Lightning Strike Probability
Recently I came back from India and experienced how sever
a thunderstorm can get. In my experience I saw lightning strike in
my backyard twice around the same area. Now asking around I found
out that it's quite common of an occurrence that lightning strikes
our backyard. Now I was wondering what kind of factors affect if
lightning will strike the ground or not? Do minerals in the soil
play any role?
Lightning can strike the same location more than once
and in some cases can do so frequently. A good example
is that isolated tall objects (such as towers, tall hills,
tall trees) can be struck frequently, primarily because
as the tallest object around, electrical charge can most
easily accumulate on them. Charge also accumulates most easily
on more pointed, as opposed to blunt or flat, objects.
For this reason, a hilltop is not a good choice for a home
if lightning occurs frequently in the area.
In the same way, if your backyard is at a higher elevation
than the surrounding area, it may be a prime location for
a lightning strike.
The mineral content of the soil may or may not have an effect,
although a high metal content may allow the soil to better act
as a ground, bleeding off electrical charge and reducing the
likelihood of a lightning strike. Your backyard apparently
does not have a high metal content in the soil.
It is not clear why lightning strikes the ground as opposed to
a tall object nearby. This happened to one of my neighbors
when lightning struck in their backyard instead of nearby
trees or their chimney. For some reason, more charge built up in
the backyard than on nearby tall objects, from which a stepped
leader reached up towards the leader coming down from the
thunderstorm cloud; upon connection, a lightning strike occurred.
David R. Cook
Climate Research Section
Environmental Science Division
Argonne National Laboratory
There are several factors determining where lightning will strike.
Is your back yard a high point compared to the surrounding area?
Does it have tall trees or single tress widely spaced?
Also, is the soil sandy and prone to being wet or saturated when it rains?
All these things can contribute to repeated lightning strikes. Some man-made
structures can also attract lightning, but I assume you do not have a radio tower
or the like in your back yard.
Hope this helps.
R. W. "Bob" Avakian
Oklahoma State Univ. Inst. of Technology
Click here to return to the Weather Archives
Update: June 2012