NOAA/ESRL South Pole Baseline Atmospheric Research Observatory personnel, Amy Cox and Johan Booth, will soon see the sun return to the polar plateau after 6 months of darkness. NOAA and other staff wintering over at the U.S. Amundsen-Scott South Pole Station will officially “see” the center of the sun cross the horizon at the autumnal equinox time of 10:44 EDT (15:44 GMT) on September 22, 2007. Storms and atmospheric conditions at the geographic South Pole can greatly alter when, and if, the first glimpse of the sun is seen on the horizon. Assuming clear skies and basic atmospheric refraction (the bending of light rays as they penetrate through the Earth's atmosphere), the sun can be seen as much as two days earlier than the equinox. Similarly, the appearance of the "green flash," an atmospheric dispersion effect on colors of sunlight (see http://en.wikipedia.org/wiki/Green_flash), is common at sunrise yet unpredictable. Once the sun has risen above the horizon at South Pole it will continually stay visible until the vernal equinox on March 20, 2009 when it will then set once again for 6 months. Surface air temperatures as cold as -75C (-100 F) are typical into September and the coldest temperatures of the year are often recorded just prior to the sun’s return. The welcome sunlight will warm the polar air at South Pole and when the surface temperature reaches -50C (-58F) the ski-equipped Hercules LC-130 aircraft can begin summer resupply flights from McMurdo station (on the Antarctic coast). The geographic South Pole is located at 2850 meters (9,350 ft.) above sea level on solid ice two miles thick. ESRL staff members each spend a full twelve months stationed at the South Pole observatory and sunrise signals the end of their tour is nearing. Only a few short weeks until the station opens for the austral summer season (~October 23rd) and two new ESRL staff members arrive Pole to relieve the current crew. To view the South Pole sunrise, please go the live NOAA/ESRL web camera at: http://www.esrl.noaa.gov/obop/spo/livecamera.html