Lightning is formed like this. Thunderclouds grow and become highly charged. The uppermost layer accumulates more positively charged ions, while the lower layers accumulate more negative ions. When the charges are separated, an electric field is formed, and the air acts as a buffer separating negative and positive ions. When the charge becomes stronger, it overcomes the insulator, forming lightning either in the cloud (diffuse lightning), or outside (zigzag lightning).
However, a rare type of lightning called narrow bipolar impulse, much more powerful than normal lightning strikes, is created by a stream of positive charges. This type of lightning typically occurs when a charge strikes from the "positive" top of a thundercloud into negatively charged puddles on the ground.
By studying a narrow bipolar pulse, scientists at the New Mexico Institute of Mining and Technology (USA) found that the spark that “ignites” this type of lightning produces a “relatively unknown” discharge - a rapid positive decay. These sparks are very fast and travel at speeds up to 100 million m / s. They are also the most powerful source of radio research on Earth.
Scientists plan to find out how fast positive decays are formed, and how thunderclouds generate so much electrical current.