Strange Phenomenon Caught In Hungary

Around Oct 15th, 2009 these photos were taken from an iPhone using the application “iSpy”. Roughly 7:00AM Hungarian time. There was an unusual “ghostly” cloud floating around a tree near a small park in Budapest.

The ghostly cloud was circling the tree at around 5-7 MPH and after witnessing this phenomenon for ten minutes I decided to start taking some screenshots…

Now the strange thing was the cloud was going behind the tree and fully disappearing off camera before returning around the corner of the tree back in full view – which rules out any probable reflections!

When I zoomed in closer the shape lost opacity and finally when people walked by; the shape moved towards the trees, almost like it was “hiding”.

…Can you explain this unusual phenomenon?