Unknown Object in Photograph from Austria

http://www.ufocasebook.com/2009c/austriajune2009.html

Village of Hausleiten, Austria - June, 2009

"It was a Monday afternoon. I went out into the garden to take some pictures with my digital camera of an approaching thunderstorm. I like to picture such events (I'm a hobby photographer). I took some pictures, and later on the computer I watched these pictures and suddenly on one I saw a little white dot in the dark clouds. But it could have been anything, so I guessed. But on another picture there was it again, now closer on the left side of the picture. I was excited. As I zoomed it in bigger it appeared to me to be something I never have seen before in that way. As I took the pictures, I was looking north. But I didn't see anything with my eyes. Only the clouds and the rain of the thunderstorm which was coming closer. Weird..."

[Source: www.ufocasebook.com]