-    -   -   -   -    -   -   -   -   -   -                                                     - - -
        Strong negative charges          - -
           build under clouds           -
                                       -
                                       --
                                        -    Negatively charged particles, 
                                         -  called the stepped leader, move 
                                         -        toward the ground
                                         -                    
                                        - 
     When the stepped leader gets       +   
  close to the ground, a positively     + 
  charged stream travels up to meet     +
    the negative creating a strong      +    
    electrical current - lightning!    +
                                       + 
                                       + 
                                        +  Strong positive charge builds up
                                        +     on the ground below the cloud.
                                         + It stays under the cloud as it moves.
                                         +  
                           +   +   +   +   +   +   +   +   +   +   +   +