During the 40 odd years of my involvement in the electrical engineering industry, I’ve developed an interest in Lightning, Surge Protection, and Earthing systems. I have also come to realize that there are several myths, and misconceptions, relating to these fields of science and electrical engineering. In the interests of General Safety and Lightning Safety Awareness, I have planned a series of articles, in which I hope to be able to give some clarity to these myths and misconceptions. Let’s start at the top and work our way down, and into the Earth.
Lightning is often one of the most spectacular natural weather events. It is also an extremely dangerous event which often claims the lives of both humans and animals alike. Lightning also causes major structural damage to unprotected buildings and structures. Large quantities of equipment, worth 10’s of millions of rands, are destroyed each year. For this reason, Lightning can be classified as one of nature’s most destructive forces.
Around the world, there are approximately 50 lightning flashers taking place every second, and about 2, 000 thunder storms occurring at any one time. This equates to more than 1,2 billion thunder storms per year. Central Africa experiences the most lightning flashes per square km per year, and the polar regions (North and South Pole) the least. Lightning can strike within a cloud, between clouds, or between a cloud and the ground. During 2016, South Africa experienced more than 28 million Lightning strikes between clouds and the ground.
Possibly due to the destruction and deaths caused by Lightning, several myths and misconceptions have come into being. These myths and misconceptions often lead to further deaths and destruction. For this reason, Lightning Safety Awareness Education and Training is of the utmost importance, and so starts my quest.
ZEUS – Greek God of Lightning
THOR – Nordic God of Thunder
The various North American Indian tribes each have their Lightning Gods. The same applies to African, Indian, Chinese, Japanese, Australian Aboriginal and New Zealand Maori cultures, to name a few. Several papers, documents and thesis have been written in connection with the cultural and religious links to lightning.
IMPUNDULU – African Zulu “Lightning Bird”
TĀWHIRIMĀTEA – Maori God of Lightning
People often believe that Lightning is “the God’s” instrument, which is used to punish people and destroy evil. There is often also a belief that by means of witchcraft, Lightning can be directed to inflict injury to a person(s) and/or destroy their property.
In the interests of saving lives, and limiting the damage to property, a compromise needs to be found between these cultural/religious beliefs, and engineering science. When we can look past the Cultural and Religious beliefs around lightning, and accept that Lightning is a natural phenomenon, only then, will we are able to take precautionary actions, and implement protective measures.
Lightning, being a natural phenomenon, is not actually controlled, or directed by a God, person, or witchcraft. So, what is Lightning?
LIGHTNING THE NATURAL PHENOMENON:
Without going into the in-depth physics of lightning and how it is formed, the most basic description for Lightning is a giant spark of electricity, caused by the build-up of static charges.
This is the same kind of electricity, that can give you a little shock, when you rub your feet on the carpet and touch a person or a metal object.
“Static” means something is not moving. Electricity is created when static charges start to move. A huge amount of electric charge must build up before lightning can strike.
During a thunderstorm, moist, warm air rises quickly into the atmosphere. As it rises, it cools, and forms a cloud. Tiny flakes of ice crystals and a kind of soft hail form in the cloud. The ice crystals and soft hail collide and bounce apart in the clouds. When they rub against each other, the ice and soft hail become electrically charged.
This is similar to how static electricity builds up when your feet rub against the carpet in winter. The ice crystals become positively charged. The soft hail becomes negatively charged. This means they have opposite electrical charges. Opposite charges attract each other. Like-charges push each other away, or repel each other.
In a storm cloud, the ice flakes are small and light, so they float to the top of the cloud. The top of the storm cloud becomes positively charged. The soft hail stays lower in the cloud, and in turn, results in the bottom part of the cloud being negatively charged. The negative charge, low in the cloud, pushes the negative charge in the ground away. The top of the ground, under the cloud, is left with a positive charge.
Once a lot of negative charge has built up low in the cloud, some of that charge starts moving toward the ground. It is met by positive charge rising up from the ground. When they connect, we see the bright flash of light. Sometimes the positive and negative charges meet in the middle of the cloud or move between clouds. Thus, causing lightning to flicker across the sky.
When you hear a crackling in the skies, you’re hearing lightning within the clouds. When you hear loud, booming thunder, you’re hearing lightning jumping from a cloud to the ground.
The thunder that we hear during a thunderstorm, is caused by rapidly expanding air as the super-heated lightning bolt finds its way down a narrow channel to ground. Lightning can heat its path through the air to five times hotter than the surface of the sun. There is not thunder without Lightning. It is the Lightning that causes the thunder that we hear.
As the speed of light is much faster than the speed of sound, we often see the lightning before we hear the sound of thunder. This time difference, between seeing the lightning and hearing the thunder, can give us an indication of how far, or how near, the Lightning is to ourselves. In some cases, thunder could almost be considered a Lightning- warning- system. It is, however, safer to rely on commercially available Lightning Warning Systems.
The American National Weather Service, instituted a Lightning Awareness Program, and came up with a very appropriate slogan and logo:
In future articles, we will look at the different forms of lighting, myths and misconceptions, safety, and misconceptions about earthing systems. The aim is, to try and save lives, and limit damage to buildings/structures and property.