yeasty float on beer

[BerelsBrews]

I am on my second batch of all grain in the first batch the krausen faded and slowly all of the surface of the fermentation was clear aside for a few small floating. in this batch it is a week after pitching yeast and there is a foamy layer of yeast (much lower than the krausen was ) floating on top of the brew, can any one explain this?

 

[freisste]

Usually the krausen falls. Sometimes it does not. I had a wheat that never fell. Three weeks after pitching yeast, I racked to a keg from under the foam.