Opposition effect from the air
Image Index     Opposition Effect glow, Uzbekistan. Photograph by Eva Seidenfaden (Atmospheric optics site) - " .. taken on the 17th of September about half an hour after takeoff from Tashkent at 15.30 local time. The yellow spot kept following the plane, but eventually vanished behind it because we were flying from the east to the west. There was no water in the air, nor ice crystals, just dust and sand." Look carefully towards the antisolar point for this very subtle glow drifting across the landscape as the aircraft flies onwards. It is slightly yellow because of the absence of shadows. Shadows are bluish because they are lit predominantly by blue skylight. The glory and heiligenschein are other antisolar brightenings but they need water droplets. An afternoon glow in a desert is a fairly sure sign that the opposition effect is operating.