However, it is estimated that around eight million fall each day on Earth, about six thousand per minute. Their dimensions are surprising: there are hundreds of kilometers in length, but on average they are about five kilometers long and their width is only one centimeter.
In this month’s experiment we generated a homemade mini-beam to create fulgurites, glassy structures that arise when an electrical spark produced by the discharge between two clouds or between a cloud and the ground hits a sandy soil such as a beach or desert. The rays reach temperatures of more than 28,000 ºC, so the sand melts quickly, and when it solidifies, fulgurite, a vitrified tube, appears. The first documented discovery of one of these objects corresponds to the German shepherd David Hermann, who made it in 1706 .
A lightning bolt
Fulgurites are usually small and elongated, vitrified on the inside, rough and branched on the sides. Some are traversed inside by an empty canal. This tubular structure is due to the expansion of gases that appear when the sand is heated abruptly. Lightning strikes an average of 100,000 volts and up to 200,000 amps. We don’t even come close to these values. To produce the discharge we use the transformer extracted and recycled from inside a microwave. With this device we get about 4000 volts and 0.2 amps and a temperature of about 2000 ºC, enough to melt the sand.
Once everything is ready, you just need to put on the hand and eye protections, maximize precautions and wait for the gleaming fulgurites to appear.
