Rare image of a lenticular cloud over the Low Countries. This one appeared over Antwerp city on May 16, 2001 at 8:35 pm. The picture was taken using an Olympus digital camera (model C200Z) with sunglasses held in front of the lens. The formation of lenticuar clouds over a flat terrain is difficult to explain. Possibly, in this case, it were the towering cumulus clouds visible in the foreground that were instrumental in forcing air currents into a standing wave pattern.

[© Wim VAN UTRECHT/CAELESTIA]