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					Lightning is produced because of a charge
separation in a cloud… The top of the cloud is
  positively
__________ charged and the bottom is
negatively charged. There are a couple of
__________
theories that attempt to explain why. (See article
or ACT practice question for the details.)
 The negative base of
                   e-s
 cloud INDUCES ____ on
 the ground to moveaway____
fromthe surface, leaving
 ____
    positive
 a ________ charge. We
 see lightning when e-s
 seek out positive charge
 in the air or ground.
If you are outside when
thunderstorms are in
the area, and you begin
to feel your hair stand
up (as did this woman),
WATCH out…. This is a
sign that the earth (and
you!) are getting
charged positively….
Lightning could strike
at any moment!
                Lightning Rods
Lightning rods are typically thin metal       ++
                                              ++
                                              ++
rods that protect against lightning           ++
                                              ++
                                              ++
damage by providing a safe pathway
to the ground for the lightning.
         +
Intense ___ charge builds up at the
tip of the rod, which can then help
initiate what’s called an upward-
traveling+streamer The downward
           _________.
traveling“stepped leader” is
           _______ ________
attracted to the streamer. WHEN they
                      e-s
contact each other, _____ travel
 down
______ through the channel formed
        lightning rod
to the ________ ____ and then into
                          Streamer that did
the ground.
                           NOT connect
      Some Basic Lightning “Facts”
                             1 inch
1. A typical “bolt” is about ______
  thick. We know this by analyzing
  “fulgurites”, sand that has been
  “fused” into a glass-like channel
  from the intense heat of lightning.
                                   5
2. Temperature is approximately ___ times hotter
  than the surface of the sun! Produces THUNDER!
         6000
3. About _____ bolts strike earth each minute.


                        -
4. Lightning is most likely crooked because
                 +
  “pockets” of ___ and ___ charge attract and
  deflect lightning bolt.
        Lightning Questions:
1. What should you do if you are outside in
an open area (like a golf course!) during a
thunderstorm?
             STAND UP
• DON’T _____________! (like a lightning rod…
tallest thing around)
            LIE DOWN
• DON’T ____________!
(Ground Current…
charge spreads out once
lightning hits the earth….
Cows are often killed
because of this!)
        Squat       Crouch
• DO _______ or ________!         Ground Current
2. Is it dangerous to be in a car that is hit by
lightning?
 NO                                  rubber tires
____! But, it’s NOT because of the _______ ______.
                                  outside
It’s because charge stays on the ________ of the
             ______
metal frame. (Recall that the electric field inside a
              zero
conductor is _____!)

3. There are many accounts of people living
through a lightning hit, both indirect and
direct! How could a person survive a direct
lightning strike?
It helps if the victim is wet Since wateris a better
                          ____!     _____
conductor than human flesh, e-s travel easier
through thewater “sheath”on outside of body.
              ______________
Smooth barked trees survive easier than oaks for the same reason!!
From "Lichtenberg Figures Due to a Lightning Strike"
by Yves Domart, MD, and Emmanuel Garet, MD,
New England Journal of Medicine, Volume 343:1536,
November 23, 2000
There are two main ways that people die from a
lightning strike: internal burns and heart stoppage.
So, being wet increases the likelihood that the
charge does NOT enter your body and cause
internal burns. IF the heart stops, only an electric
shock (defibrillator) can restore it.

4. A “rain gush” is sometimes observed at
the location of a lightning strike. What might
cause this?
Before the strike some water droplets are
                   electric field
suspended in the _________________ of the
_________
                                    field
cloud. When lightning strikes, the _______
strength is reduced, allowing the droplets to
fall.
Lightning
researchers, like
those in the next
video, trigger
lightning by firing
wire-trailing rockets
into a storm cloud,
giving the lightning
a pathway to
ground!

				
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posted:11/22/2012
language:English
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