Beautifully formed dark ring with white smoke developing into a miniature cumulus cloud from the circumference inward. The photo is one of a series of seven taken by Birthe JENSEN in Nr. Felding, Denmark, on October 19, 1978. The ring was a side effect of a simulated atom bomb explosion carried out at the nearby military base of Holstebro. More about this and similar observations of "ringed clouds" in our discussion of the Viborg case.
[© Birthe JENSEN/SUFOI Picture Library - the English version of the SUFOI web site can be found at www.sufoi.dk (thanks to Ole HENNINGSEN of SUFOI for sending us this image)]