# Does an object's movement affect the likelihood of being struck by lightning?

Does the state of whether an object if moving or stationary affect the likelihood of it being struck by lightning?

I suppose some things that could be considered would be:

Whether the movement means the object is not continually earthed, for example, a horse galloping across an open plain, during the gait there are moments when none of the horses hooves touch the ground.

Whether the movement affects the static charge of the object and whether this charge would be sufficient to affect the likelihood of attracting lightning strike.

Disclaimer

These are examples and limited, I am not interested in my own personal safety during a lightning storm, it is a scientific question. If we could move a large conductor are great speed (light and airplane), but on the ground, it would be interesting to see the results.

Here is a model that pictures the electrostatics of the creation of a lightning bolt.

The usual cloud-to- ground discharge probably begins as a local discharge between the small pocket of positive charge at the base of the cloud (the p region) and the primary region of negative charge (the N region) above it. This local discharge frees electrons in the N-region that previously had been attached to water or ice particles. These electrons overrun the p-region, neutralize its small positive charge, and then continue on their trip to the ground.

The horizontal extent is kilometers thus the field is built up from the ground, and there is no possibility of running out of the area. It is a matter of probabilities of the square meter or so where most of the energy will be dissipated and that depends on the local field distributions. A conductor like a lightning rod has a sharp field around it and provides the easiest path, if the strike were to happen within some meters of its location: strikes have a limited area, about 20 feet variability.

A horse or a human may find themselves in the strikes path, there will be little difference except on the conductivity of the body, I have heard of lightning just burning the clothes. If the horse is with four feet in the air, again it is a matter of the random path of the strike and the conductivity of the horse.

All in all it is the large geography of the spot that will determine the region where the bolt will strike and the local conductivities for the details. Running would help if one entered a house or other solid shelter. Falling on the ground or sheltering at a ridge is good advice to lessen the probability of being struck, because of the electric fields built up around high points: do not become the lightning rod by being the highest point in the region.

• @jinawee Maybe you are thinking of ball lightning? link.springer.com/article/10.1007/BF01055678#page-1 . An air flow within a hurricane or around a volcano where there is a lot of dust might carry/generate static charges and then this will affect the path of the strike esdtile.com/content/does-airflow-create-static-electricity – anna v Nov 15 '13 at 15:47
• No, Spain. I've found this claim: Don't run, specially with wet clothes. We create a turbulence and a convection zone which can attract the ray It's from an alpinism web, but it might be just a mith. – jinawee Nov 15 '13 at 16:05
• well, alpinism is on snow? I do not know the physics of rubbing snow ! Might generate static electricity ( the way the ice crystals in the cloud). It would not be the air flow but the friction from the feet on the snow. I used to be a runner when young and never noticed any static electricity under usual conditions. – anna v Nov 15 '13 at 16:20
• @Skippy : Maybe off-topic, but a known protection for a human is, to minimize the electric gradient, and to do that, you have to narrow at most the distance between your feet. – Trimok Nov 15 '13 at 18:12
• @jinawee That sounds very much like a myth - the atmosphere is already quite turbulent during storms, and, unless you run at many hundreds of kilometers per hour, there is no measurable effect on nearby air pressure. – user10851 Nov 15 '13 at 18:29

The advice I've read in some safety brochures suggests the answer could be "yes", but not the way you think. Lighting consists of both an "up" and a "down" stroke, and depends on a buildup of charge forming an ionized pathway thru the atmosphere. In principle (according to the literature), you might feel a slight charge buildup before the back-strike, and if you dive to the ground and flatten yourself, you may be able to pull yourself out of the conductive path.

Edit - consider some of the info here: http://science.howstuffworks.com/nature/natural-disasters/lightning3.htm . And here's some stuff from a backpacking site, whichmay or may not be accurate.

"Positive Streamers? You’re About to be Struck.

Being struck by lightning is often preceded by a sensation of tingling
If you have this feeling and are in or near a lightning storm, your body
has likely sent a positive streamer.
If this sudden charge connects with the electrons pooling beneath the
storm clouds, lightning will strike.
If you feel this sensation, either run as fast as you can to shelter
or immediately crouch on the balls of your feet (follow the guidelines above).
Hold your breath, as you can breathe in the superheated air that
surrounds you and is expanding out from a lightning bolt."

• This is not making sense to me.. I'm a but confused about what you are saying (thnx for answering though :) – user110352 Nov 15 '13 at 12:57

I don't have a complete (or even a definite) answer, but I am pretty sure the speed of the object affects the probability of lightning strike. My belief is based on the following: "Because many aircraft fly a distance equivalent to several times their own lengths during a lightning discharge, the location of the entry point can change as the discharge attaches to additional points aft of the initial entry point. The location of the exit points may also change." (http://flightsafety.org/aerosafety-world-magazine/june-2010/when-lightning-strikes )

• Yes I was going to ask about airplanes. It's a difficult question to answer, but I thought there may be a brainiac out there who knows :) – user110352 Nov 15 '13 at 15:29

I would expect that movement per se, simply changes the conditions (slightly), and it isn't possible to say that the probability of being hit, either increases or decreases. We have no "Maxwell's Demon" watching and waiting for some specific state of affairs to exist that will get us hit.

But as to the horse either touching the ground or not, there isn't any difference. Afoot of air under the hooves is going to replace a lost foot of air above the horse, and the total path resistance is unchanged. But if on the ground in the open, the usual wisdom is to curl up into as compact a bundle as possible. In elementary electrostatics problems, this arrangement is usually described as: "A hemispherical boss on an infinite conducting plane." The presumption being that one should maximize the minimum surface curvature, to reduce the local field. Assuming this thesis is true, not too many of us would think to use clothing, or blanket like items to form an "igloo" dome over ourselves, to further increase the radius. When wet, such materials would be nearly as good as metals.