 Have
a seat away from
everyone else.
 Take
tornado quiz
 Explain what causes
lightning.


Science Learning Center
Homework Center
http://video.pbs.org/video/1615154986/
1. How do scientists get better information on
lightning strikes?
2. What do scientists believe triggers lightning
strikes?

◦
What evidence is there to support this theory?

What do scientists currently believe trigger
lightning strikes?


Know what conditions are needed to form a
thunderstorm, and lightning bolts.
Experiment with electricity.

Analysis due Friday


Lightning is most commonly developed within
a thunderstorm
Lightning has also been seen within volcanic
eruptions, heavy snowstorms, and in large
hurricanes.

A thunderstorm forms in air that has three
components
◦ Moisture
◦ Instability
◦ Something such as a cold front to cause the air to
rise

The rising motions within the storm can build
a cloud from 6 to 10 miles above sea level.



At this elevation temperatures are much colder;
so ice begins to form in the higher parts of the
cloud
As the falling ice and sleet collides with the rising
moist air, it picks up extra electrons from the ice
and sleet.
The ice and sleet then deposits these electrons at
the bottom of the thunderstorm cloud.

The separation of charge is crucial for
lightning to form.

The separated charges cause the bolts of
lightning we see.

The more charge that is separated the bigger
the strike.
What are the three main components
needed to form a thunderstorm?
1.
◦ Moisture
◦ Instability
◦ Something such as a cold front to cause the air to
rise
What causes the bolts of lightning we see?
2.
◦
The separated charges



What does separation of charge mean?
Atoms are normally neutral (meaning they
have no charge)
However you can remove electrons from
certain atoms and put them somewhere else.


Some atoms (typically metals) don’t care
about all of their electrons so they can be
removed or shared with another atom.
How can you remove extra electrons from an
atom?




Balloon Demo
Opposites Attract Demos
Likes Repel Demo
Sparks Demos


How is static electricity built up in a
thunderstorm cloud?
The falling ice collides with the moist rising
air to transfer electrons to the bottom of the
cloud. Thus leaving the top of the cloud with
a positive net charge.



Know the differences and similarities of CG, CC,
and IC lightning strikes.
Understand the frequency of lightning strikes
around the world.
Know what causes thunder and be able to
calculate your distance from a lightning strike
based on the time delay of thunder.


Lightning is approximately 50,000 degrees
Fahrenheit
The average lightning bolt is hundreds of
millions of volts and typically about 50,000
amps
There are three types of lightning
 Cloud to Ground – 10%
 Cloud to Cloud and Intra-Cloud – 90%

CC and IC lightning are far more common than
CG lightning, but CG lightning has a greater
effect on humans so more research has been
done on that.

As a thundercloud moves over the surface of
the Earth it induces a positive charge on the
surface.
What happens to
the taller objects?
Can you become
the tallest object
around?

These two oppositely charged objects create
a strong electric field.

An electric field stores energy that can be
released at a later time. Similar to a battery.

Once triggered this energy is released in the
form of a lightning bolt.



Normally air is an insulator and will not let
electrons flow through it.
When enough energy is applied, a path to
Earth becomes “ionized”.
This ionized path is light a highway for the
electrons to travel on.


Once the bottom of the cloud and the Earth’s
surface are neutral again, the ionized
highway closes down.
While that path of air is ionized, the air acts
as a conductor instead of an insulator.
What are the three types of lightning?
1.
Why does the Earth have a positive charge
when a thunderstorm cloud is above it?
2.
◦
The negative charge at the bottom of the cloud
induces a positive charge on the ground
(Opposites attract)


Lightning seems to happen is one bright bolt
but is that really what happens?
Let’s take a look:
◦ https://www.youtube.com/watch?v=JVXy-ZqqZ-g

Soccer: (1:35)
◦ https://www.youtube.com/watch?v=MNJRPOltifI


Why does the main lightning bolt seem to
pulse in slow motion?
It takes the electrons a few moves from cloud
to ground and back to cloud until they are
evenly distributed.


This is more common than CG lightning, but
it doesn’t cause nearly as much destruction
because it doesn’t hit anything or anyone.
It also won’t appear as bright or as loud
because it is buried in the cloud, and typically
further away than CG lightning.


CC lightning occurs between two separate
clouds.
The lightning process is the same as CG, but
it between a negative part of one cloud and a
positive part of a different cloud.

IC lightning is when a lightning bolt strikes
within one thunderstorm cloud.
◦ Lightning bolt between the positive top and
negative bottom of the thundercloud.

This is even more common than CC lightning
because the particles in the thundercloud
make it easier to conduct electricity.
1.
Does lightning ever strike the same
spot twice?
2.
Explain the differences between CG,
CC, and IC lightning strikes.
3.
How are CG, CC, and IC lightning
strikes similar?

What is the purpose of a lightning rod?
◦ https://www.youtube.com/watch?v=zhu5pIrPw7U

Lightning Rod Demo

Why doesn’t lightning strike when the
lightning rod is attached?


The lightning rod allows a positive charge to
continuously flow into the clouds so there
isn’t a huge build up of charge.
Without the build up of charge lightning will
not strike!

On Earth, the frequency of lightning is
approximately 40 to 50 times a second!
◦ That’s nearly 1.4 billion flashes per year!


At any given moment, nearly 1,800
thunderstorms are in progress over the
surface of Earth.
Lightning strikes everywhere on Earth, but is
more common on land over the tropics (70%)

Florida sees more lightning than any other
area in the USA
◦ Lightning Alley is from Tampa to Orlando
◦ As many as 50 strikes per square mile a year

The Empire State Building is struck on
average 23 times each year
◦ Was once struck 8 times in 24 minutes


On average the US has 100,000
thunderstorms each year.
That’s about 274 thunderstorms every day!

This website tracks every lightning strike in
America…
◦ http://www.weather.com/maps/activity/golf/usligh
tningstrikes_large.html

http://www.eldoradocountyweather.com/ligh
tning/swn-lightning.html
1.
2.
Which state has the most lightning strikes
per year?
How many lightning strikes happen per
second across the world?


Thunder is the sound caused by lightning
It is so loud because it is a sonic boom.
◦ Meaning that it has so much energy that is causes
the air particles to move faster than the speed of
sound

Thunder IS NOT the collision of clouds.
There must be lightning for there to be
thunder.


The distance of the lightning can be
calculated by the listener based on the time
interval from when the lightning is seen to
when the sound is heard.
The lightning is approximately one mile away
for every 5 seconds between sound and flash.

How far away is the lightning bolt if you see
the flash and the 15 seconds later you hear
the thunder?
1 𝑀𝑖𝑙𝑒
𝑥

=
5 𝑆𝑒𝑐𝑜𝑛𝑑𝑠
15 𝑆𝑒𝑐𝑜𝑛𝑑𝑠
15 𝑆𝑒𝑐𝑜𝑛𝑑𝑠 1 𝑀𝑖𝑙𝑒

=𝑥
5 𝑆𝑒𝑐𝑜𝑛𝑑𝑠

3 𝑀𝑖𝑙𝑒𝑠 = 𝑥
𝑵𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝑺𝒆𝒄𝒐𝒏𝒅𝒔
= 𝑯𝒐𝒘 𝒇𝒂𝒓 𝒂𝒘𝒂𝒚 𝒊𝒕 𝒊𝒔
𝟓
1.
2.
What causes thunder?
If you see a lightning flash and then
hear thunder 10 seconds later, how
far away was the lightning?





Heavy rains which can cause flash flooding
Strong winds
Hail
Lightning
Tornadoes



Lightning is a major threat during a
thunderstorm.
The power of lightning’s electrical charge and
intense heat can split trees, ignite fires, and
cause electrical failures.
In the US between 75 and 100 Americans are
hit and killed each year by lightning.




Approximately 10,000 forest fires are started
each year by lightning.
More deaths from lightning occur on the East
Coast.
More forest fires are started in the West.
Winds exceeding 100 mph are responsible for
most thunderstorm damage.

Most lightning fatalities occur as a result of
near hits not direct hits.
◦ Direct hit – enormous quantities of energy pass
through the body very quickly. Resulting in internal
burns and organ damage, explosions of flesh and
bone, and damaged nervous system.

Indirect hit – Ground charges race through
the ground and towards the lightning bolt.
It is easier for them to travel through your
legs than the ground because your legs are
more conductive than the ground.


Large hail results in nearly $1 billion in
damage to property and crops.
Approximately $100 million in annual losses
result from forest and building fires caused
by lightning.

The rising motions within the storm can build
a cloud from ___ to ____ miles above sea
level.


Understand the purpose and function of a
lightning rod.
Know the proper safety procedures for a
thunderstorm.

Missing work

Thunder and Lightning Quiz this Friday

https://www.youtube.com/watch?v=eNxDgd
3D_bU
1.
2.
No place outside is safe during a
thunderstorm!
Use the 30-30 rule!
◦ If the time between lightning and thunder is 30
seconds or less, go to a safer place.
◦ If the lightning can’t be seen, just hearing thunder
means you should go to a safer location.
◦ Wait at least 30 minutes after hearing the last
thunder before leaving the safer location.
3.
4.
The best safest location from lightning is a
typical house.
You can be injured inside a house. Stay
away from corded telephones, plumbing,
and anything electrical that is plugged into
the wall. Don’t watch lightning through a
window or open doorway.
The top activities for lightning casualties in
the US are:
5.
◦
◦
◦
◦
◦
◦
◦
Open fields and elevated places
Under trees (or other tall isolated objects)
Water related activities
Golfing
Open Vehicles (farm, construction, etc)
Telephone
Radio and radio equipment
6.
7.
8.
9.
Outdoor sports have the fastest rising
lightning causality rate.
Open picnic pavilions and rain shelters offer
absolutely no protection from lightning
When outside, appoint someone to be the
lightning monitor.
Lightning First-Aid: Call 911, CPR


Why don’t lightning rod get struck by
lightning?
What is the safest place during a lightning
strike?

You will have a short quiz on lightning Friday

Study your notes!