With an ultra-fast video camera, the triumph of being in the right place at the right time, or physicist Marcelo Saba, researcher at the National Institute of Space Research (Inpe), and doctor Diego Rhamon, obtained an unpublished image of a radio download, showing Details of your connection with various radios located in the immediate vicinity.
A rarity of the image seems to have been reproduced in the layer of Geophysical Research Letters (GRL), one of the most important scientific journals in the area. The work was supported by FAPESP.
“The image was captured on a summer night, in São José dos Campos [SP], when a descending rate of negative charge was approaching only with a speed of 370 kilometers per second. At the moment in which the discharge was just a few tens of meters from the ground, several lightning rods and projections of buildings located in the region produced positive ascending discharges, competing to connect with the lightning that was sending. The final image prior to the connection was obtained 25 millionths of a second before the lightning impact on two properties”, says Saba.
It was that spectacular image that the GRL editors reproduced on the publication layer.
The researcher reports that his camera captured 40 thousand images per second. Shot in superslow motion, the video shows how lightning rods behave. And also that the rays can be a danger if these protection equipments are not correctly installed.
This is because, despite having more than 30 radios in the vicinity, the radio did not connect with any of them, but, yes, with a chimney from a furnace located in the coverage of two buildings.
“A mistake in the installation left that unprotected area. The impact of a current of 30 thousand amperes produced an impressive havoc”, he says.
Attend at the moment:
On average, 20% of the two radios are made up of electric cargo trucks between the clouds or only. The remaining 80% are composted by electrical discharges inside the clouds.
Two that play alone, to quase totality are descending rays: começam na nuvem e vêm para o solo. Ascending rays also exist, but they are rare. This happens from tall structures, such as mountain tops, arranha-céus, towers and antennas. Depending on the charge that we transfer to or alone, the rays can still be classified as negative or positive.
“The rays can reach up to 100 kilometers of comprehension. And transport currents of the order of 30 thousand amperes. Isso is equivalent to the current used by 30,000 100-watt lamps working together. In some cases, the current can hit 300 thousand amps. At a temperature of 100,000 oC, it is five times higher than at the temperature of the Sun’s surface”, says Saba.
How are rays formed?
The researcher explains that everything starts with the electrification of the clouds. Its mechanism is still not fully known. More runs, roughly, of the friction between ice particles, water droplets and hail, which releases charges and creates polarities between different regions of the clouds, with differences in electrical potential that vary from 100 thousand to 1 billion volts.
“It is necessary to take into account that the clouds of storms are enormous structures, that have their base 2 or 3 kilometers from the only one and whose mole can reach up to 20 kilometers of altitude. Their diameters range between 10 and 20 kilometers”, he says.
The branched shape assumed by hair is explained by the fact that the electric charges seek the easiest path, this is, which offers less resistance, and not the shortest path, which would be the straight line.
The easiest path, generally zigzag, is determined by different electrical characteristics of the atmosphere, which is not homogeneous. “A radio made up of several downloads can last up to 2 seconds. No meanwhile, each download lasts just fractions of a thousandth of a second”, adds Saba.
He points out that the lightning rod does not attract or repel the lightning. He also does not download the clouds as was thought in the past. He simply offers you an easy and safe path alone.
As it is not always possible to count on the protection of a lightning rod, and summer is the time when most atmospheric electrical discharges occur, it is advisable to consider Saba’s recommendations. “Storms occur more late than morning.
Likewise, be careful with the activities you spend free on summer afternoons. To hear a trovão, look for shelter. Never pack trees or posts. Not even on precarious coverage.
In case of not having a robust place to protect yourself, stay inside the car and wait for the storm to pass. If you don’t have a car in any other place where you can take shelter, I was cocoras como los pés juntos. Never give up, nem deitado. Inside the house, avoid contact with electrical appliances or use of telephones with confidence”.
The researcher affirms that a person struck by lightning can survive. And there are several examples disso. The chances increase when the person is promptly attended to. “Cardiac arrest is the only cause of death. In this case, the recommended care is cardiopulmonary resuscitation ”, he teaches.
He began the systematic study of lightning with high-speed cameras in 2003. This study, still in force, provided the largest bank of videos of lightning filmed at high speed in the world. The researcher and his orienting students have been provided with 17 aids or bags provided by FAPESP.
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