Last week I received this stunning photo from Barry Burgess – a great photographer with a very good eye. He took a few photos then slowed the exposure and ended up with this work of art.
That's not something I would even attempt, but I have seen foam form on fast-moving water, and I'm sure you have too.
Ever wonder what causes that foam? It looks like someone might have dropped some soap in the water. Well, no soap here, but a little cool chemistry.
Let's start with a word we don't see every day: surfactant." A surfactant is anything that reduces the surface tension of water; the most common example is soap. While this may seem counter-intuitive, it actually reduces surface tension that makes bubbles possible.
In this case, organic matter is our soap. When organic matter decomposes through natural bacterial action, it releases cellular products into the water. These form a surfactant or surface agent, lessening the surface tension of water, making it susceptible to foaming.
Diminished surface tension allows air bubbles to persist at the water's surface. Vigorous mixing of surface water by waves, water currents, rapids, even boating activity generates bubbles that persist and build up like foam.
After heavy rain, the rivers are high. More rain means more water passing through the ground, more bits of organic matter getting dissolved and swept along, and more turbulence mixing that water up and making bubbles.
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Cindy Day is the chief meteorologist for SaltWire Network