How are UV rays measured?

Ultraviolet (UV) rays are a type of electromagnetic radiation from the sun that can cause damage to the skin, eyes, and immune system. The strength of UV rays is measured using the UV Index, which is a scale from 0 to 12+.

The UV Index is based on the amount of UV radiation reaching the Earth's surface. It is calculated using a combination of factors, including the time of day, the angle of the sun, the amount of ozone in the atmosphere, and the cloud cover.

The UV Index is divided into five categories:

* Low (0-2): Minimal risk of sunburn.

* Moderate (3-5): Increased risk of sunburn.

* High (6-7): Significant risk of sunburn.

* Very High (8-10): Extreme risk of sunburn.

* Extreme (11+): Unprecedented risk of sunburn.

The UV Index is an important tool for sun safety. By knowing the UV Index, you can take steps to protect yourself from the sun's harmful rays, such as wearing sunscreen, sunglasses, and a hat, and seeking shade during the peak hours of sunlight.

UV rays are also measured using instruments called pyranometers and spectroradiometers. These instruments measure the amount of solar radiation reaching the Earth's surface and can be used to calculate the UV Index.