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Black color absorbs light better than any other. The thermodynamics explains the propagation of heat but never really answers why exactly specific spectrum of color has different absorption capabilities. What is the physics behind this phenomenon? And is there a specific relationship between the color spectrum wavelengths and the emissivity? I did not find anything directly answering this question, so any links to documents or any good sources are truly appreciated.

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The question suggests a slight misunderstanding about color:

Black color absorbs light better than any other.

Color does not cause absorption. Instead, absorption causes color.

White light - e.g., sunlight - contains all wavelengths. When white light illuminates an object, the object will absorb some wavelengths and reflect/scatter other wavelengths. If all of the visible wavelengths of the white light are absorbed, our eyes will see no light at all, and our brains interpret that as a black color. If wavelengths in the long and short range of the visible spectrum are absorbed but those in the middle range are reflected, the reflected light reaches our eyes and is perceived as green -- and so on. Our eyes have receptors for three different ranges of visible wavelengths, and the specific color we perceive at any point in an image depends primarily on the relative intensity of light in each of those three ranges.

The question of what causes an object to absorb some wavelengths and reflect or scatter other wavelengths requires a much more complicated answer, because it depends on the atomic, molecular, and structural properties of the object's composition.

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Thermodynamics is the classical physics regime. Itt could not explain the frequencies the spectrum of radiation coming from matter, and quantum mechanics was discovered because of this. It is caled the black body radiation

In classical thermodynamics it was known that matter emitted radiation the frequency of which depended on the temperature. But it could not explaine the observed spectra, because the theory gave too much energy to high frequencies, the so called ultraviolet catastrophy.

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So quantization solved the problem, as you will see reading the link.

If you study physics further , you will see that matter is composed of atoms and molecules, and these are in the framework of quantum mechanics. Electromagnetic interactions come out in different frequencies depending on the material. But color perception, i.e. what we see as black or red , and the spectrum of frequencies are not connected one to one. A number of frequencies can give the perception of red, not only the frequency associated in the spectrum with red. It is called color perception..

Our eyes are sensitive to a limited number of frequencies in the total electromagnetic spectrum. All other freequencies are interpreted as "black" by our brain, as far as everydat objects go.

Why do dark colors absorb light more than light colors?

So as far as dark blue versus light blue, there are many things that can be happening

1) at the atomic level there are more interactions absorbing photons for dark blue than light blue

2) at the atomic level the freeqeuencies reflected by the material give the dark versus light contrast

3) the color perception of the eyes may give this impression and a lot of fequencies can be involved.

For black there could be complete absorption of the visible light spectrum, the energy going off into infrared frequencies, sensed as heat, not visible.

A combination of all these dependent on the material/paint.

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