How does lightning strikes?

Question

From what I've learned (maybe not much), lightning happens because there are two things that has two different charges...

And I thought that lightning was supposed to come from point A to point B, and in the process itself, it creates the line that we see . But from the animation http://wvlightning.com/cgdesc.shtml, the leaders actually come from both side...so...which one is right? And why?

Second...let's say...If a person has static electricity inside his body for 1 GV (I know he should probably be dead, but bear with me...) can he shoot a lightning bolt to an object about 5 m away? If so, what's the voltage running through the object?

And finally, what's the electrical breakdown voltage for air?

Answer 1

Lightning

happens when a cloud builds up a separation of charge. The bottom of the cloud

(facing the earth) has a negative charge (extra electrons) while the top of

the cloud expels positive charges up and out into the upper atmosphere.  So

the cloud has all this extra electrical energy on the side facing the earth,

and eventually it dumps the energy down towards the earth, which tends to have

a positive charge (for complex reasons) compared to the cloud's underbelly.  

When the stroke begins, a series of little pulses of electricity come down

from the cloud towards the earth at really high speeds (about 1/6 the speed of

light!).  These pulses are called steps, and the trail they pulse down along

is called the step leader. (not ladder).  The air gets ionized along the step

leader and so this column of air becomes a good conductor of electricity. So

when the step leader (which is so faint that it is practically invisible) hits

the earth, a "conducting wire" of air is set up from the cloud to the earth.  

Now charge can flow, but the first charges to move are the ones at the bottom

of the wire (near the earth).  So, the stroke (which is now visible) starts at

the bottom (the earth) and runs UPWARDS from the ground! This return stroke

produces the bright light and a lot of heat, which causes the air to expand

suddenly, which causes a thunderclap.  This sequence often repeats, which the

charge going up and down the leader.

Electrical breakdown in atmospheric air between closely spaced (0.2 /spl mu/m-40 /spl mu/m) electrical contacts.

The increasing importance of electrical contacts in air with micrometer spacing prompted recent experiments on the electrical breakdown behavior of these gaps. The electrical field between the contacts used in one of the experiments was analyzed using finite element analysis to model the electric field. The experimental data on the electrical breakdown voltage could be divided into three regions as a function of the gap spacing. First, at close gap spacing (/spl les/4 /spl mu/m) both the breakdown voltages as well as the electrical fields at the cathode were similar to values measured during the breakdown of vacuum gaps of less than 200 /spl mu/m. Second, at larger gaps (>6 /spl mu/m) the breakdown voltages followed Paschen's curve for the Townsend electron avalanche process in air. Finally, in between these two regions the breakdown values were below the expected values for purely vacuum breakdown or purely Townsend breakdown. The breakdown phenomena have been discussed in terms of field emission of electrons from the cathode and their effect on initiating the observed breakdown regimes.

Answer 2

Lightning can come from all directions.  From the cloud to the ground is the most noticed but it can also be incloud,  cloud to cloud, cloud to air,  just about any conceivable direction.