Why does lightening occur when the thunder takes place in the atmosphere of earth?

Earth is supposed to be zero potential. Above earth surface, there is a vast atmosphere where there is flow of air. Whenever air moves nearby the ground, friction gets raised and electric charge is induced in the air. When there is loss of negative charge particle electron, air gets negatively charged. The same process goes on repeating. In a long run, air carries lots of negative charge in the form of the cloud. As we know there is always attraction between the negative and positive charge. We know the ground acts as a zero potential. Whenever the charge carrying cloud goes very near to the tall objects like tree or tower or hill, then the negative charge cloud induces the positive charge at the top of tall object. Slowly, there is attraction. As a result, negative charge come in contact with the positive charge and tremendous friction takes place. At the moment, great sound is produced which we call thunder and the electrical energy get changed into the heat and light. Since the light travels at very high speed, we see first light and only then the sound. We have so many misconceptions about the thunder and lightning. People think that the axe gets fell during the lightening which is not a fact. Actually, there is a flow of electric charge towards the ground with a very high speed and gets terminate at the zero potential of earth. We have developed the earthing so as to save our life from the dangerous situation of lightning and thunder.