What is a thunderstorm? A storm resulting from strong rising air currents accompanied by rain, thunder, and lightning The typical thunderstorm is 15 miles in diameter and last an average of 30 minutes. Nearly 1,800 thunderstorms are occurring at any moment around the world. That’s 16 million a year!

What does a thunderstorm need? –Moisture –Unstable air – usually warm air that can rise rapidly –Lift – fronts, breezes, or mountains that help lift air

Formation – Stage 1 Developing Stage, also called Cumulus Stage cumulus cloud pushed upward by a rising column of air called an updraft cumulus cloud continues to grow into a towering cloud little to no rain during this stage but occasional lightning lasts about 10 minutes Developing stage seen here

East Brunswick thunderstorms forming on June 2, 2013 by Grace Ding

Formation – Stage 2 Mature Stage –The updraft continues to feed the storm, but precipitation begins to fall out of the storm, creating a downdraft (a column of air pushing downward). –The mature stage is the most likely time for hail, heavy rain, frequent lightning, strong winds, and tornadoes. The storm sometimes appears black.

Formation – Stage 3 Dissipating Stage –Downdraft begins to overcome the updraft. Rainfall decreases in intensity, but lightning remains a danger. WatchKnowLearn - Free Educational Videos for K-12 Students WatchKnowLearn - Free Educational Videos for K-12 Students

Question… What are the 3 main ingredients for thunderstorm development? A. Moisture, cold air, and lift B. Moisture, warm air, and lift C. Dry air, warm air, and lift D. Dry air, cold air and lift

Question… What are the 3 main ingredients for thunderstorm development? A. Moisture, cold air, and lift B. Moisture, warm air, and lift C. Dry air, warm air, and lift D. Dry air, warm air and lift Observe an animation of a thunderstorm.

Frequency of thunderstorms

Types of thunderstorms There are 3 types of thunderstorms –Single-cell –Multi-cell –Super-cell

Super-cell Thunderstorms highly organized storm with severe updraftshighly organized storm with severe updrafts winds can reach mph different from other storms due to presence of rotating updrafts that produce giant hail, strong downbursts (80 mph or more), straight line winds, and tornadoesdifferent from other storms due to presence of rotating updrafts that produce giant hail, strong downbursts (80 mph or more), straight line winds, and tornadoes

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Dangers of Thunderstorms Thunderstorms can cause damage by: Flash floods Lightning Strong winds Hail Tornados (only from a super-cell)

Fun Fact One thunderstorm has 275 million gallons of water in it. That amount of water goes over the Niagara Falls every 6 minutes!

Flash Floods a rapid rise of water along a stream or low- lying urban area occur within 6 hours of a significant rain event usually caused by intense storms that produce heavy rainfall in a short time very strong - can roll boulders, uproot trees, scour out new channels, and destroy buildings and bridges

Oregon, November 2007

On April 15, 2007, between 5 and 10 inches of rain fell in NJ

Rain Gauging Station on the Hackensack River

Hackensack River flooding in Rivervale, NJ. This photo was taken BEFORE the river reached its peak!

Elm Street, Hackensack, New Jersey

Route 18 at Commercial Boulevard in New Brunswick

Easton Avenue, Somerset

Raritan River near the Rutgers football stadium

Rutgers Crew boat house along route 18

Route 18

Piscataway – note the hot tub floating down the street!

What is lightning? a gigantic electrostatic discharge between the cloud and the ground, between clouds, or within a cloud the same kind of electricity that can shock you when you touch a doorknob (static electricity) results from buildup and discharge of electrical energy between positively and negatively charged areas.

Lightning strikes somewhere on Earth 100 times every second! Each year lightning strikes the USA 20 million times!

Most cloud to ground lightning – central Florida Almost no lightning – Pacific Northwest

How Does Lightning Work? 1. Wind creates friction in an ice cloud that creates “static electricity.” The bottom of a cloud becomes negatively charged. Since opposites attract, positive charges collect on the ground and other surfaces under the cloud.

How Does Lightning Work? 2. A stepped leader —a negative electrical charge made of zig- zagging segments, or steps—comes partway down from the cloud. The steps are invisible. Each step is about 150 feet long.

How Does Lightning Work? 3. When the stepped leader gets within 150 feet of a positive charge, a streamer (a surge of positive electricity) rises to meet it. The leader and the streamer make a channel.

How Does Lightning Work? 4. An electrical current from an object on the ground surges upward through the channel. It touches off a bright display called a return stroke.

In this 5 minute time exposure photo, lightning strikes Tucson, AZ. Each flash contains 1 billion volts of electricity, enough to light a 100 watt bulb for 3 months.

Lightning happens in ½ a second flash superheats the air to 50,000 ºF, –5 times hotter than the sun! causes a shock wave that results in thunder –Thunder - the booming sound produced by rapidly expanding and vibrating air along the path of the lightning.

Ball lightning occurs after a ground flash. The ball is usually red, orange, or yellow, and can be as small as a grapefruit or as big as a pumpkin. The ball hovers or darts briefly, fizzles out and ends with a loud BANG!

Cloud lightning never strikes Earth.

Spider lightning flashes crawl across the sky for up to 90 miles.

Benjamin Franklin In 1752 the famous scientist and statesman conducted an experiment that proved that lightning is electricity. He invented lightning rods to protect buildings from being struck and catching fire. Prior to his invention, because the church tower was usually the highest structure, it was the building most often hit by lightning. The buildings burned. Parishioners were told NOT to go to the church to seek shelter during a storm. Lightning starts many fires in the western US and Alaska.

An early form of lightning protector shows how the electricity is sent to the ground where it dissipates.

More modern lightning rods use guide wires to send the electrical charge safely into the ground. Parents “ground” their children. Get it?

Lightning Safety FUN FACT The Empire State Building in New York City is struck on average more than 100 times per year. The building is actually designed to simulate a giant lightning rod in order to help protect the other buildings in the surrounding area.

Where and when are you most likely to be struck? Florida has twice as many lightning casualties as any other state. Most lightning casualties occur between noon and 4 p.m. Sunday has 24% more deaths than other days, followed by Wednesday. Lightning reports peak in July.

Men are struck 4 times more often than women. Men represent 84% of deaths and 82% of injuries. Victims suffer from paralysis, memory loss, burns, loss of sight or hearing, and other neurological problems. Only percent of lightning victims are struck dead. Doctors do not know how to treat victims who survive. The pathology of lightning, or keraunopathy, is known only to a few specialists. Many victims were walking in an open field or swimming before. Others were holding metal objects such as golf clubs, fishing rods, hay forks, or umbrellas.

What are your chances? In your lifetime, your odds of being struck by lightning are 1 in 10,000. Your chance of being killed by lightning in any particular year is 1 in 775,000. In NJ, the average annual number of lightning deaths is 2. The leading cause of lightning death in the home is talking on a corded telephone.

Where is the storm? Sound travels more slowly than light, so we see the lightning before we hear the thunder. Count the seconds between a flash of lightning and the next clap of thunder. Divide by 5 to determine the distance to the lightning in miles. By the time you hear thunder, you are already within striking distance!

How far away is it? You see lightning and begin counting. You count to 10. How far away is the storm? –10 divided by 5 –equals 2 miles

Thunder Lightning emits a broadband pulse of radio waves that our ears cannot detect. Picked up by specialized equipment, lightning sounds like bacon frying or the crackling of a campfire. Scientists call the sounds tweeks, whistlers and sferics. Sometimes lightning bolts escape the ionosphere and travel along Earth’s magnetic field!

If you can hear thunder you are already in danger of being struck by lightning. When thunder roars, go indoors!

Fulgurite Sometimes when lightning strikes sand, the sand is superheated. It melts and then fuses together to form a fulgurite. These take the form of tubes, sometimes more than half inch in diameter, that look like lightning bolts. Rock Fulgurites are formed when lightning strikes the surface of a rock, melting and fusing the rock. The melting point of Si0 2 is 2950 o F.

Fulgurite

True Lightning Stories The Empire State Building and the Sears Tower are struck thousands of times each year! A watermelon on a kitchen table in Arkansas blew up during a thunderstorm in A clap of thunder caused it to vibrate so fast that it exploded! A field of potatoes was struck by lightning. The potatoes were cooked by the strike. After being dug up, they were eaten like baked potatoes!

Lightning Joke Teacher: Why is it said that lightning never strikes the same place twice? Student: Because after it’s struck once, the same place isn’t there anymore!