Frost in Lobau national park - this picture too was taken yesterday in the early morning hours:
But considerably later. The sun already had set an hour previously to this photo being taken (which was at 08:13 according to the timer of the camera) - trees prevented the sun hitting this particular part of the 'hot lands' (German Heisslände) of Lobau earlier, so the frost survived a little longer there, and quickly melted away as soon as the sun hit.
You might imagine that I had to wait rather long there. I even stayed there until the sun had flooded the whole area, but I consider this shot being the best as sun and frost are contrasting quite nicely.