Ice Crystals and Halos in Fairbanks, Alaska Ice Crystals and Halos at the South Pole

During low level halo displays ice crystals in the atmosphere were collected and photographed. The halos were also photographed. The observed crystal shapes are used as inputs for theoretical computer simulations of the halo displays. Input crystal orientations are chosen to produce halo simulations approximating the observed displays. Especially when the crystal samples are homogeneous, one can sometimes learn the falling modes of the crystals. Also, the observed crystals and halos provide a test of the simulation predictions.