On the surface of the air bubbles dissolved in the water that flows rapidly, the entire spectrum of the incident light is reflected in all directions. This is why the foam is white. The foaming of the flowing waters is favored by the existence of chemical impurities, which often are pollutants. The image was taken using a Nikon D40X camera with Nikon 55-200mm VR AF-S f/4-5.6G ED lens and these settings: exposure time – 1/20 seconds, focal length – 150mm, ISO – 100, F- number – 14.