There is an old saying about like objects repel and unlike objects attract. Remember this, as it is important when we are discussing lightning. Of course you can't discuss lightning without talking about thunderstorms in general. As a cumulus clouds builds toward a towering cumulus and then a cumulonimbus cloud (a thunderstorm), electrical charges build up in a storm. Ice that forms in the upper part of a thunderstorm creates a positive charge in that part of the cloud. Meanwhile, negatively charged particles tend to pool in the lower levels of the storm cloud. As a storm intensifies, more positively charged particles are found in the upper part of the cloud and more negative charges are found in the lower part. Because air is not a good conductor of electricity, these different camps of charges continue to grow and grow. Nature loves a balance and does not like all the positive charge being in the top part of the cloud and all the negative being at the bottom so it seeks to equalize these charges. As the difference between the positive and negatives becomes great so does the attraction. Eventually this attraction overwhelms the resistance in the air and nature strikes a balance. How? By lightning of course. The most common type of lightning is intra cloud lightning or that lightning that occurs within the cloud itself between the positive top and the negative base. So far so good? Now it gets difficult.
The large negative charge at the base of the cloud also acts like a magnet drawing a positive change up from the ground (here’s that attraction thing again). The negative charges send out feelers downwards called stepped leader that actually glow but very faintly. The positive charge sends up invisible streamers but their affects can sometimes be seen and even felt. The stories of somebody's hair standing on end before being hit by lightning are true. That's the effect that the positive charge streamer has on you as it starts flowing up from the ground, using you to help reach the stepped leader coming down. Should you ever experience such a thing, you may be about to be struck by lightning. Quickly get as low to the ground as you can without lying on the ground.
When one of the stepped leaders coming from the cloud contacts one of the streamers coming from the ground, a path is established and a current starts to flow. This path may be no wider than a pencil but the exchange of charge from cloud to ground and back again makes that path glow with extreme heat. Temperatures in the column of superheated air reach 50,000 degrees, which is 5 times hotter than the surface of the sun. That superheated air expands so quickly that it creates a shock wave (a sonic boom) that we know as thunder.
If there is any residual charge left after the initial stroke this whole process may be repeated within a fraction of a second making the lightning bolt appear to flicker. This entire episode may take place within 1 to 2 seconds. One last thing, while lightning originates from the cloud the luminescent bolt of lightning goes from ground to cloud.
All of that for one bolt of lightning. So the next time a storm rolls through this area you’ll know that there is a lot more going on then meets the eye. Respect the power of nature and take shelter. Lightning kills about 100 people and injuries more than 200 a year in this country.