Why do things turn dark when wet?
In: Chemistry
When things are dry light bounces off them in lots of directions so you tend to see light from all directions bounced back in all directions.
When things are wet the light tends to bounce off in straighter lines (because the surface of water is smoother). When you catch the angle opposite bright light sources you see loads of the total light hitting the surface (so it looks bright). Everywhere else you see much less light because most of it is bouncing off in the few bright directions.
The total amount of light coming off the surfaces is essentially the same. When things are wet some of the angles are very bright while most is dark. When they are dry all angles are evenly quite bright.
Interestingly the amount of perceived darkening is directly related to how rough the original surfaces are. For example polished surfaces don’t get darker at all.
There are more complex interactions at play in most surfaces to do with the surface of the water and the surface of the underlying material, the colour of light, the Fresnel effect and the rate at which light is actually absorbed by a material. But you could study for years and you still wouldn’t get to the bottom of it all.
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