The “pyrocuse” have arrived in Spain to stay

Heat is always a risk factor in terms of forest fires, even more when it is as intense as we have seen during the last weeks (and that in some areas still unleashed). We might think that storms that have put limits to this heat would play in our favor, but the problem is that this is not always the case.

Sometimes they bring a greater problem.

Fire in Lleida. The fire that has devastated part of the province of Lleida in recent days has stood out for its rapid propagation. He Balance of this fire yesterday It was two deceased people and 6,500 hectares.

The fire, cataloged as “sixth generation”, reached speeds of propagation of up to 28 kilometers per houra speed that makes flight away on foot. To do this, it had the cooperation of a key factor, the pirocumuli.

Pyrocuse. Flammagenitus pyrocumulus or clouds are atmospheric events in which powerful fires and concrete weather conditions that generate a “fire cloud” converge. This process is feeded, firing the devastation capacity of the fire itself.

These clouds of smoke can reach heights above 10 kilometers: in the Lleida fire there is talk of a cloud wall of up to 14 kilometers high.

Convective clouds. And how exactly these clouds are formed? The pyrocumulus or pyrocumulonimbo name is created in reference to the shape of the generated cloud, similar to clusters or cumulonimbos and not by chance. In both cases the form is a consequence of the processes that generate these clouds.

In the case of “conventional” clusters, The triggers They are a high soil insolation that makes the air hot in low layers, when warm air is heated and runs into cold air in more antlas layers causing the appearance of a cloud. In the case of fires, it is nothing but fire itself that heats the air, causing it with it to ascend gases, particles and ashes from the fire.

From the cloud to the storm. The clouds of inconscious origin behave in many ways like conventional ones. They reach an important height where the most intense winds begin to drag them. The moisture accumulated in these clouds It can generate storms with rainfall as well as with electrical discharges in the vicinity of the fire.

Sixth generation. The appearance of these clouds and associated storms not only facilitates the spread of fire, but also generates immense uncertainty regarding their evolution. This uncertainty is precisely one of the defining features of the so -called Fire of “Sixth Generation”.

The fires of this type are becoming a growing threat in our environment. The most virulent example is found in 2017, when a fire in Pedrogão Grande, Portugal, left 60 people killed.

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Image | Eric Neitzel