Calima is a phenomenon that occurs when it remains suspended dust or other substances in the lower layers of the atmospherewhich causes the sky to be clouded because of sand particles, ashes, excessive salinity, etc.
Spain often suffers episodes of this type with calimas that come from the Sahar desertoh that leave the skies of orange yellow. Meteorologists use the term calima when this event affects the to a greater or lesser extent to visibility.
Saharan dust affection to ecosystems
A CEAB-CSIC and CREAF study, based on Samples collected for thirty yearshas revealed that bacteria and fungi from North African deserts They have a persistent presence in southern Europe, regardless of the episodes of Saharian dust. This finding confirms that its impact on ecosystems and human health is not punctual but continuous. The investigation has been carried out from rain samples collected from 1987 to 2014 in the Montseny massif.
The research team explains that the desert dust – in which there are microorganisms that remain alive – travel constantly, thousands of kilometers, within the persistent currents of the high layers of the atmosphere. It ends up falling with rain or snow, which drags it to the ground. Therefore, analyzing precipitation samples and satellite data, scientists can know What microbes have traveled intercontinental distances.
To avoid confusion with local pollution, which is concentrated in lower layers, the samples are collected in mountain areas, where the rain only drags particles from the high layers of the atmosphere, thus ensuring that the analysis reflects exclusively the microorganisms transported by atmospheric currents long journey.
To be able Characterize the microbiota, researchers have analyzed the DNA of rain samples With massive sequencing techniques, comparing the results with soils of North African deserts and genetic data from other soils around the world. For research, the movement of large air masses that disperse globally microorganisms has also been recreated by computer simulation.