Floodlight helic arc on 15/16 December 2010 in Tampere
This one was seen from automatic gas station lights. The helic arc is rises diagonally from the lamp. I was desperately looking for a place for the spotlight, but the surroundings were totally light polluted. Just 300-400 meters away it was totally dark wilderness, though, but the diamond dust never reached there. So I just photographed the halos in this light. I walked closer to see if I could see 3D structure in helic arc, but as expected, it disappeared. The tangent arc had no seagull shape at the appropriate lamp elevation, indicating presence of Parry arc, which certainly was there. The helic arc is doubled because there are two lights.