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This morning it was possible to see a spectacular cumulonimbus arc in front of the coast of Barcelona, as can be seen in this photograph that I took for Las Fotos de los Lectores de La Vanguardia from Gavà beach, in the Baix Llobregat.
This morning's storm has left us this beautiful postcard of the monster in the sky, the bow cloud. This is the colloquial name given to the so-called cumulonimbus arcus, a term from the Latin meaning "storm accumulation."
And this cloud is associated with electrical storms and is usually one of the most investigated by meteorologists, especially by the so-called "storm chasers."
They arise from a downdraft from an advancing storm that causes warm, moist air to rise, cool below its dew point, and form the cloud.
There are two main types: the shelf cloud and the roll cloud. This last one is the most spectacular. As can be seen in the photograph, the enormous arch has completely blocked the sun in the early stages of the day on Gavà beach.
