I am not sure how the physics of that works, however, but it certainly absorbs heat, even at low angles of incidence. (wattsupwiththat.com)
It is also because angle of incidence in the polar regions is so low compared with the other regions of the world. (sjsu.edu)
But this experiment shows that even a 2nm (~ 6 atoms) thickness increase to one single layer somewhere inside the structure can be sensed if light illuminates the structure at a very specific angle of incidence. (sciencedaily.com)