How we handle Lightning and Electricity
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As I was trying to come up with solid guidelines for Smash Bracket, I realized that it’s very difficult to find studies that compare lightning across large periods of times and in multiple environments. Most studies were focused in one small region over a short period of time, had small sample sizes, and had a huge range in the data they collected. As I was working to compile all the studies on lightning I could find to try and see how significant the variance was between studies, I found that many of the studies referenced a textbook, and that textbook has done the work for me of compiling decades of studies from all across the world. So while I have looked at quite a few studies outside this book, I will be basing most of my information from Lightning Physics and Effects. Check that if you would like to verify any information or sources
What determines the speed of electricity through the air
This question is deceptively hard to answer, mostly because what we see when electricity arcs isn’t actually electricity, but plasma that results from the air being ionized and heated up. The electricity moves extremely fast, at a significant portion of the speed of light, but it will take frequent breaks as it travels. The visual part of the arc is also probably lagging behind a bit, since it takes a relatively long time to heat the air enough for it to become a plasma. What this means is that the overall speed of an arc is more influenced by the frequency and duration of the pauses the arc takes than anything else. This is also why electricity always seems to zig-zag through the air: it jumps to one location, pauses, then jumps to another location and repeats.
From what I can tell, the process happening here is roughly as follows: some source of electricity accumulates charge until it has enough to meet the breakdown voltage required for a certain arc length. It then jumps, maintaining a channel for the electricity to flow through. The new head of the arc then accumulates charge until it can breakdown the air enough to jump, and this process repeats until the source can no longer provide enough charge quickly enough to make another jump. This is definitely a large simplification of the process, so forgive any imprecise terminologies.
What is important, to our purposes, is that the amount of voltage present in an arc determines how far it can jump in each discrete step. The overall power and current in an arc will help to determine how far it can move overall, but I don’t think that relationship is clear enough to be helpful here, especially since that would rely on information we’ll almost never see in fiction. But by knowing that speed is generally related to power and the distance of the steps is related to voltage, we are able to estimate the speed of an electrical discharge based on the distance of each step.
Caveats
This method is basically a speculative relationship between hard data. It is a useful tool for estimations, but it should be kept in mind that it really is only a very rough estimate. This holds especially true for ranges outside of what we see in natural lightning. As such, we should be especially cognizant of outliers when dealing with lightning, and even more so when dealing with short-range electrical attacks. The steps in lightning range anywhere from 10m-200m, but anything outside that range is going to be pretty dubious. This should basically be a last resort for determining speed outside of that range.
When is this applicable
As I alluded to earlier, the distance of the discrete steps in an arc is what is important, not the source. Natural lightning shouldn’t be treated differently than any other electric based attack: this will work for everything.
For dodging electricity, what is most important is determining the actual target of the arc. If we can’t see tandem movement with the arc, we need to be sure that it was actually targeting our character in order for lightning-dodging speed to be applicable. But if we are sure that it was targeting a character, then they will scale to the speed of the attack. This is because it’s impossible to “aim dodge” electricity, even if it was from a heavily telegraphed attack coming from another person. An electric arc is the result of a difference in electrical potential between two objects: this means that it’s not like a projectile being fired, but more like a channel being opened between two objects and then filled with the electricity. In order to actually dodge it, a character would have no option other than to react after the bolt starts. Of course, since a bolt can still “miss” by targeting the wrong object (like a nearby patch of ground), this is why it’s important to make sure of the target of the attack before we can apply this.
The speeds
Step Length - 200+ m: 3.9E6 m/s (mach 11,370) This is the highest value I could find natural lightning reliably attaining
Step Length - 150-200 m: 1E6 m/s (mach 2,915) This is the high end for most ranges of natural lightning. It can be faster, but usually isn’t.
Step Length - 100-150 m: 2E5 m/s (mach 583) This is the typical average speed of natural lightning
Step Length - 50-100 m: 1E5 m/s (mach 291) This is the low end for most ranges of natural lightning. It can be slower, but usually isn’t
Step Length - 10-50 m: 3E4 m/s (mach 87.46) This is the lowest value I could find natural lightning reliably attaining
These last two values are based on some measurements that I found for a tesla coil gun. Notably, the ranges that I’m giving for the step length here are completely arbitrary. This is the slowest I’ve ever seen electricity arc through the air, so I wanted to use it as a low end, but there’s a pretty big range in these measurements and it doesn’t fit super well into the system we use for lightning values. We’ll probably never use these if there is any other method for determining the speed of the arc, but I figured they would be useful to include just in case.
Step Length - 1-10 m: 4000 m/s (mach 11.7)
Step Length - less than 1 m: 556 m/s (mach 1.6)
Modifiers to speed
There are a few signs that natural lightning is moving faster than its stated speed above. Each of these will act as a modifier for the speed of the lightning that we see.
Tandem movement with the bolt when it is near the ground. Lightning speeds up when it is close to the ground, up to 6x faster.
Multiple strikes. Most lightning actually strikes the same spot many times. It can hit slightly different areas, but subsequent bolts will travel down the same path as the first. These are call dart leaders and they move at 2E7 m/s, mach 58,309, or 0.07 C. Dart leaders don’t reliably speed up when they get near the ground, so don’t use the multiplier for tandem movement near the ground with them. There needs to be less than a second between these strikes (usually much less) and we need to be sure that the subsequent bolts are following the same channel.
Return Stroke. What we usually associate with lightning is called the lightning leader. It moves downward from a cloud, “searching” for a target. When it connects to one, the “real” lightning moves upward from the target to the clouds. That is called the return stroke and it moves at about 30% the speed of light. For this to be usable in a feat, we would need to see the leader move downwards, strike, and then see the return stroke moving back up.
Duration of Lightning
Something I’ve attempted to do in the past is figure out how fast someone is moving based on how long they cause a lightning bolt to remain visible, since usually the ground flash only sticks around for a short amount of time. The range in duration for lightning bolts turns out to actually be very large though, with typical values being anywhere from 10 milliseconds to 2 seconds. Positive lightning can stick around even longer, but I don’t have good data on exactly how much longer. We’ll use 2 seconds as our assumption for any feat that is based around making lightning stick around longer than usual unless we have some more specific timeframe given.
