Diamond Dust Dogs at Halley Station
April 05, 2007
A lunar halo and Moon dogs appear at Halley Research Station (76 S, 26 W) in Antarctica as photographed on April 13, 2006. The crystals responsible for these captivating arcs and halos are referred to as diamond dust, which are very small ice crystals (less than about 1 mm in diameter) suspended in clear air. Blowing snow is sometimes a source of diamond dust crystals. The Sun is below the horizon at this time of year, but moonlight is sufficiently strong to show off atmospheric optics. Later on this day, the diamond dust cleared, and the full Moon was used to make the first ozone measurement of the season. Note that the more or less vertical object in the fore-ground is not a forlorn tree but rather a sign post showing the direction and distance to the home lands of the Halley scientists.