The mechanical force of lightning?

[Kedas]

This morning I woke up wondering: Where does the force come from that splits trees in two and can 'blow' poeple away.

 

-about the tree:

The tree is an conductor and the gas of water creates the pressure that causes the damage. But why nicely split up, shouldn't the whole tree have equal damage? (current spread over the full diameter of the trunk)

maybe some electromagnetical forces?

 

-about the body: (not necessary lightning)

The muscles of the body are triggered and you are actually throwing yourself away? and some help from wind due to the heated air?

 

any more thoughts?

[YT2095]

the voltages in a lightening strike are so high and fast, that the energy doesn`t actualy penetrate us to our core, it stays on our surface (called Skin Effect).

as for the trees, on a cross section they run in concentric circles, making them an ordered patern, the blast will therefore go WITH the grain of the wood being as it`s the path of least resistance to the gas that trying to escape, a similar thing happens with explosive charges when "tree stumpin`", if you drill a hole in the trunk and place your charge in it, it will split the tree top to botom rather than lateraly

that`s why strategic cuts have to be made before this to get the desired effect

[Dave]

It's quite amazing that something that is effectively electricity can generate enough force to throw you 10 feet away, or power an entire city for about a day.

[YT2095]

yeah!

Nature is certainly a force to be reconed with, Underestimate her at your peril!

[Kedas]

yeah!

Nature is certainly a force to be reconed with' date=' Underestimate her at your peril![/quote']

 

So you don't include yourself in the nature part?

 

Why doesn't the ?shell? fly of. (if we assume that current doesn't flow in the centre?

[greg1917]

"I think the main idea is that air masses develop a large charge through some process we don't fully understand. This probably involves frictional contact between water droplets which leads to charge segregation inside the cloud. When the potential difference between the cloud and the ground exceeds the break-down potential of the atmosphere, a tongue of negatively-charged particles invisibly descends from the cloud to the ground in a path of least resistance until contact with the ground is made within a few seconds. As soon as this happens, a massive flow of electrons travels down the channel in several pulses, to form the lightning bolt. This bolt is a channel perhaps a few centimeters wide, but where frictional energy heats the air to nearly 10,000 degrees. There are thousands of these bolts of lighting going off every minute around the world, and this helps keep the atmosphere at a fixed voltage relative to the ground of about 250 volts or so. "

 

Directly lifted from:

http://image.gsfc.nasa.gov/poetry/ask/a11788.html

[Sayonara]

With respect to trees, the force comes from the sudden expansion of super-heated vapour when the lightning instantly boils the sap.

[Kedas]

anyone that can contribute to my question? (instead of repeating)

 

YT, why not only the shell?

[YT2095]

the outer shell on a tree is largely inactive in the way of growth, most of the moisture content is on the inside, that`s NOT to say that the "outer shell" or Bark is not alive, it is very much so!, but lacks the majority of the water content.

that will be in the very center from the "tap root" ready to make a new ring for that year, that`s what has the most water and ionic nutrients N-P-K and is highly conductive as opposed to the slower growing that contains "sap" and is largely hydrocarbons that don`t conduct anywhere near as well

[Sayonara]

See, the living material that makes up the trunk of the tree is near the 'core' - the rings are really separate layers of columns of dead xylem and phloem vessels. The trunk grows from the "inside", as it were, and older material is always nearest to the bark.

 

When the lightning hits the tree, it superheats the living matter which explodes violently, "bursting" the outer layers open.

[Glider]

The 'living' material of a tree (the cambium) is the outermost layer between the heartwood and the bark. The centre of the tree (heartwood) is dead and provides structural support. The xylem (just inside the cambium) consists mainly of tubules which carry water and minerals up the tree. The phloem (just outside the cambium) carries food (sugars) both up and down the tree. The cambium layer (which also stores sugars) is constantly growing and dividing, and as the trunk expands, the inner, older part of the cambium becomes the xylem, the newer outer part of the cambium becomes the new phloem (inner bark). As the tree grows, the old xylem lignifies to become heartwood, and the old phloem becomes bark.

 

Amazingly, the cambium layer, even in the biggest trees, is a single cell layer, a bit like a 'living skin', but excluding root-tips and leaves, it is the only living part of a tree.

 

I knew that bonsai training would come in handy

[Sayonara]

Argh, I got it backwards. How embarassing.

[YT2095]

I think it was all this talk about "outer shell" that made it confusing, as there`s no such term with regard to trees, so we all had interpret it our own way

[Kedas]

I think it was all this talk about "outer shell" that made it confusing, as there`s no such term with regard to trees, so we all had interpret it our own way

Yeah right

 

So we can assume that most of the sap is located at the outer layers? (not shell )

 

I did try to find some photo's

http://www.weather-photography.com/Photos/gallery.php?cat=lightning&subcat=trees

http://www.weather-photography.com/Photos/photo.php?cat=lightning&id=w-191-31

outer layer is blown of

 

any idea's why it's only one side?

 

Edit:

look at this one, a nice line at the edge. (oops, I mean outer layer)

http://www.erh.noaa.gov/gsp/pictures/lightning3.gif

[YT2095]

yup

 

the sap`s not very conductive, as I said it`s mainly hydrocarbons (that`s how we get rubber by cuuting into the outside of the tree, or maple syrup etc...)

the water carying part is though.

 

cool pics!

the bark coming off wasn`t disputed anywhere?

[Kedas]

the bark coming off wasn`t disputed anywhere?

No, I did assume that it did split in two.

(I saw too much cartoons I quess )

[YT2095]

well you`re not entirely wrong in your assumption, some trees do! some you can`t even tell they`ve been hit untill you cut them down, for example there`s a tree just over the road from me that was well over 100 year old, it was cut down

but right through the center of it, it was burned out and hollow! the hole was about 8 inches across in places and all chared, and yet before it was cut down, it looked and grew quite normaly.

so it`s not really possible to say that a tree when hit will react in a certain way, some will split, some will burn, some will lose layers, there`s alsorts that can happen really