The process of lightening is very complex. When a thundercloud moves, there is a powerful negatively charged center in its lower middle part. As the opposite underlying surface of the cloud turns into a center of positive charge, a strong electric field comes into being between the bottom of the cloud and the ground.
As there is more and more charge and the electric field gets more and more powerful, a highly ionized air column appears beneath the cloud. This ionized air column keep extending downwards step by step until it is 5-50m away from the ground when it bounces back in a sudden and sends out a splendid beam.
Lightening takes about 0.25s once. During such a short time, a large amount of electricity needs to be released inside the narrow lightening channel. As a result, massive explosions follow and create shock waves. These waves are transformed into sound waves when they are spread all around. That is what we call thunder, or thunderclaps.
Lightening is classified by its shapes: Normal vented lightening with twists is called streak lightening; if the channel of streak lightening is blown to both sides with the result that several paralleled streams of lightening can be seen, it is called ribbon lightening; if two bolts of lightening seems to reach the ground at the same time, then it is called forked lightening.
If sparkling lightening appears between positive and negative charges in the cloud and lights up the whole sky, it is called sheet lightening; if the lightening has not reached the ground, that is to say, if it is in one or two cloud layers, it is called cloud-flashes.
Sometimes this kind of overbearing lightening will move for a while and land on somewhere a few kilometers away from the storm. Under this condition, it is ‘a thunderbolt out of a clear sky’.
The power of lightening can make a halo of red light around something tall and sharp at times. Usually people can see a ray of light that is burning red around the mast of a ship during storms at sea. Named after the patron saint of sailors, this lightening St Elmos Fire.
Super lightening refers to the rare lightening that is over 100 times more powerful than common one. Common lightening carries about 1 billion watts of electricity, while super lightening at least carries 100 billion watts, or even possibly from 1 trillion to 10 trillion gigawatts.
The Bell Island in Newfoundland once was hit by super lightening. Even 13 kilometers away, the houses was rattling under the shock waves. Blue flames was spouted from doors and windows all around the village.
Comment list ( 0 )
