Radiative Properties of Polar Bear Hair

Abstract

The polar bear’s ability to survive in the harsh arctic night fascinates scientific and lay audiences alike, giving rise to anecdotal and semi-factual stories on the radiative properties of the bear’s fur which permeate the popular literature, television programs, and textbooks [1–5]. One of the most interesting radiative properties of polar bear fur is that it is invisible in the infrared region. Some theories have attempted to explain this by claiming that the outer temperature of the fur is the same as that of the environment. However, this explanation is unsatisfactory because surface radiation depends on both the surface temperature and the surface radiative properties [6].