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.