3. Why some people have freckles
Melanin is the main player here. Freckles are the parts of your skin with a higher concentration of melanin that isn’t distributed evenly, but instead, in small groups. However, the mechanism remains the same: the areas of the skin with a higher concentration of melanin become active when exposed to sunlight. That’s also why some freckles often appear in the summer and then disappear during the winter.
Interestingly, freckles seem to appear faster than a regular tan mostly because they’re grouped in small areas of the body, making them more noticeable in contrast. But melanin is actually active in all types of skin at all times.
4. Why the skin gets red when it gets sunburned
Melanin, once again, is responsible for tanned skin. The nice sun-kissed color we all long for is nothing more and nothing less than the skin’s reaction to what it considers to be a UV ray attack. Melanin acts as a kind of barrier and increases its concentration, absorbing these rays to avoid irreparable damage. This is why we see ourselves looking tan after moderate exposure to the sun.
But not all types of skin produce the same amount of melanin. Sometimes the quantity produced is not enough to prevent UV rays from reaching deeper layers of our skin. In that case, those layers end up being damaged, and we call it a sunburn. Sunburns happen when the time we spend exposed to the sun, or the way in which we do it, exceeds the protective capacity of this natural barrier. Lighter skin can already burn in about 15 minutes while darker skin can be exposed to the same radiation for longer periods without anything happening to it.