Why Do High Energy Discharges Arc?

[peter.ell]

I'm interested in understanding why high energy discharges arc rather than just travel in a more direct straight path.

Thanks for the enlightenment.

 

[FireStorm000]

Ionized air in an arc rises because it is hot from joule heating. I'm not entirely certain why the air glows though. In short, it's not about the shortest path, but the least resistive one, so if the conductive medium rises due to convection, then the electricity will follow.

 

[Drakkith]

Per here: http://en.wikipedia.org/wiki/Electric_arc

The various shapes of electric arc are emergent properties of nonlinear patterns of current and electric field. The arc occurs in the gas-filled space between two conductive electrodes (often made of tungsten or carbon) and it results in a very high temperature, capable of melting or vaporizing most materials.

When air is ionized, the particles don't simply stay stationary. They have very high energy and move around. I'd also guess more non-ionized air probably moves in and around the ionized air and contributes to drift and other effects.