ultraviolet rays

Ultraviolet rays are invisible rays that come from the sun. They are also emitted by some artificial sources, such as tanning beds.

UV rays can cause sunburn, skin cancer, and other health problems. They can also damage plants and materials.

There are three types of UV rays:

• UVA rays: These rays are the longest and least harmful. They can cause skin ageing and wrinkles.
• UVB rays: These rays are shorter and more harmful. They can cause sunburn and skin cancer.
• UVC rays: These rays are the shortest and most harmful. They are blocked by the ozone layer in the atmosphere.

Ultraviolet rays are invisible to the human eye, but they can be detected by some instruments.