At any given moment some 2,000 thunderstorms are in progress over the Earth's surface, and lightning is believed to strike the Earth, on average, 100 times a second. Inhabitants of Ireland may be forgiven for believing that the entire ensemble for the day was concentrated on or near our island last Friday.
Lightning, as that day clearly showed, has great capacity for causing damage. In olden times fervent prayer was, by and large, the only remedy. Its efficacy could be supplemented by the proximity of so-called "lightning preservers", plants or animals that were believed to be immune from lightning strike. For example, in Roman times one such preserver was the eagle, which derived its immunity from its sacredness to Jupiter, himself the fons et origo of the deadly "thunderbolt". The olive branch, besides being a symbol of victory, was another reliable preventive measure.
The medieval remedy was a herb called "houseleek", or "Jupiter's beard", which, when grown on the roof of a house, was believed to ward off lightning, fever and evil spirits.
Our precautions nowadays are more scientific. After Benjamin Franklin's confirmation of the electrical nature of the lightning stroke, "Franklin rods" caught on quickly. They became widespread in the American colonies during the late 1750s and have been used almost worldwide ever since.
In recent times, however, efforts are being made to harness laser technology to "extract" the lightning from a thundercloud, as it were, before it has the chance to be destructive.
A laser produces a very powerful, finely-focused beam of light of a specific wavelength, and has the capability of dislodging negatively charged electrons from some of the atoms in its path. After a laser pulse has been aimed at a thundercloud, the path it occupied contains a large number of electrically charged particles. This "ionisation" of the air provides a conducting path to facilitate a flow of current.
The idea is to use the laser to discharge a cloud harmlessly, by means of a guided, controlled stroke, before the electrical tension becomes strong enough for a random surge of lightning to take place. To prevent the laser itself from being struck, the beam is not pointed directly at the cloud; it is aimed at a mirror, suitable positioned on the ground and well earthed, which in turn redirects the laser beam to the chosen thundercloud.
When perfected, it is hoped that a portable version of this device might be suitable for temporary installation at sporting events, or at other places where large gatherings of the population might be vulnerable.