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Half hidden in the mountain, this white arc of fog appeared today in Pinós, a municipality in the Solsonès region that is named after one of the five towns that make up it.
When the fog disperses and with the sun behind us, this arch is sometimes formed. It is like a rainbow but white, as you can see in these images in La Vanguardia Readers’ Photos.
In fact, this phenomenon is also called “fog rainbow.” Due to the tiny size of the water droplets that cause fog, smaller than 0.05 mm, it appears white.
The fog arc can also be seen in clouds, typically from an airplane looking down and is then called a “cloud rainbow.” Even when it appears at night it has another name, “lunar mist rainbow.”
To contemplate this phenomenon, the sun would be behind the observer’s head and the direction of view would be towards a fog bank. In this case, we see it on the mountainside.
