Much has been said about the small but affable face of the first months of the coronavirus pandemic . The quarantines organized around the world notably reduced greenhouse gas emissions, in some places even allowing views that had been hidden for decades by a pollutant cloud. The wild animals also took over the cities, although the truth is that there were quite a few myths about it. But, be that as it may, it is clear that the environment around us changed because of the stand by to which our lives were subjected. And if all that were not enough, now we know that also fewer lightning strikes were recorded for this reason.
It is the conclusion of a study , recently published by scientists from the German Aerospace Center and the Institute for Astrophysics of Andalusia . In it, they analyze how lightning decreased during the quarantine in the area with the most electrical activity in Europe: the Po Valley, in Italy.
But how can these events be related? The key is in the sprays . And no, this time it is not about those emitted by those infected with coronavirus when talking, coughing and breathing.
Less aerosols, fewer rays
In this case, reference is made to polluting aerosols that are issued both due to industrial activity and the traffic of means of transport.
If they are related to rays, it is because the particles that compose them act, in a certain way, as scaffolding so that the drops of water group together and, consequently, generate electrical activity.
These particles are very small, less than 10 microns in This studio. When they reach a cloud, the water droplets that are in it begin to agglutinate around it. Thus, something known as hydrometeor is formed. And of course, logically, the more aerosols there are, the more hydrometeors there will be. Of course, as he has told Hypertextual Francisco Javier Pérez Invernón , author of this study, will also be smaller hydrometeors . This is because, if there are few aerosols, many small droplets will have to share the same core, generating larger droplets. “However, if there are many aerosols, there will not be as many small droplets sharing the same nucleus, so in the end there will be more droplets (because there are more nuclei), but they will be smaller, because in each nucleus there are few droplets together.”
These hydrometeors move through the cloud, intervening in the formation of ice and snow, for example. And in that movement there are collisions between them , so that the cloud becomes electrically charged.
Specifically, the ice is usually positively charged and, as it is light, it rises to the highest layers of the cloud. Snow and hail , on the other hand, are charged negatively and, being heavier, remain in the layers more low. The result is a difference in charge and an electric field that, when reaching a critical value, causes a spark to jump. Next, as Pérez Invernón explains in a thread on his Twitter account, “the electrons are accelerated and a ionization wave is produced that continues to advance in the form of branches until connecting the layers of the clouds, or one of them, to the ground ”. This is how rays appear.
Clearly there is a relationship with aerosols , so a reduction in concentration would be expected of aerosols will facilitate that less rays are produced. But was this the case during the pandemic?
What the data tells us Italians
The Po Valley is not only the area with the most electrical activity in Europe. It also collected many cases of coronavirus during the early stages of the pandemic and, in addition, has a large number of sources of aerosol emissions. The perfect place to carry out this study.
It was observed that, indeed, from March to June 2020 , in full quarantine due to coronavirus, the number of rays in this region was ten times less than at the same time of the previous year. But the rays are not generated only by the presence of aerosols. Other factors also intervene such as meteorological instability , upward movements of air or something basic: existence of clouds.
To see if in this case the reduction in the number of rays could be due to an abnormal development of some of these parameters, the study authors made something known as parameterizations of the ray . These are simple models that help to predict the appearance of lightning, but also to analyze the influence that meteorology has on its generation. In this case, they saw that there was a 60% influence of meteorological origin in the electrical activity collected in that period at this point in northern Italy. However, the remaining 40% could not be explained in this way. Given that there was also a clear drop in aerosol emissions, the relationship seems quite clear.
It is not just a matter of Italy
These scientists studied the phenomenon in a perfect place for it. But, possibly, it is not the only point in the world that has been affected in this way. In fact, Pérez Invernón tells us that something similar has been studied in countries like India and Brazil .
As for Spain, he explains that there may also have been an impact . But in principle it will be more difficult to find it because there are fewer aerosol emissions than in the Po Valley. “ In Spain , although there are nuclei where a lot of NO2 is emitted (one of the polluting substances that is emitted in the form of aerosols), there are not areas as extensive as in Italy with large emissions, so for the moment we have not focused on that region. ”
And in the same way that the Po Valley is not the only place involved, the lightning is not the only effect. The decrease in aerosols due to the quarantines carried out to stop the coronavirus could also affect rainfall, although in a more complex way. This is because, as we have seen before, aerosols are necessary for the water droplets to clump together. “If they are not grouped together, they are so small that they remain suspended in the air and it does not rain,” says the researcher consulted by this means. “But the opposite can also happen. If there are a large number of aerosols, the final droplets will be very small, and they will also remain suspended in the air without precipitating. So there is an optimal concentration of aerosols that favors precipitation, in addition to depending on the environmental conditions “.
In short, the coronavirus has been able to stop the entire world for months, but it not only stopped us in the land surface. It also left the sky itself waiting.