Electricity

The lightning strikes animation above shows;

1. From cloud to ground - The violent movement of air within the storm produces a huge electrical charge on the cloud. Eventually the potential difference (voltage) between the cloud and the ground is SO high, that the AIR becomes a conductor. The electrical discharge (the lightning bolt) seeks the path of lowest resistance and is attracted to the highest points that conduct electricity best.

2. A combination of a ground to cloud and cloud to ground discharges.

3. This is a continuation of 2 but for the charges to move through the air, the air must be a conductor. As a result of this the air becomes superheated giving rise to the release of energy as the intense flash of light and the 'thunder clap'. You can notice the bolt of lightning hitting the Southern tower of the Harbour bridge.

4. The final image shows mainly a cloud to cloud discharge, but you can also see the lightning flashes travelling to large metallic objects on the ground, e.g. the Harbour bridge.