The ocean covers a good 3/4s of our planet’s surface.
Salt water is a good electrical conductor.
When lightning strikes somewhere on Earth, logically, a high probability will be the surface if oceanwater.
How does a lightning bolt transverse the distance of the ocean from the surface to “ground”?
The water is ground, electrically.
Yes and salty seawater is almost always a better ground (more conductive) than any other practical natural surface. There’s a joke in shortwave & ham radio about ‘10dB gain when beachside’ which is way too much but certainly there’s some radio advantages to more conductive grounds.
Lightning couples to the surface of the sea really quickly and, compared to a tree or skyscraper, over quite a large area with effectively infinite volume below it. It’s not quite as good as a block of copper but way better than most dry land.
Are fish affected by lightning strikes if in close proximity? How close?
Generally not. The lightning typically discharges along the surface. How deep the charge gets, we don’t really know, but generally unless a fish is swimming right at the surface or jumping into the air as the lightning strikes, they won’t be affected.
This was basically my concern: there must be some critical distance to lightning striking the ocean for the various marine life in proximity to the strike.
What if the marine life in question is an electric eel?
I just read up on it, if they are close to the surface and in close proximity it might kill them.
Same is true for humans, a lightning strike in close proximity can badly injure or kill a person.
e.g.:
[Moderator Note - link spoilered since it involves the death of a soccer player]
When lightning hits the ocean, it spreads out in all directions. It remains lethal out to probably somewhere around 50 to 100 yards in all directions, getting weaker the further you go from the point of the strike (in other words, at 10 yards you’re probably toast, at 100 yards you have a decent chance of survival but a non-zero chance of death).
Electric eels produce low-level shocks and high level shocks. At the highest level, the shock actually hurts the eel a bit too. The high level shock is typically somewhere around 600 volts and contains maybe a couple hundred joules of energy.
A typical lightning bolt is somewhere in the range of several hundred million volts and contains several billion joules of energy.
The eel is toast.
Electric eels are solely freshwater.
Well, mostly in the ‘away’ directions and a lot of that will ultimately dissipate ‘down.’ I think most of the current will be along the surface so an intensity graph (a zap map, lol) would more closely resemble a disk than a hemisphere.
People sometimes dig up the glassy fused sand after beach strikes but it’s unclear how wet the sand is or similar it is to open ocean.
The only “zap map” (heh, I like that term) I’ve ever seen looked more hemispherical. I have no idea what data, if any, was used to make it look like that or if it was just someone’s guess.
For those who aren’t familiar with it, the term to google is “Fulgurite”. In my admittedly limited experience, they tend to go down into the sand as well as spreading out below the surface.
It’s a lot more dangerous for quadrupeds, though. The biggest danger from a near-miss is what’s called “ground lightning”: The current has already reached the ground, and is now going through the ground. If you have one foot six feet closer to the strike point than the other, that gives the current a six-foot-long path that’s probably less total resistance than the ground, and so it’ll mostly flow through you. If your feet are only six inches apart, though, the advantage to the current going through you instead of dirt is much lower, and so a much lower proportion will go through you.
But we’re talking about creatures in open water, so I don’t think that applies.
Why do you think the current would radiate preferentially along the surface of the water rather than dissipating radially in all directions (horizontal, vertical, and every direction in between) through the water?
So standing on one foot during a lightning strike is the safest stance?
Depends on the relative risks of ground lightning versus losing balance and hitting your head, I suppose. Usually crouching (on both feet) is recommended.
I have heard stories (which may well be just that) of a lightning strike in a field killing those animals that faced on axis to the strike, and spared those animals that stood perpendicular to the strike.
In principle the ground is a large distributed potential divider. The further apart two points are, the higher the potential between them. So two feet close together good, four feet far apart bad.
As far as strikes at sea go, this very short video gets about as close as you would ever want to be. Only a single strike, best visible at the 0:05 second mark. Video includes the on-board reactions and multiple views. These boats are essentially 100% carbon fibre, with a bit of high tensile steel where needed. A strike on one would make the word catastrophic seem inadequate. One boat just high tailed it straight inshore, ceding the race on the spot. Race was cancelled shortly after anyway.