How is lightening formed??

Answer 1

Lightning is a giant static shock between clouds or between coulds and the ground. It occurs when a charge difference builds up between the ground and the sky.

The charge difference must be relieved, so a gigantic shock is issued from one side to the other.

Learn more below:
http://en.wikipedia.org/wiki/Lightning

Answer 2

It starts with static electricity. All static is generated by friction, and the static in lightning is no exception. When small particles of water start to condense and fall, they 'rub' against air molecules, and electrons move from the gas molecules to the water molecules (it's called the triboelectric effect). The electrons are carried away by the falling water.

Multiply this 1000 times, even 1000000 times, and eventually you have enough electrons that have travelled down away from the top of the cloud to the bottom of the cloud. Now you have this massive charge of electrons with a lack of electrons at the top. A huge potential difference (voltage) exists, and when it reaches a high enough value, it is enough to break-down the insulative effects of normal air, and turn it into plasma, which conducts current providing a path for the electrons to flow back to where they came (or to another suitable place like the ground), and a lightning bolt is generated.

The only thing I am not sure of (but I don't want to look it up right now) is... whether the water drops carry the electrons, or are stripped of electrons when they rub against the air molecules. Either way the overall explanation is the same.
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Answer 3

When there is a very large difference in electrical potential between the ground and a cloud, a large amount of energy transfers itself across the space. This energy transfer takes place in the form of lightning, a long bolt of electricity.

Answer 4

From the energy in the electrical field between the thundercloud and the ground.

"A CG lightning discharge is typically initiated inside the thundercloud. It is first apparent when a faint negatively charged channel, the stepped leader, emerges from the base of the cloud. Under the influences of the electric field established between the cloud and the ground, the leader propagates towards the ground in a series of luminous steps of about 1 microsecond (1*10 -6) in duration and 50 to 100 meters in length, with a pause between steps of about 50 microseconds. The stepped leader reaches the ground in tens of milliseconds (1*10 -3) depending on the tortuosity of its path. when the stepped leader channel approaches the ground, it has about 5 Coulombs of negative charge on it and carries a very strong electric potential with respect to ground of about -10*8 volts.

The strong electric field between the leader and the ground causes upward moving charges, or streamers, from objects on the ground. When one of these streamers contacts the tip of the leader, 50 to 100 meters above the surface, the following occurs:

The leader channel is connected to the potential to ground

Charge starts flowing to ground

Current wave propagates as a bright pulse up the channel

This discharge process is called the return stroke. and takes less than 100 microseconds. The charge deposited on the leader flows down the channel behind the wave front producing a current at the ground that has an average peal value of about 30 kiloamperes. It takes about 1 microsecond for the current to reach its peak value, and about 50 microseconds to decay to half that value.

As the leader charge flows down the channel to the ground, electric and magnetic field changes are produced that propagate outwards from all the segments of the channel involved in the current flow. These field changes have rapid variations that follow the channel of the stepped leader. The field changes have electrostatic, inductive and radiative components, and each of the components has fluctuations of different frequencies that have different attenuation characteristics as the fields propagate from the lightning channel. Therefore, the shapes of the field changes are strong functions of the radial distance from the channel. The detailed structure of the first several microseconds of the electric and magnetic field changes produced by the return stroke is of fundamental importance in cloud to ground lightning detection systems.

After the current has ceased to flow down the stepped leader channel, there is a pause of about 20 to 50 milliseconds. After that, another leader can propagate down the already established but faint lightning channel. This leader is not stepped, but rather continuous and is called a dart leader. On the other hand, no dart leader might occur and the flash may end. A dart leader is produced when additional charge is made available to the top of the decaying channel in less than about 100 milliseconds by the breakdown mechanism known as K and J processes. The dart leader deposits about one coulomb of charge along the channel and carries cloud potential to the vicinity of the ground. Again, a return stroke is produced. The peak amplitude of the current flowing in subsequent return strokes is usually, but not always, smaller than that of the first return stroke. As a consequence, the induced field changes are also usually smaller in amplitude and have a shorter durations than those of the first return stroke. dart leaders and the return strokes subsequent to the first are normally not branched. the combinations of the leader and the return stroke is known as a stroke. All strokes that use essentially the same channel to ground constitute a single cloud-to -ground flash. A flash might be made up of one to a few tens of strokes."

Answer 5

A potential is created by air molecules moving against one another. Lightning is the result of the discharge.