I've been looking online for a forum post, website article or indeed a physics stack exchange question that could help me understand why electric arcs form. I've seen plenty regarding the flow of electrons in an arc, their speed, the length of the arc etc. but, to the best of my ability, I was not able to find WHY an electric arc forms.
Normally, air is rather non-conductive yet if you have enough electric potential difference between two electrodes, the air becomes conductive. Why? What is it about this large voltage that causes the air to become conductive?
I read that when the voltage exceeds the break-down voltage of the medium, air in this case, it becomes a plasma and starts conducting. How does this occur?
Do the air molecules, or perhaps their constituents (atoms, electrons...), align themselves in such a way that they start to conduct? If so, what force acts upon them to behave as such? Is the air subject to an electric field that causes this to happen? If no current is yet flowing between the electrodes how can there be an electric field?