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Asked by to Aimee, Chris, Dave, Greig, Laurence on 16 Jun 2014. This question was also asked by .
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Greig Cowan answered on 16 Jun 2014:
The sun produces light in a wide range of wavelengths (colours). Some of these wavelengths are called ultra-violet (UV) since they have a wavelength smaller than that of blue-violet coloured light. You can’t see this light with your eyes since the wavelength is too small, but this doesn’t mean that it can’t have an effect on your body. The UV light carries a lot of energy and because of it’s small wavelength it can penetrate below your skin. This can cause damage to the tissue below your skin which is why we get red and burnt.
Our bodies have a defence mechanism against this which is to produce a dark pigment called melatonin. This is the pigment that gives people freckles but after exposure to the sun more of your skin will be covered with melatonin and you will start to get a sun-tan. The skin that contains melatonin can more easily absorb the UV light, preventing further damage.
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Dave Jones answered on 16 Jun 2014:
The Sun produces light in all colours, just like the colours of the rainbow, except it also produces light either side of those colours in ranges that we can’t see. One side is really harmless, this is the low energy side that contains radio waves and infrared radiaton. The otherside has the high energy rays including the type which are just too blue for our eyes to see called Ultraviolet or UV rays. Most of these are blocked by the atmosphere but some still get through (especially in areas where the ozone layer has been damaged). When this UV radiation comes into contact with your skin in damages the cells, stopping them from working or breaking them. It is this damage to the skin cells which is called sunburn.
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Laurence Perreault Levasseur answered on 18 Jun 2014:
The skin is made of many layers, and the top layer is called the epidermis. At the top of the epidermis are cells that are completely dead. (So when I touch my arm, I only touch the dead cells!!) The ones under, however, are alive, and new cells are constantly being produced to renew the dead ones that fall off.
As the others said, when you sit under the sun, you expose your skin to UV radiation from the sun. Because this type of radiation has a short wavelength and a lot of energy, it can penetrate the skin through the dead layers right to the underlying living cells. But UV light kills cells (it’s actually UV light can be used as a disinfectant or a sterilizer! for example in pools, aquariums, and even devices that sterilize toothbrushes!!), that’s the cause for sunburns.
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Aimee Hopper answered on 19 Jun 2014:
Sunburn is a radiation burn, and is caused by the UltraViolet part of the suns light.
This UV is high in energy, and so can pass through the top layers of skin (the dead part) and reach the new, living cells below, killing them. This causes the body to start trying to heal itself, and so pushes more blood to the surface to aid repair.
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