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I am writing a sci-fi setting with space travel. In this there is an alien world important enough to require that I put thought into the ecosystem.

Unfortunately, due to plot reasons, the usual methods for advancing the nitrogen cycle aren't good enough, and to get more nitrogen oxides into the air, I need lightning.

A previous idea was to make lightning more frequent by lowering the voltage required to generate it, this does not work because low voltage lightning doesn't break apart nitrogen.

First, a summation of the planet. It is a planet warmer and a little smaller than earth but still in the habitable zone with a shallow ocean running around the equator and some ice at the poles. There are continents covered in various forms of flora and fauna. One of the continents is particularly mountainous, another one is more prehistoric with a dash of alien. Think how the world would look if all the plants had shiny stalks and dark leaves and there was no grass anywhere. The final continent has fungal lifeforms as the dominant form of stationary life.

How do I seriously up the amount of lightning planet-wide in a realistic way? I would like as plausible an answer as possible. Maths is useful but not required.

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    $\begingroup$ In the nitrogen cycle of this green Earth, "most [nitrogen] fixation is done by free-living or symbiotic bacteria known as diazotrophs" (Wikipedia). Lightning is a secondary and much less important mechanism for nitrogen fixation. $\endgroup$ – AlexP Aug 28 '17 at 16:17
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Building from scratch

weather.gov gives three cases where lightning can suddenly become more intense or common in an area:

  • "High instability" release: In this case, there is a large negative vertical temperature gradient (a.k.a. the lapse rate) in the atmosphere, i.e. temperature rapidly decreases with height. This induces a process called glaciation, which produces a difference in charge inside the cloud.
  • More moisture: More moisture means more instabilities, which in turn mean more updrafts and a larger charge differential when glaciation becomes more intense.
  • More wind shear: High winds again increase instabilities via turbulence; the usual process of glaciation takes care of the charge differences.

The temperature gradient on Earth is small in the troposphere, where most weather activity takes place. To change this, consider changing the composition of the atmosphere or the mass or size of the planet. The dry adiabatic lapse rate, $\Gamma_d$, is given by $$\Gamma_d=\frac{g}{c_p}$$ where $g$ is the acceleration due to gravity and $c_p$ is the specific heat. By lowering the magnitude of $c_p$ (which requires a change in the composition of the atmosphere) or increasing the magnitude of $g$ (which requires changing the mass or size of the planet), you can change the temperature gradient to make more lightning!

Looking at our world

On Earth, the region with the most lightning strikes per square kilometer per year is clearly central Africa (see Wikipedia for more data on the same subject):

enter image description here
Image in the public domain.

Why is this the case? The short answer is that it's due to a complicated set of factors. The slight longer answer is that mountains and air from the Atlantic Ocean make it easier for lightning to occur. Other mountainous regions with plenty of lightning include the Himalayas and the southern part of South America. Modeling your world after these regions could be a simple way to create more lightning.

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Dust storm lightning.

dust storm with lightning from https://photos.smugmug.com/Content/Stock/Landscapes/i-8LNTPGr/0/b5416494/L/BRH_7337-L.jpg

Dust storms make lightning. From reading about them, it looks like grain size and density make a big difference. You probably do not need to get into the weeds with this but you could have the dust on your world be optimal for generating lighting during storms.

Volcanic ash can make lightning storms. volcanic ash lightning storm from http://geology.com/articles/volcanic-lightning/

Maybe your world has ash fields that get stirred up and make these storms.

Best of all: ash dust devils. dust devil

Dust devils are cool because they seem like entities - they travel along, easy to see on a clear day. Not so much Hand of God stuff like a tornado, but more like some sort of monster. I can imagine the dust devil racing along over the ash bed, crackling with lightning. Things like that would be good natural hazards for your world too.

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    $\begingroup$ Dust Devils are really cool. They would happen out in the areas we played as kids in New Mexico. they spring up in random ways, move about in random seeming patterns, leave you feeling like you scuffed your feet across a massive length of carpet. Oh, and they will leave an amazing amount of dirt in a 12 year old's hair $\endgroup$ – Paul TIKI Aug 28 '17 at 18:24
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You can tweak parts of your world to have piezoelectric sparks

Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress.

Many materials, both natural and synthetic, exhibit piezoelectricity. Among the naturally occurring materials:

  • Quartz
  • Berlinite (AlPO4), a rare phosphate mineral that is structurally identical to quartz
  • Sucrose (table sugar)
  • Rochelle salt
  • Topaz
  • Tourmaline-group minerals
  • Lead titanate (PbTiO3).
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