Lightning

Background facts about lightning Hot enough to melt sand! Travels at 140,000mph Is found on Jupiter, Saturn, Venus, Uranus Not created the same as on earth, but similar Jupiter Saturn

Background facts about lightning Average length: 5 Miles long Record Length over Dallas, TX: 118 Miles long Unfortunate record Roy Sullivan Between 1942 and 1977, struck 7 times and survived them all

Lightning can be a variety of colors (blue, green, red) Caused by what is in the air that the lightning is traveling through Air makeup also affects the path the lightning will take, and how strong the bolt can be

How is lightning created? Charging by Friction Ice falling (-) Water rising (+) Cloud becomes polarized (top +, bottom -) Charging by Friction Water Rises Ice Falls

Induced charge in ground Negative charges pushed away, leaving positively charged objects on the ground

Enough charge is built up and charges flow (lightning bolt) Dielectric breakdown of air (failure of an insulator) in this case, air (3,000,000 V/m)

Leaders and Streamers Step Leaders Streamers Come down from cloud Come up from Earth Streamer Step leader http://www.youtube.com/watch?v=RDDfkKEa2ls&feature=related Streamers http://www.youtube.com/watch?feature=fvwp&v=6MUYsIjTKvk&NR=1 Leaders

Leader (from cloud)

Streamer (from ground)

Fulgurite Lightning melts the sand Forms hollow tubes $1 -> $2.5 per gram

Lightning Safety http://www.youtube.com/watch?v=KVzpV3V_V3U&feature=related Plane refueling

People can survive because How you can get struck Direct strike Lighting strikes you directly Splash Injury lightning jumps from an object and strikes you Contact you are in contact with an object that is struck by lightning Ground Lightning can travel through the ground and go up one leg and down the other People can survive because Lightning usually doesn’t pass through the heart Cardiac arrest most common cause of death Very hot, but passes through your body for only split second

Safety Places to avoid Where should you go? Tall objects, metal objects, wide open areas, water Don’t use a landline phone Where should you go? Inside a building, or in a car (as long as it’s not a convertible) Not because of the rubber tires!

Lightning Safety Faraday Cages http://www.youtube.com/watch?v=5IRfbC0RHsY Plane struck by lightning Start at 0:35 http://www.youtube.com/watch?v=nQgO18qk1_k&feature=related Tesla Coil / Faraday Cage

How does a Faraday Cage work? Faraday cage has to be grounded Lightning will take the easiest path to ground, through the Faraday Cage

Lightning Safety Lightning Rods Doesn’t always prevent lightning strikes Gives lightning a path around your house Positives attracted to the top of the rod, negatives repelled out of the rod

Grounding an Object Need to bury a grounding rod at least 8ft into the ground Otherwise, the lightning will spread across the surface of the earth and a person standing near could get shocked

What about the Fish??? Lighting rarely kills fish because when it strikes water it spreads across the surface, not down into the water But if a fish is near the surface, it will get fried

Lightning Safety Franklin Bells Invented by Ben Franklin Early warning device to detect lightning storms One bell hooked up to lightning rod One bell hooked up to ground Metal ball in between the bells To Lightning Rod To Ground

Can lightning be used as an alternative Energy Source? It can, but it’s not practical Average bolt won’t even produce enough electricity to power an average house for half a month Not consistent Too much current >100,000amps Average product needs 10-30amps