Lightning safety: under trees or in the open?

General Questions
#1

I have just read through a few threads on thunderstowms and lightning, and I checked out the following referenced link:

But I still have the following question. I spend a lot of time hiking in the low mountains near where I live and occasionally am caught in lightning storms. Now the web link tells us what to do if you are caught in a wide open space, and if you are caught within a forest, but what is best to do if you have a choice between the two, as is often the case where I hike? Is it better to stay in the open and crouch down as they describe, or it is better to run into the forest under a stand of trees of similar height?

And a variation on this: which is safer, crouching in the open, or taking shelter under a single tree, also in the open? In the former, although crouching, I would still be the tallest thing around. If I go under the single tree, I am no longer the tallest thing, the tree is… Which is better?

#2

Broadly speaking, lightning will follow the path of least resistance to ground; when you’re standing upright in the open, your body is a path of less resistance than the air around you, however, the lightning won’t skip sideways half a mile (traversing a greater distance through high-resistance air) to strike you.

As you approach a tall tree, there will be a point where [tree+air above tree] offers less resistance than [you+more air above you], but as you get close to the tree, there’s a break-even point where [air above tree+part of tree+air gap+you] becomes a path of lower resistance than [air above tree+tree] - at this point, there is a danger than lightning will strike the tree, then arc across to your body to get to ground. (Given that, generally speaking, your wet, salty body is a better conductor than the same amount of woody, slightly moist tree).

The best thing to do is head for lower ground, avoiding ridges and peaks, also avoiding close proximity with lone trees.

#3

From here:

Yesterday I pulled the first aid kit out of the Jeep to see if there was some ibuprofen in it for a co-worker. I happened to flip through the little booklet, and it talked about a “cone of safety”. It said to stay within a 45º angle from the top of a tall tree; not too close to the tree, and not to close to the edge. It also advised crouching down, only your feet touching the ground. But as the weatherwise site says, it’s not fail-safe.

#4

That sounds plausible - the reason it isn’t fail-safe, of course, is that a)the most direct path to ground might be nearer you than the tree and b)if it is raining, a particularly dense drift (there’s probably a proper term for regions of inequal distribution of falling raindrops) of rain could (temporarily)significantly lower the effective resistance in the path that just happens to include you.

#5

When I lived in Arizona (one of the places in the US with the most Lightning strikes per year) I did a voracious amount of hiking. Everything from deep sonoran desert hiking (meaning out in the open, little to no cover) to upper platte forest hiking along the Mogollon Rim. Every so often, especially in the summer monsoon months, I’d get caught in a decent thunder storm.
Being a New Englander by native decent, I was not used to having to find cover from storms. As in New England, one can find cover or shelter very quickly. So being out in the open during one of these large cell storms was an awesome sight to behold. There reaches a point in every electric storm where you can feel the electricity in the air. Almost sense that the air is alive. The atmosphere becomes almost a purply hue and the air get’s heavy, you just know the lightning is coming. I’ve been hiking several times when this happens and it is a scary time.

During an outward bound class, where we spent a week in the desert at the end of the semester (I was a 2nd year grad student at the time) we learned proper lightning safety. And in the desert, it was find the lowest point you can, and find it quick. Also, be aware of your bodies reaction to the storm. If you feel your hair start to rise, crouch down on the balls of your feet as quick as you can, because there is a streamer lifting from your body, to connect with the lightning’s energy, the connection would be the strike.

As we all know, lightning strikes from the ground up, the streamer goes from your body, the top of a tree, or a blade of grass to try and connect with the energy being emited from the storm, when the connection is made the strike happens. Many times people do not even know it, and if they are lucky enough to survive they wake up 20 feel from where they thought they were standing, dazed an confused, with a hell of a head ache and some burning…

To answer the OP, I’d find the lowest place I could and crouch down. The main part of being under a tree that is bad, is not being struck by the lightning, but by the shrapnal from the tree exploding next to you. I’d probably stay away from the trees. Unless you are in a forest, in which case I’d again, find the lowest place to ride out the storm…

#6

I used to work at Lockheed at Ontario International Airport. Once during a storm I was walking to my car at the end of the day. My fingers touched the metal of my umbrella and I felt an electical current. Not a quick shock, but a sustained sensation of electricity. I knew about streamers, so I was a little nervous until I reached the safety of my “mobile Faraday cage”. :eek:

#7

Not much more to add, other than anecdotal confirmation. I was also a New Englander out west - spending two weeks in the mountains of Colorado and New Mexico. We were above the tree line a couple times, but usually shrouded by forest while in the high country. I don’t know if it is a regular weather event, but thunderstorms passed through in late afternoon about 75% percent of the days I was there. Spectacular storms, especially when you’re right in the thick of it with nothing more than a small nylon tent for shelter.

We were given the very same instructions: Try to find a low area, crouch down into a ball hugging your knees, and try to balance on your toes. Again, this reduced your contact area with the ground, and also made the shortest possible path through your body, should any stray voltage happen along.

Up in those hills, there were open areas as well as thick woods - and I always felt safest among the trees. I figure I’m surrounded by thousands of other lightning rods, so the chances of a direct hit are pretty slim. And despite being surrounded by positively deafening thunder and lightning a number of times, I never felt the tingle in my tootsies from any nearby strikes.

The great thing about lightning is that it never plays by any predictable rules. So just do what you can and hope for the best. It only kills about 100 people a year in this country - get out there and gamble a little!

#8

I understand (but I wouldn’t swear it’s accurate) that the safer spot would be crouching near a tall tree, at a distance close to but smaller than the tree height. Since I’m probably not very clear, if say the tree is 9 metres high, you should crouch at 7-8 meters away from the tree.

#9

Like Phlosphr, I am a Bounder too. Our course was in the Boundary Lakes of Canada, and we spent all out time canoeing. When a storm came up (most afternoons), our choice was clear, get off the water into the forest and squat on our lifejackets, or be pan-fried in our aluminum canoes. Not too many isolated trees to think about there…