Wakey wakey
It's often difficult to keep students awake in class at this time of the year but the wake I'm referring to in the title is the wake behind a boat. I seem to travel on the boat between Bergen and home quite a lot and often notice interesting things. This time it was nice enough weather to go outside so I stood at the back where I got a good view of the trail of foam snaking away from the back of the boat. What interested me was that the foam stayed in a parallel sided stripe where as the wake or wave produced behind the boat spread out. It was a nice demonstration of how its the disturbance in the water that spreads out in a water wave not the water itself.
Another interesting phenomenum in the photo was the rather tatty norwegian flag which was exhibiting several different harmonics as it flapped about in the wind.