Much has been made of the small but affable face of the early months of coronavirus pandemic. The quarantines organized around the world dramatically reduced greenhouse gas emissions, in some places even allowing views that had been obscured by a pollutant cloud for decades. 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 due to the stand-by to which our lives were subjected. And as if all that were not enough, now we know that too fewer rays were recorded for this reason.
It is the conclusion of a study, recently published by scientists from the German Aerospace Center and the Andalusian Institute of Astrophysics. 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 aerosol 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 emitted so much because of the industrial activity as for the traffic of means of transport.
Sprays act as scaffolds for water droplets to clump together
If they are related to rays, it is because the particles that compose them act, in a certain way, as scaffolds 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 found in it begin to agglutinate around it. Thus, something known as hydrometeor. And of course, logically, the more aerosols there are, the more hydrometeors there will be. Of course, as Francisco Javier Pérez Invernón, author of this study, has told CVBJ.biz, they 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 displacement they are collisions between them, so that the cloud becomes electrically charged.
Specifically, ice is usually positively charged and, as it is light, it rises to the highest layers of the cloud. Snow and hailinstead, they load negatively and, being heavier, they remain in the lower layers. 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 accelerate and there is a ionization wave 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 aerosolsSo a reduction in the concentration of aerosols would be expected to facilitate fewer lightning strikes. But was it like this during the pandemic?
What the Italian data tells us
The Po Valley is not only the area with the most electrical activity in Europe. Also picked up many cases of coronavirus during the early stages of the pandemic and also has a large number of aerosol emission sources. The perfect place to carry out this study.
It was observed that, indeed, March to June 2020, in full quarantine due to coronavirus, the amount of lightning 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 play a role, such as meteorological instability, the upward air movements or something basic: the existence of clouds.
To see if in this case the reduction in the number of rays could be due to an abnormal development of any of these parameters, the study authors did something known as beam parameterizations. 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. Nevertheless, the remaining 40% it could not be explained in this way. Given that there was also a clear drop in aerosol emissions, the relationship seems clear.
It’s 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.
It could also affect rainfall, but in a more complex way
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 SpainAlthough 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 just as the Po Valley is not the only place involved, lightning is not the only effect. The decrease in aerosols due to the quarantines carried out to stop the coronavirus also could 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, 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 on the earth’s surface. He also left heaven itself waiting.