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Sunburn

Radiation and the atom · level 2, lesson 3 of 6

A question to start

After a long day at the beach, your shoulders are red and sore, though the air was not even very hot. What burnt them?

The idea

Ultraviolet light in sunshine harms the cells in your skin. The skin turns red and sore a few hours later: that is sunburn. Too much ultraviolet over many years can also cause skin cancer and harm your eyes.

Your skin makes a dark colour, melanin, to protect itself. People with darker skin have more of it. But everyone can burn, and everyone needs protection.

How to stay safe:

  • Shade, especially in the middle of the day, when the Sun is highest and the ultraviolet strongest.
  • Clothes and a hat with a wide brim.
  • Sunglasses that block ultraviolet.
  • Sunscreen, put on before going out and again after swimming.
hat, sunglasses,T-shirt, sunscreenand shade

Worked examples

1. Midday. At noon the Sun is high, and its light takes a short path through the air, so less ultraviolet is soaked up on the way. That is when you burn fastest.

2. Snow and water. Snow, sand and water reflect ultraviolet up at you. Skiers can get sunburnt under the chin.

3. A cloudy day. Much of the ultraviolet still gets through thin cloud, so you can burn without feeling hot.

Try it

  1. What causes sunburn?
  2. Why do you burn fastest in the middle of the day?
  3. Name three ways to protect yourself from the Sun.
  4. Why can a skier get sunburnt under the chin?
Answers
  1. Ultraviolet light in sunshine harming skin cells.
  2. The Sun is highest, so its light passes through less air and more ultraviolet reaches you.
  3. Any three: shade, clothes, a hat, sunglasses, sunscreen.
  4. Snow reflects ultraviolet upwards.

Common mistake

"Sunburn comes from the Sun's heat." It comes from ultraviolet, which you cannot feel. You can burn on a cool, windy day.

Where it leads