Final answer:
UV light causes sunburn due to its higher energy, which can break chemical bonds and damage cells, unlike visible light. The ozone layer absorbs some, but not all, UV radiation, and melanin in the skin provides some protection. Despite these defenses, overexposure to UV can accelerate aging, increase the risk of wrinkles, and lead to an elevated risk of skin cancer.
Step-by-step explanation:
Overexposure to UV light often results in sunburn due to the higher energy that UV rays carry compared to visible light. This is why a person can get sunburned even on a cloudy day, as UV radiation can penetrate clouds and atmosphere. UV radiation has the ability to break chemical bonds at the cellular level in the skin, leading to damage such as sunburn, acceleration of the aging process, and increase in the risk of skin cancer.
While visible light is generally harmless to our skin, ultraviolet light with wavelengths of ≤ 400 nm possesses enough energy to severely damage our skin cells. The ozone layer in the atmosphere absorbs some UV light, particularly wavelengths less than 350 nm, protecting us from the most damaging high-energy UV radiation. However, certain amounts of UV-A and UV-B continue to reach the Earth's surface, which can cause skin damage.
Melanin, a natural pigment found in the skin, provides some protection against UV damage, acting as a natural sunblock. Despite this, large exposures to UV light can lead to significant sun damage and increase the risk of developing skin-related health issues. Repeated exposure to sunlight, especially during childhood or as a teenager, raises the risk of developing skin cancer like melanoma later in life.