dark color soak up heat light colors don't

Actually, rather than thinking of them as absorbers of heat, darker colors are
better absorbers of light and thereby become better radiators of heat.
Consider the following:

The color of an object depends on the wavelengths of colors reflected from the
object. A red apple is red because red wavelengths in white light are
reflected and other wavelengths are absorbed. In fact, if a red apple were to be
illuminated by light that had no red wavelengths, the apple would appear
almost black.

When a black object is illuminated by white light, all wavelengths are absorbed
and none are reflected -- that's why the object appears black. I learned this
the hard way one dark night when I tried to use my flashlight locate a Black
Angus steer that had escaped our pen. All I could see when I shined the light
on the steer were two glowing eyes.

Getting back to the point; when light is absorbed by a black object, the energy
carried by the light doesn't just disappear. Rather, it raises the energy of
the object doing the absorbing. The object, in turn, releases the absorbed
energy by emitting longer wavelength, lower energy infrared (heat). This
transformation of light into heat is the key to understanding the process
because it accounts for the law of conservation of energy. Light just doesn't
disappear when it strikes a black object -- it's transformed into another kind
of radiation that is either radiated from or retained within the black
object.

The darker the object, the better its emission of heat because it is a better
absorber of light.

Regards,

ProfHoff