Hot Metals in Sunlight
Name: Michael N.
Why do certain metallic objects become hot when they are exposed to sunlight?
I thought rough black surfaces are best absorbers of light whereas metals are smooth and
When light strikes an object, three things can happen -- light is absorbed, reflected, or
transmitted. Because there are no such things as perfect reflectors or transmitters, anything
will warm up if exposed to sunlight because at least some light will be absorbed. You are
correct in your belief that flat black objects will warm up the most. That is because most
all of the wavelengths of sunlight are absorbed best by a surface color (black) that
reflects the least. Shiny objects are not as good as sunlight absorbers because so much
of the incident light is reflected. It's the absorption of solar flux that warms things up.
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Update: June 2012