Why doesn't lightning travel in a straight line?

Lightning tries to find the path of least resistance as it travels down to the ground.
Lightning tries to find the path of least resistance as it travels down to the ground. (AFP/Getty Images)
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This week's question comes from John Rathier in Ottawa, who asks 'why doesn't lightning travel in a straight line?'

Here's Dr. Gerhard Reuter, professor of atmospheric science at the University of Alberta's answer:

Lighting is an electric current. It's a flow of electrons that's about a thousand times stronger than the current in our houses. Lightning basically tries to find the path of least resistance as it travels down to the ground.  But this is not always a straight line because air is not a perfect mixture. There are fluctuations in temperature, humidity, pollutants, dust particles, etc. in the air, and so the resistance varies. As a result, lightning strikes are often observed in a zigzag pattern.