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Meteorology - PowerPoint Presentation

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Meteorology - PPT Presentation

Unit 5 Lightning History Lightning as a safety threat receives less attention than hurricanes tornadoes and flash floods Usually kills only one person at a time Lightning has historically been the leading cause of weather related death ID: 585191

charged lightning cloud flash lightning charged flash cloud particles energy ground injuries thunder strike death side lighting discharge light

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Slide1

Meteorology

Unit 5 - LightningSlide2

History

Lightning as a safety threat receives less attention than hurricanes, tornadoes, and flash floods.

Usually kills only one person at a time

Lightning has historically been the leading cause of weather related death

In

recent years, flash flooding has caused more fatalitiesSlide3

What is lightning?

Lightning - Energy

in the form of discharged

heat and light Slide4

How does lightning form?Slide5

Hang on… it gets complicatedSlide6

Lightning Formation

Storms

are

positively charged on the top of the cloud and negatively charged on the bottom

The ground is usually negatively charged but reverses polarity when a storm passes

over, becoming positive

Within a cloud, water and ice particles are constantly moving past

each other

due to the convective currents

The particles become charged (think like static electricity and a balloon)

More convection = more electrical potential

If there enough turbulence in the cloud, the charged particles begin to separate

Charged particles seek their opposites in order to neutralizeSlide7

Leaders & Streamers

Streamers

of

negatively charged

particles come down from the cloud and attract

leaders

of

positively charged

particles from the

surface

When the pathway between the

streamers

and leaders is complete, a spark is formed, and energy is discharged as heat and lightSlide8

Lightning Types

C

loud-to-ground lightning – the charged pathway reaches from the cloud to the ground

In-cloud lightning - The

charged particles may find each other and discharge energy within the cloud. Slide9

Lightning Facts

A flash of lighting can produce 1 billion volts of energy or up to 200,000 amps.

Flashes can be 3 miles long, but only 1-3 cm wide

A single flash of lightning unleashes as much energy as blowing up a ton of dynamite

A strike is made up of between three and twelve individual lightning “strokes” each lasting only a few thousandths of a second

One

storm

in the Midwest produced over 15,000 lightning strikes to ground in a 6 hour periodSlide10

St. Elmo’s fire

St. Elmo’s fire – A gap in electrical discharge. Can be seen as blue light sometimes preceding a lightning strikeSlide11

What is thunder?Slide12

Thunder

Thunder is the sound produced by lightning’s discharge of energy

Lightning travels around 300 million m/s and sound travels at 300 m/s

The difference creates a shockwave, which is the sound we hear as thunder

To determine the distance you are from the storm, count the seconds between the lightning flash and thunder and divide by 5. This is the approximate distance in miles from you to the lightningSlide13

What happens when lightning strikes?

Lightning

can cause structural damage, structural fires, and forest fires

Lightning

kills and injures in two ways:

Direct strike

Side flashSlide14

Death and Injury

Lighting deaths average around 40 per year in the USA

Lighting causes 2.5 times more injuries per year than deaths

Men are injured significantly more often than womenSlide15
Slide16

Injuries - ExitSlide17

Injuries – Lichtenberg FiguresSlide18

Lightning InjuriesSlide19

Side Flash

Side Flash- lightning striking near a person

Can cause injury, blindness, deafness, or death

Depends on many factors

Distance to the ground strike point

Soil conductivity (wet soil conducts better than dry soil)

Strength of electric current

Most common outdoors but can happen indoors through phones, electrical appliances, and water pipes connected to sinks, showers, and bathsSlide20

Side FlashSlide21

Death and Injury

The most common deaths and injuries due to lightning occur

Near or in water

Near or under a tree

Near a vehicle, home, or building

On a golf course, ball field, or in other open areas.Slide22

What do I do??Slide23

Safety

Pay more attention to lightning than to rain

Plan ahead

DON’T BE THE HIGHEST OBJECT

Don’t be near or connected to anything taller than its surroundings, like trees or buildings

Go into a building or vehicle with a solid

metal roof.

Do

not

contact any metal.Slide24
Slide25

Worst Case Scenario

Lightning may be about to strike if:

Your hair is standing on end

Your skin begins to tingle

You hear clicking sounds

You see St. Elmo’s Fire

No longer recommended –

Crouch

on the balls of your

feet

to minimize your surface

area in contact with the groundSlide26

Worst Case Scenario

Now recommended – RUN.Slide27

Worst Case Scenario

RUN

Keeps you moving towards a safe place

Only one foot touching

the ground at a time

Distance from others