How Much UV Reflects Off Sand, Water and Concrete? Why Ground Glare Reaches Your Eyes
UV Science
How Much UV Reflects Off Sand, Water and Concrete? Why Ground Glare Reaches Your Eyes
A cap shades your eyes from the sun above. It does nothing about the light bouncing up from the sand, the sea or a white pavement. That reflected UV is a large part of why beaches, snow and bright cities are hard on the eyes.
In this article
- How much UV do different surfaces reflect?
- Why does reflected UV matter for your eyes?
- Does water reflect a lot of UV?
- Does this matter in Indian cities too?
- What sunglasses protect against reflected UV and glare?
- Rawbare polarized picks for beaches and water
- Frequently asked questions
How much UV do different surfaces reflect?
Fresh snow reflects up to about 80% of UV, dry sand roughly 15 to 25%, sea foam around 25%, and water, grass and soil usually less than 10%. The fraction reflected is called albedo.
These figures come from measurement studies and are used by the World Health Organization in its UV index guidance. Values vary with conditions. Wet sand reflects less than dry sand, old snow less than fresh snow, and water reflects far more when the sun is low and the light hits it at a shallow angle.
| Surface | Approximate UV reflected |
|---|---|
| Fresh snow | Up to 80% or more |
| Sea foam | Around 25% |
| Dry beach sand | 15% to 25% |
| Calm water (sun high) | 5% to 10% |
| Grass, soil | Under 10% |
Why does reflected UV matter for your eyes?
Because it reaches your eyes from below and from the sides, where a cap, the brow and many sunglasses give little protection, and it adds to the UV you already receive from the sky.
Your brow and eyelids naturally shade the eyes from overhead sun, which is part of why the eye is reasonably protected around midday. Light reflected from the ground comes in under that shade. On snow, reflected UV can nearly double total exposure, which is why snow blindness (a sunburn of the cornea) is a known risk in the mountains. See sunglasses for snow and glare.
Beach sand is less extreme than snow but still significant, especially across a long day. Reflected light from the ground also reaches skin that is in shade, which is why people burn under beach umbrellas.
Does water reflect a lot of UV?
Less than most people think when the sun is high, often under 10%. But reflection rises sharply when the sun is low, such as early morning and late afternoon, and the glare from water is intense in visible light.
The amount of light water reflects depends on the angle. When the sun is overhead, most light enters the water. When the sun is near the horizon, the surface acts more like a mirror. Moving water and spray also change how much is scattered.
Visible glare from water is a separate issue from UV. Glare is about comfort and clear vision. Polarized lenses cut this glare effectively, which is why they suit beaches, boating and fishing. See sunglasses for fishing and is polarized the same as UV protection.
Does this matter in Indian cities too?
Yes. Pale concrete, light paving, white-painted walls and glass reflect light and some UV back toward street level. Combined with India's high UV index for much of the year, this adds up during long hours outdoors.
Many Indian cities record UV index readings of 8 to 11 or higher in summer, which the WHO classes as very high to extreme. Concrete is not as reflective as snow, but people spend far more hours on it: commuting, waiting at stops, riding two-wheelers and working outdoors. Light-coloured walls and glass facades can also reflect visible glare at eye level.
For more on reading daily UV levels, see how the UV index works. Outdoor workers can read sunglasses for people who work outdoors.
What sunglasses protect against reflected UV and glare?
UV400 lenses in a frame with good side and lower coverage. For water and sand, add polarization to cut glare. A wrap or curved frame that sits close to the face blocks the most light from below and the sides.
For a complete beach and travel kit, see travel sunglasses: one pair for flights, beaches and treks.
Rawbare polarized picks for beaches and water
Polarized UV400 lenses in wrap and wide frames. All in stock on rawbare.com.
Frequently asked questions
Key takeaways
