Have you ever noticed the water is warmer at the surface when you swim in a lake? What's going on? CFL graduate student, Colin Smith, walks you through thermal stratification using animations, experiments and an awesome live demo as he explains what is, perhaps, the most important physical process in temperate lakes. It's science made clear. It's "Limnology 101." *Note: This video is a demonstration of the principles of stratification. Some footage may not be rigorously scientifically accurate.