I got a latte with whipped cream this morning, and towards the end of the drink I noticed a peculiar effect.
Regardless of how I turned the cup and thereby the coffee, the whipped cream pieces didn't move in position, only floated or stuck to the bottom depending on whether or not there was coffee in the bottom. You can take a look at a video I took to see this effect directly.
What is going on here? What causes it to stay in the same position as opposed to moving with the fluid flow?