Question #c6b8a

1 Answer
Jul 28, 2017

Veins (which are closer to the surface of the skin) appear blue because of the differential penetration of red and blue wavelengths of incident light.


The apparent colour of the veins under the surface of our skin (for example, on the lower arm just above the wrist) is blue because of the different absorptive properties of the red and blue wavelengths of incident light.

Since light of the blue wavelength is less absorbed than light of the red wavelength, it tends to be reflected by the skin which is why it is the blue wavelength that gets perceived by the eye, making it seem that the veins are blue.

Another addition to this question is that the bluish parts could actually be varicose veins which can be predominantly seen on the legs of someone who always wears high heels and/or standing for long periods of time.