By DAN ROBINSON Storm Highway Editor/Cameraman

Why doesn't lightning travel in a straight line?

Do this simple experiment: Take a bucket of water outside. Find a mound of dirt or sand or a hill covered in rocks and dirt. Take your bucket of water and pour it out at the top of the mound or hillside. What happens?

The water takes a more or less jagged path down the hill as it meets things like rocks, clumps of dirt, or variations in the surface of the slope. The water, pulled downhill by gravity, is taking the path of least resistance to the bottom.

Although we can't see it, air is made up of all sorts of different gases, elements, particles, moisture and the like. As a result, air is a lot like that dirt- irregular and uneven.

When a lightning channel begins to form, pulled along by the difference in electrical charges, it takes the path of least resistance through the air- very much like the water flowing down a rocky hill.

The result? The 'zig-zagged' shaped lightning we see: