I remember when I first came across a latte, and it was life changing. I had never been a fan of coffee, and I still don’t like freeze dried coffee, but then I met the real stuff and I’ve been hooked since. One day at Uni we wandered into Sally’s, part of the food court at the University of Sheffield, and the course of my life was forever changed.
It wasn’t just the lovely coffee I liked; it was the display of physics in front of me. The foam floating on the layer of coffee, floating on the layer of milk. The reason that you can create layers in your coffee is all down to density, there is a slight difference in the density of the coffee and of the milk, and again to the milk foam. This means if they are properly prepared the layers will float on top of each other.