There are two main types of UV radiation that reach the Earth's surface: UVA and UVB.
Understanding UV Radiation
Ultraviolet (UV) radiation is a form of electromagnetic radiation that is emitted by the sun. Not all UV radiation is the same; they differ in wavelength and energy.
The Different Types of UV Rays
Here’s a breakdown of the different types of UV rays:
| Type | Wavelength | Description |
|---|---|---|
| UVA | Longest | Most of the UV radiation we encounter is UVA. It penetrates deep into the skin and can contribute to skin aging. |
| UVB | Medium | A small amount of UVB reaches the Earth's surface. This type of UV is primarily responsible for sunburns. |
| UVC | Shortest | UVC rays are completely absorbed by the ozone layer and do not reach the Earth's surface. |
UV Rays and the Atmosphere
The Earth's atmosphere plays a crucial role in filtering UV radiation:
- UVA rays have the longest wavelengths and are transmitted through the atmosphere.
- UVB rays are partially absorbed by the ozone layer.
- UVC rays, with the shortest wavelengths, are entirely absorbed by the ozone layer.
Implications for Human Exposure
As most of the UV rays we come into contact with are UVA, with a small amount of UVB, this means we should take care to protect ourselves.
- UVA: While less energetic than UVB, these rays penetrate deep into the skin and can contribute to premature skin aging and wrinkles. They are also thought to play a role in some types of skin cancer.
- UVB: These rays are a significant cause of sunburns. Long-term overexposure to UVB can cause damage to skin cells, increasing the risk of skin cancer.
Practical Tips for Protection
- Wear protective clothing, such as long sleeves and hats, to cover your skin.
- Apply sunscreen with broad-spectrum protection and an SPF of 30 or higher to areas of skin not covered by clothing.
- Seek shade during peak sun hours, typically between 10 a.m. and 4 p.m.
