radiació ultraviolada, corren el risc de desenvolupar una deficiència de vitamina D, que es pot manifestar com un trastorn ossi metabòlic, una malaltia paralizant i sovint mortal que es veu massa sovint en llangardaixos més grans com les iguanes i la barba. dracs.
Els UVB poden tenir altres efectes beneficiosos. S'ha demostrat que estimula la producció de beta-endorfines a la pell humana, donant lloc a una sensació de benestar-. No hi ha cap raó per suposar que aquest procés es produeixi només en humans.
UVC (180-280nm) is harmful to living cells; it is naturally filtered from sunlight by the ozone layer, and is never required, nor should be permitted, in artificial lighting.