Fancy Fogs
Today, we sing the merits of fancy fogs. The University of Houston presents this series about the machines that make our civilization run, and the people whose ingenuity created them.
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Fog comes in so many forms. So let’s begin with the most ordinary. The common fog we’ve often seen in the early morning. It’s made of tiny droplets – maybe ten millionths of a meter in diameter. So small that air resistance keeps them from falling perceptibly. That’s why a fog persists until the sun burns it away.
But the fun begins when sunlight lands on fog. That lighting takes many wondrous forms. Most familiar: the rainbow. Not rain at all, but fog that’s being lit by the sun behind us. Solar rays then turn each droplet into a kind of Newtonian prism – scattering light in all the visible wavelengths – the full color spectrum. But somewhere, over the rainbow, are more eerie kinds of fogs. Take the Fog Bow.
Rainbow next to Niagara Falls “Maid of the Mist” (photo by JHL)
One morning, years ago, I’m taking pictures along the Oregon coast. Suddenly, just to my left, I see an amazing white arch. It made sense only after I learned about Fog Bows – rainbows made of droplets that’re too small to clearly define individual colors. Hence, we see only that white arch. And that, by the way, is a rare treat.
Fog Bow (Photo by JHL)
Now the strangest of sunlit fogs. Talk about the music of those watery spheres. It is perhaps best known for its appearance in Franz Schubert’s song cycle, Winterreise – a sequence of twenty-four poems set to music. All about a man who, during winter, flees from his grief over a lost love. Song number twenty-three is titled, “The Three Suns.”
There he sings of seeing not one, but three suns in the sky. And we puzzle over what that poet, one Wilhelm Müller, was thinking. Did our lovelorn wanderer have three loves – only one of which he was grieving. Who knows? The whole song cycle is wonderful music woven around that perplexing protagonist.
But the three-sun image turns out to be a reality. A reality the poet surely had in mind. Something called a Sun Dog. One more fog-based optical treat. Sun Dogs occur near sunset. Here’s how they work: Suppose a fog of tiny ice crystals lies between us and the horizon. We’re looking at the Sun in the center. But two more suns lie twenty-two degrees to the left and to the right.
A “Sun-Dog” illusion seemingly showing three suns (Image courtesy of Wikimedia Commons)
Musicologists are pretty sure that the poet imagined this fellow seeing a Sun Dog – then making it a part of his lament.
(Music - Winterreise, Franz Schubert)
But back to fancy fogs in general: The refracting effects of light on water create so much beauty in the nature around us. Just walk about a waterfall to catch the effects of the sun glinting upon it. Small wonder that the many forms of water have cried out for music to tell of them.
I’m John Lienhard, at the University of Houston, where we’re interested in the way inventive minds work.
(Theme music)
Sources
The Entire Winterreise performed
Just for the fun of it, here is my optical method for measuring the diameter of small droplets. DropletDiameter.pdf
This Episode first aired on August 5, 2026.