The stelae announce a change of time

* The authors are part of the community of La Vanguardia readers.

Oliver Thansan
Oliver Thansan
18 September 2023 Monday 16:59
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The stelae announce a change of time

* The authors are part of the community of La Vanguardia readers

Condensation trails have once again filled the sky in the Barcelona area this Tuesday, on the verge of a new episode of rain.

Spectacular sunrise today on Gavà beach, in Baix Llobregat, with the sky flooded with airplane contrails, which already announce the change in weather for this afternoon.

This series of images in La Vanguardia's Readers' Photos seem to be the harbinger of the coming rains that, starting tonight and during the early hours, are expected in the Barcelona area, according to Meteocat.

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.

This phenomenon is known in the English-speaking and aeronautical world as contrail - a word that comes from the fusion of the words condensation (trail) or in Spanish, condensation trail.

In this other snapshot we see how the sky has also been filled with contrails on the other side of the Llobregat and Besòs rivers, in the north of Barcelona.

There are airplanes that form contrails while other nearby airplanes do not. Airplanes fly at different altitudes, therefore, the temperature and humidity conditions encountered by one airplane are different from those encountered by another airplane flying close to the first, but at a different altitude.