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What is UV?

WHAT YOU NEED TO KNOW WHEN THE SUN COMES OUT. When the sun shines, it shines with all the colours and wavelengths of light. And each of its radiation types has different effects. But it is the UV rays that are important for your skin.

Useful facts about uv radiation

UVA Rays

When UV rays reach your skin

UVA rays do not cause any painful symptoms on the skin but they do penetrate very deep into the cells of the dermis. They create free radicals and can damage cells in the long term.

UVB Rays

Be careful of too much of a good thing

UVB rays only penetrate into the epidermis. They are responsible for your bronzed complexion, but also for sun-induced skin damage.

The effects of UV radiation are invisible and unnoticeable

UV radiation from sunlight is always all around us. It comes from both direct and indirect sunlight. The UV intensity varies depending on the season and is stronger in summer than in winter. What’s more, the intensity of the UVB rays changes over the course of the day. It can be up to 150 times stronger at midday than it is at 6 a.m. UVA rays are open to far fewer fluctuations. It is therefore important to protect yourself from them at all times. 

The intensity of uv radiation

When does the sun shine at its brightest?

UV radiation reaches us in varying intensity, both directly from the sun and indirectly, for example, through reflection off the sand on the beach. The intensity depends on many factors, including the time of year and the time of day, reflective surfaces, the distance from the equator and the height above sea level. The intensity of UV radiation is therefore different depending on the time, place and surroundings.

UV sun icon

It is not just in summer when there is a great deal of UV radiation

The intensity of UVB radiation, is at its highest during the summer months, at around midday, close to the equator, at higher altitudes, as well as in or near water, snow or other highly reflective surfaces.

Why you need uv protection.

Learn about the potential dangers of UV rays.

Sometimes stronger, sometimes weaker

  • Daily: The intensity of UVB rays is linked to the position of the sun and changes over the course of the day. It can be up to 150 times stronger at midday than it is at 6 a.m. In general, avoid intensive midday sun and prolonged exposure to the sun.
  • Seasonal: The UV intensity varies depending on the season and is stronger in summer than in winter. The risks associated with the UV intensity also vary accordingly. The proportion of sunburn-causing UVB rays is higher in the summer months than in winter. Throughout the year, the proportion of UVA rays in sunlight is open to less strong fluctuations than is the case for UVB rays. The risks associated with UVA rays can certainly be estimated at a more constant level, which is why appropriate UVA protection is important, even for short periods of time in the sun.
  • Geographical: Both the general UV intensity and the proportion of UVB rays increase as you get closer to the equator – unlike UVA rays, in which the proportion is similarly high all over the world.
  • Clouds: Clouds can both intensify and decrease the amount of UV light that reaches us. However, as clouds generally only slightly affect the intensity of UV radiation, sufficient protection is also necessary on cloudy summer days.
  • Shade: Even though shade offers considerable protection against UV light, it does not completely shield us from it. A significant amount of light can be reflected or refracted off surfaces and objects, meaning that even areas that appear to be in the shade are reached by sunlight. We recommend protecting uncovered areas of skin with NIVEA Sun products, even when in the shade.
  • Water, sand, snow and even patches of grass reflect UV rays and increase their intensity on our skin. Grass increases the intensity of UV radiation by 6%, water by 10%, sand by 15 to 25% and snow by more than 30%.

Find more information on the effects of the sun here.

The many types of light

3000-800 NM

Infrared radiation (IR radiation) emits warmth. Although we cannot see its colour, we perceive it as the sun’s heat.

The many types of light

800 - 400 NM

The wavelength range of 400–800nm represents light that is visible to humans, which we see in all the colours of the rainbow.

The many types of light

400 - 320 NM

UVA rays are filtered to a small degree by the ozone layer. However, some rays reach the surface of the earth and can penetrate even the deeper skin layers.

The many types of light


UVC rays would be extremely dangerous for all forms of life if they actually reached the earth’s surface. Fortunately, they are absorbed completely by the ozone layer – even in regions where it is damaged. UVC protection is therefore not necessary.

The many types of light

320 - 290 NM

Some UVB rays are absorbed by the ozone layer, but the majority still reach the surface of the earth. Although the UVB rays only penetrate the epidermis, they can cause sunburn and DNA damage. That’s why it is very important to ensure you have sufficient protection from UVB rays.


UVA rays penetrate the skin more deeply – all the way into the dermis. Although we are usually not aware of them because they aren’t painful, they form free radicals which are able to damage cells and DNA. This can lead to allergies and skin ageing: about 80% of wrinkles are caused by UVA light.


The sun's rays are generally good for the body. They promote the production of the happiness hormone serotonin, so the sun makes us happy.


The sun rays give us a beautiful glow and stimulate the skin’s vitamin D production which is particularly important for bone stability and our health in general. But you should always be cautious of the risks of UV rays. Because of their high energy levels, UVB rays can directly damage the DNA, which can lead to skin damage.

Why you need uv

 Sun and Person

why you need uv clock