The weather algorithm post this morning neglected any information about lightning. Since that isn’t part of the weather model analysis my partner and I are doing for our probability class, I haven’t developed it at all yet, but with that project starting to clear up, I’m more willing to move to other things.
The rules of how lightning works (the natural kind, not the direct magical sort as in Chain Lightning) are relevant to the Storm Caller from Monday, and will also be vital for tomorrow’s spell, Coax Lightning.
Mind Weave lightning is governed by a level of charge difference, or “Potential”, between the sky and the ground. This “Potential”, P, increases naturally over time as a function of wind and cloud cover but can decline if these components are not present. It can also be increased magically. The Storm Caller could increase the potential through its shout. Similarly, a caster with advanced master of the Des arc and the Neta radius can increase the potential. Each Des arc adds 10*1d6 potential to the atmosphere nearby.
The occurrence of a lightning strike in a given cell is determined using an exponential random variable with a rate lambda=(P/100)^2 per hour. Since lightning is an instantaneous event, the random variable uses time steps of 2 seconds with a rate lambda=((P/100)^2)/1800.
When lightning does strike, it expends E potential, where E is determined using 3d4*5. The bolt deals (E/5)d6 damage at the point of striking and does AoE damage as if with 4 DoP of Chaos (Indirect).
The point of impact is determined with a uniform random distribution over the area of the cell, but if the lightning is occurring shortly after an unnatural force has increased the potential, the Master Weaver can choose to have the point rechosen with emphasis on the area surrounding the source of the unnatural increase.
For an example of how effective a spell increasing potential can be, check out tomorrow’s spell, Coax Lightning.