Evolution of the lightning stroke

• as the area of negative charge builds up near the base of the cloud, it induces an area of positive charge at the ground - opposite signed charges attract each other
• the negative charges in the base of the cloud and the positive charges at the ground create a potential difference, or a voltage, just like a battery.
• once the voltage reaches a critical strength, the atmosphere tries to reduce it.
  • first, a stepped leader is created at the base of the cloud
    • the stepped leader is a channel through which electrons in the cloud can travel to the ground
    • the stepped leader is invisible to the eye
    • it travels discretely to the ground, 50-100 meters at a time
    • it then stops for about 50 microseconds, then travels another 50-100 meters.