Fig. 1: From ice crystals to snow microstructure.
a Photograph of an ice crystal in the atmosphere (stellar dendrite - K. Libbrecht). b Photograph of natural snow on the ground (decomposing and fragmented precipitation particles - Météo-France). White scale bars: 1 mm. c, d Photographs of natural snow on the ground (rounded grains and depth hoar - F. Dominé). White scale bars: 1 mm. e–g 3D microstructure of three natural snow samples as revealed by X-ray tomography. From left to right: precipitation particles, rounded grains, and depth hoar. h, i Illustration of the absorption enhancement parameter B and the geometric asymmetry parameter gG in a 2D space. In h, the red arrows represent a photon path accounting for refraction and internal reflections, while the white arrows represent propagation in a straight line. In i, the white arrows represent an incoming set of photons, and the red arrows represent an ensemble of possible outgoing photon paths.
