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I asked this question because I supposedly did last year, Stanfor Klein which belongs to the Solar Energy Laboratory of the University of Wisconsin says that "the color of a car does not affect its internal temperature".

I wonder why Metals with different colors perhaps do not absorb different doses of temperatures? and as a consequence, when different metals of different colors are exposed to strong radiation it is not so differently warmed?

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Your presumption of the meaning of what he said is incorrect. – Ignacio Vazquez-Abrams Aug 30 '12 at 2:32
What do You mean? Color of paint or color of the metal? – Georg Aug 30 '12 at 21:19

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Klein's point was that the heating of cars in sunlight is dominated by their glass windows. This is exactly the same mechanism as in a greenhouse. The glass allows visible light to pass through. The visible light is absorbed by the interior and heats it up, but the glass blocks infra-red light so the heat can't escape.

The colour metal is painted will affect how much radiation it absorbs and therefore how fast it heats up. It's just that this is a small part of heating up a car so the colour the car is painted makes only a tiny difference.

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The OP asked about the different colour of cars, and as far as I know they're all made of steel :-) Apart from copper and gold you don't get different colours of metals. They're all silver, i.e. colourless, because as far as reflecting light is concerned they all behave like a free electron gas. Copper and gold owe their colours to electronic transitions that happen to lie in the optical range. – John Rennie Aug 30 '12 at 17:35
Hello John. While randomly briefing answers, I came across this one. Does this have any misconceptions..? Why was this down-voted? – Ϛѓăʑɏ βµԂԃϔ Oct 11 '12 at 18:17
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@CrazyBuddy: a drive-by downvote I guess :-) – John Rennie Oct 12 '12 at 5:52
How do you know that the heating of cars in sunlight is dominated by the windows?? This is not obvious to me. Also, different paints may have more or less radiative cooling - especially important at night. There again, it's not obvious that the windows are more important than the paint. Personally, I wonder whether Klein's comment is actually true. – Steve B Oct 12 '12 at 16:23
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Well, experiment (admittedly poorly controlled) shows that putting shades over the car windows reduces the amount the car heats up in sunlight. I've also noticed that the illuminated areas within the car feel hot, while the trim on an unilluminated area feels relatively cool. Both these observations suggests that radiant sunlight through the windows is the primary cause of heating.However I can't personally vouch for the validity of Klein's claims, only that they seem plausible. – John Rennie Oct 12 '12 at 17:47

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