>We all have discussed the resistance of air.  When you pass current throught
>a wire, it heats up due to joule heating.
	Yup.  Mostly.  There are some alloys that decrease in resistance when

>Place more resistance, and the wire gets hotter.
	Dpendson the voltage sourec and its capability.  If its a fixed voltage,
	adding resistance decreases, current, decreasing power disipated,
	decreasing heat/temperature.

>The air around a Tesla coil or lightning bolt acts as the wire.
	Ionized gasses, including the mix we call air have interesting
	properties.  They conduct once theya re ionized.  They ionize (for
	one) as they heat, getting more ionized as the heat more.  This means
	that for most arcs and sparks the resistance DECREASES as the Current
	INCREASES and, in fact, an arc demonstrates negative resistance.

>With all that voltage and current flowing thorugh the air, the result is and
>explosive expansion of the gas as it heats up.  This is what causes the
>repercusions of sound waves.