Why can the sun be dangerous?
Last week, Mika and I went hiking in the mountains. We climbed quite high up. Of course, we always applied sunscreen so that we wouldn’t get sunburned. However, Mika said that he didn’t need it because his fur protects him.
But why do we need to protect ourselves from the sun at all? I understood the need for sunglasses. Without them, it’s just too bright and you have to squint all the time. But the warm rays on your skin actually feel quite nice.
So we asked Johannes Röttenbacher and he told us all about UV radiation, thin air and sunburn.
The light that comes from the sun to Earth consists of different colors. When all colors hit our eyes at the same time, we perceive them as white. Sunlight contains all these colors. But that’s not all! Sunlight also contains colors that we cannot see.
However, if the light is refracted, for example by a prism or raindrops, then the individual colors can be seen. This creates a colorful rainbow. The innermost color of the rainbow is blue or purple. This is because it is refracted the most. There is also a strip of ultraviolet (UV) light, but we humans cannot see it – it is invisible. This ‘light’ is called UV radiation and has a lot of energy. When the sun’s rays hit a rock or a bench, this radiation is converted into heat. That is why our skin feels warm when the sun shines on it.
However, because UV radiation has so much energy, it can also burn us—we get sunburned. This is a bit similar to fire or a hot stove. But unlike fire or a hot stove, we can protect ourselves against UV radiation with sufficient sunscreen. On the one hand, the white ingredients in the cream ensure that more UV radiation is reflected by our skin. On the other hand, there are other ingredients that absorb UV radiation.
However, it is not enough to apply sunscreen just once. Over time, it loses its protective effect, especially when we sweat or go swimming. That’s why we reapplied it after the strenuous climb to the summit. In addition, the air above us also absorbs some of the harmful UV radiation. This is due to the water vapour in the air. At the summit at 2,100 metres, however, we don’t have as much air above us as we do down in the valley. The air is thinner, so to speak, and protects us less from UV radiation. That’s why you have to be particularly careful about reapplying sun cream in the mountains.
But just as important as reapplying sun cream at the summit was the delicious snack. Thus refreshed, we made it back down safely.
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Text: Johannes Röttenbacher, Illustration: Patrizia Schoch, Translation: Fathima Cherichi Purayil