The earth experiences about 44,000 thunderstorms every
day, with approximately 1,800 storms in action at any given
moment. The most active area in the world is Java, an
island of Indonesia, with an average of 223 storm days per
year.
Florida is known as the lightning capital of the United
States, with storms occurring approximately 100 days out of
the year, compared to California's low of only 5.
Although our entire state rates as a high risk area, the
most dangerous area runs from St. Augustine (north) to Lake
Okeechobee (south) and from east to west coasts. That
puts our Tampa Bay area right in the middle of the danger
zone. Daily summertime showers are a fact of life in
Florida but should not be taken for granted.
Florida ranks number one in the number of deaths due to
lightning, 94% of which occur between late May and end of
September. An average of 100 people are killed in
the U.S. each year (10-13 in Florida) and almost 600 injured
(30 in Florida). Lightning kills more people in the
U.S. than hurricanes and tornados combined.
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| WHY FLORIDA? Partially due to its high heat
levels, high humidity, and location between the Gulf and
Atlantic oceans; rain clouds plus high heat equals
thunderstorms and lightning! |
| As Ben Franklin first proved in 1760 with just a kite,
string, and a key: lightning is electricity.
There are three basic kinds of lightning: 1)
cloud-to-cloud; 2) cloud-to-ground; and 3)
intra-cloud. Charged particles gather in the lower
part of the clouds and are attracted to charged particles
on the ground. If the earth's particles are positively
charged and the cloud's are negative, the static electricity
causes a spark to jump from the cloud to the ground.
If the opposite occurs, a positive spark spikes up to meet
the negative cloud (usually seen at the front edge of
the storm). Either way, when these sparks collide, a
sort of short circuit occurs and causes the bright flash we
know as lightning. In the latter
example, the strike is three times hotter and many times
starts a fire. Lightning travels at the speed of
light (186,000 miles per second). This quick blast
of energy only lasts just a few millionths of a second, up
to 100 million volts, and reaches a peak temperature of
60,000 degrees Fahrenheit. As a result, the air around it is
super-heated and causes shock waves that crash together
producing loud booms we know as thunder. Thunder
travels at the speed of sound (1,090 feet per second)
Therefore, it takes about five seconds to travel a mile.
A single bolt of lightning can discharge about 100 million
bolts of electricity and can travel as far a 10 miles from a
cloud. |
| "Divide by 5" rule: You can determine the
distance between yourself and a thunderstorm by counting the
time, in seconds, between the lightning flash and the
thunder, and dividing by 5; i.e., if thunder is heard 10
seconds after the flash, the storm is about two miles away.
Play it safe...if you can hear thunder, generally, you are
within striking range? |
| When viewed from a safe distance, a thunderstorm is one of
nature's most awesome and beautiful displays. When you
get caught by surprise and are forced to watch it "close up
and personal," it can be a very frightening and even deadly
experience!
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In a study by the Lightning Protection Institute (LPI),
it shows that more lightning casualties occur at home.
Out of 1,000 incidents, most occurred (in descending order):
1. on the telephone
2. in the kitchen
3. doing laundry
4. watching television
5. at a door or open window |
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In another three-year study by LPI, damages to
unprotected houses were examined. Results showed the
following strike points, in descending order of frequency:
1. roof and projections
2. television antenna
3. overhead power line
4. adjacent tree |
The Lightning Protection Institute recommends the
following protection standards:
- Lightning rods - a maximum of 20 feet apart
on high points of the roof and projections
- Main conductors - of heavy copper or aluminum
cable, interconnecting rods and grounds
- Bonds to metal bodies - to prevent sideflash
- Lightning arresters - to protect wiring and
appliances from surges following powerlines
- Tree protection - for any tree taller than
the house and within 10 feet
- Grounds - a least two half-inch diameter
copper-clad rods sunk ten feet deep in clay soil and
special grounding in sand, gravel, or rocky soil
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Lightning is hard on trees. Thousands of trees are
struck by lightning each day. Trees are usually the
tallest objects in the landscape. Their deep roots make
them nature's natural lightning rods, able to easily pass
electric current from the air down into the ground.
Taller
trees are more likely to be hit, not only because of their
height but also because they are more likely to suffer root
or stem decay. As a result, the plant tissue is wetter
and makes a better conductor. Lightning is nature's
way of eliminating old, sick trees. Lightning damage
may be minor or severe. Often, damaged trees become
victims of further damage from insects, diseases, or wind. |
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Lightning is five times hotter than the sun's
surface.
Lightning hits each square mile in Central Florida
40 times a year.
There can be as many as 500 cloud-to-cloud strikes
within a 45-minute storm.
The average flash could light a 100-watt light bulb
for more than 3 months.
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Myth - Lightning never strikes in the same place
twice.
Fact - The Empire State Building is struck about 23
times in an average year.
Myth - In medieval times church bells were rung
during thunderstorms, because people thought the sound waves
from the bells would suppress the lightning.
Fact - This belief was discarded when one historian
noted that in a 33-year period, 386 church towers were
struck and 103 bellringers killed.
Myth - Lightning follows the most direct path to the
ground.
Fact - It has been known to travel through clear air
and strike 10 miles from the storm like a "bolt from the
blue!"
Myth - Rubber-soled shoes protect you from a
lightning shock.
Fact - It is unreasonable and suicidal to think that
something so powerful as lightning can be stopped by a
half-inch of rubber.
Myth - Rubber tires on a car protect you from the
strike.
Fact - Actually, it's not the tires. The metal
body conducts the current around you, to the ground,
providing windows are rolled up and you are not touching the
metal. Not the case if it's a convertible,
utility, or 4x4 vehicle with a fiberglass roof! |