Harish Palaniappan's

Its raining heavy here in Chennai, India.. for the past 3 days.. raining with lightning and all. (Note: By heavy, I dont mean we are flooded.)

On seeing lightning, I recollected a lot I learnt about it, and how I miss learning more on electricity rather than rubbing with code in my software job. huh! It always happens.. lets move on.

What's a Lightning?
Lightning has always fascinated me like it has with many people. When you learn about it you start understanding the beauty of it...'the technology'. First myth that I lost, about 8-10 years ago learning about it was, 'Lightning is not just light formed by rains'.

And whenever lightning comes to the mind, I remember the tower Empire State building. Yes, its more a tower than a building... probably some still refer to it as a 'building' because it has that word in its name 'Empire state building'.

To understand what this tower's architecture does to lightnings, we will first study what a lightning is!

Lightning is a huge very-very-high-voltage spark that runs down shunting/short-circuiting the electric gap between the charged clouds and the ground/Earth terminal. And when you read about this, you start trying your own theories about Earth and why its always considered neutral and an absorbant for electric current. We will hit that in another posting.

How does Lightning happen?
The charged clouds, as they move, establish a voltage between the two terminals Earth and the Clouds. Charged particles always look for a closed loop to flow. But never do we have a huge thick copper wire connecting clouds to the earth.. So the gap becomes a dielectric medium made of Air which has a breakdown voltage.. Every gap has its own breakdown voltage beyond which current just jumps the gap. The smaller the gap, the lower the breakdown voltage.

Suppose charged clouds move over a portion of ground, which, say, doesn't have any buildings or anything except for a tree. And say, it's raining. Getting wet in the rain the tree attains some amount of electrical conductivity. When the cloud comes just over this tree the active gap between the cloud and a conductive object decreases. Now the tree becomes the terminal instead of the Earth. At this stage, if the cloud has enough charge that the voltage between the cloud and the tree is higher than the breakdown of the dielectric gap formed inbetween them, then the current jumps the gap damaging the dielectric gap and the other terminal 'tree' momentarily. The damage could split the tree, or burn the tree, or just leave some parts of the tree dead, depending on the amount of current that jumps to the ground flowing through the tree.

Ok, if its a spark it should be yellowish.. how white?
Yes, you would have seen sparks at home while using a switch or sometimes short-circuiting two terminals. Any spark has all the constituents of a fire. For now, without getting into details of sparks, we would go to the easier definition that lightning is a spark created due to very-very high voltage of the order of several thousands of volts.. and so its whitish rather than the sparks at home which are formed by 110 or 240 volts.

Lightning Arresters
Now, lets come to the idea of a lightning arrester. A lightning arrester is a perfectly conductive rod kept on top of buildings and connected deep into the ground through thick copper strips. The idea is, "No don't flow through my building, flow through this rod and the copper strips to the ground." Thus, preventing damage to the building.

The Empire State Building's lightning arrester architecture
Yes, The empire state building has lightning arrester in its architecture.. No, No its not just a rod fixed to the top of the tower.. the tower center pole itself is the arrester.

A very thick conductive rod runs through the center of the tower deep into the ground also being part of the foundation of the tower. This rod extends high out of the tower to make the top of the tower as in the picture.

Every year the empire state building captures 100's of lightnings or rather discharged 100's of highly charged clouds protecting the surrounding from possible lightning damage. The conductive rod is thick enough to allow very huge currents to flow through it to the ground without any damage to the building or the rod.

Records say that the Empire state building was constructed by a person, a depression patient, to overcome his depressive thoughts, and hence the building's majestic architecture. The building gave him the strength to overcome depression and live happy.

Does lightning always happen only between clouds and the ground?
No, most of the time lightning happens between clouds itself. That's why you see light strikes within the clouds. Two clouds oppositely charged get discharged by a spark when they move closer to one another.

In my opinion: If there's a lot of charge in the clouds, can we absorb it, store it and use the current for a longer period?
Yea! A lot of texts mostly at schools describe lightning as a spark which has enough voltage to power 200 homes for a year. Its more easier definition, but technically its not as its said.

Lightning does involve a lot of high-voltage. But, it would not be technically possible to absorb the charge. We cannot absorb charge from a lightning and store it.. because lightning is firstly a 'Discharge', so the charges no longer exist. Probably you could create new charges in a lab taking the current from a lightning. People are working on this and many possibilities. But it isn't going to be possible until we discover/invent more technologies.

Also, there may be a way if we try go to the clouds and absorb the ions through some means before the discharge.

But before everything, how do we store it?
It would be very complex or no technology exists as of today to hold charges stable for any amount of time (Take our batteries, they run out slowly and gradually even if you dont use them). We have technology which can store the charge and discharge gradually over a period of time. And this too, we don't have the capability yet to store so much charge as to power 200 houses or anything.

We feed any electricity generated through means and ways into the power grid, so that someone who is in need of power can use it, or the main power generation units which power the grid can reduce capacity or one or two of them can be off.

There are lot of questions that come up..
How are clouds charged?
How do batteries work?
Can lightning strike an airplane?
How is power generated?
Whats a power grid?
...
...etc.,

Thats' the beauty I was mentioning.. start exploring!!

Have a great day!
'Harish