Not so fast!


You can get sun damage even if the weather is overcast.   Clouds can block visible light but not Ultraviolet (UV) rays.  And, in some cases, clouds can make things worse.

UV rays are damaging to the skin.  UVB rays are linked to sunburn and also skin cancers like malignant melanoma. UVA rays are more prevalent in sunlight and also may also lead to skin cancer as well as wrinkling and photoaging.

Clouds can even make UV light danger worse.  Researchers have reported on the phenomenon called cloud enhancement of UV light.

In a study published in Nature, UVB was measured at the Mauna Loa Observatory.  The levels were 29.8 percent above clear-sky levels. In other studies, levels of UVB (were as higher by as much as 50 percent.

Why do clouds make it worse?  It has been thought that reflection off the sides of clouds may lead to focusing of the UV radiation.

So should you wear sunblock on a cloudy day?  The experts suggest YES unless there is no chance of the sun shining through patches in the cloud cover.

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