* The authors are part of the community of La Vanguardia readers
The parhelion has manifested itself this Thursday (and twice) in various parts of the coast of Catalonia. It usually lasts a few minutes although it can vary, sometimes lasting hours.
They are very similar to halos (in fact they can and usually happen at the same time), they appear around 22º to the left or right of the sun as bright and even colorful spots in the sky.
Parhelion is an optical phenomenon associated with the reflection/refraction of light, a product of a large amount of ice particles in cirrus clouds.
A cirrus or cirrus is a type of cloud composed of ice crystals and characterized by thin, fine bands, accompanied by tufts. Sometimes these scroll clouds are so extensive that they are indistinguishable from each other, forming a sheet or veil called cirrostratus.
The first time the optical phenomenon of parhelion was documented was on April 20, 1535 in Stockholm (Sweden).
This Thursday at dawn there was coastal fog in the fields of Gavà, as can be seen in one of the photographs in this report in La Vanguardia's Readers' Photos. But, also, on the beach, it was possible to see a spectacular sunrise with trails in the sky and with a surprise: a beautiful double parhelion next to the sun.
In the images we can also see how the solar pillar is drawn on the water of the Mediterranean Sea. A pillar light is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source.
The effect is created by the reflection of light from small ice crystals that are suspended in the atmosphere or that comprise high-altitude clouds (for example, cirrostratus or cirrus clouds). If the light comes from the sun (usually when it is near or even below the horizon), the phenomenon is called a solar pillar
The other element we see are the trails in the sky. Airplanes form a vapor trail after the kerosene combustion process. The gases expelled by the engine come out at a much higher temperature than the outside temperature.
The sharp contrast in temperatures at a height greater than 30,000 feet (-50 degrees in the atmosphere) causes the immediate condensation of the water present in this mixture of substances. This causes us to see these kinds of elongated ice clouds that dissipate after a few seconds.
I share this photograph taken in Roses, in Alt Empordà, first thing this morning from the beach. We can see a very defined double parhelion framing the mountain shortly after dawn.
A very striking optical phenomenon that I have been able to observe on different occasions, although not as marked as today.
