Raindrop Waves

September 12, 2006


Provided by: John A. Adam, Old Dominion University
Summary authors & editors: John A. Adam

These wave patterns were formed on a drizzly day on ochre-colored ponds known as the Ink Pots, near Johnston Canyon in Banff National Park, Alberta, Canada. Note carefully how the shorter wavelengths appear in the outer parts of the circular pattern, and the longer wavelengths coexist inside them. This is because the small raindrops generate waves that are primarily dominated by the surface tension of the water surface, and the shorter the wavelength they possess, the faster they move. This is in contrast to waves produced on the surface of a pond by larger objects, such as pebbles or rocks; in such cases these waves are dominated by gravity (as are the longer Ocean waves), and in this case the longer waves move faster, so the pattern is effectively the reverse of the one shown here. Try it and see for yourself!

In this location several cool springs bubble out of the ground year-round. The glacial sediments in the springs create beautiful aqua colors. According to Park information, Native Indians used the ochre-colored sediment as war paint; later, settlers used to dig out this material and sell it suppliers of watercolor paint for artists. Remnants of the settler’s equipment can still be seen scattered around the ponds. Photo taken in late May of 2006.

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