Lightning comes in all shapes and forms, it is a highly complex series of events to which to the naked eye we only see an end result...


This page has been updated Feb 2011


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* Remember, Lightning is the number one killer of people in storms.  You can be struck anytime, anywhere many miles from the storm itself..  Don't take unnecessary risks just for a photo - stay in the car or seek shelter out of the storm.


 

LIGHTNING: 

What is lightning?  How does it form?  What types of lightning are there?

 


 

 Lightning is one of nature's wonders.  From the curious observer to the lightning physicist, this natural and spectacular phenomenon has always been a topic of conversation and photography.  Underneath this awesome light show belies a serious side, lightning is highly dangerous.  You'd be surprised just how easy it is to be struck, although your chances of ever being a target are about 1:400,000 but that does not mean everyone should take precautions with thunderstorms, better the Devil you know.

 

THE LIGHTNING PROCESS 

Lightning is an electrical breakdown of opposite charge within a thunderstorm cloud.  There are many processes that have to be met to initiate lightning but all thunderstorms will have some form of lightning in them, even unseen by the observer even though thunder may be heard.  The formation of lightning is extremely complex but for a basic overview this is how it is formed:  A thunderstorm has an updraft, whereby air is drawn into the storm to allow convection to rise higher and higher, it also has a downdraft, which is the precipitation or rain falling back to earth through the storm's core which we regularly see.

At the freezing level water droplets begin to freeze and become supercooled water droplets having a coating of ice around them, they're still light enough to be lifted within the updraft and continue up until they are too heavy to remain there and fall.   Everything we know carries a charge,  positive & negativeSupercooled rain drops, hail, dust, are no different and this is what is so unique.  These ice crystals, hail or raindrops carry this charge throughout the storm, on the lower portion of the droplet is positive charge and at the top is negative charge.  As these collide in the storm over millions and millions of times, the charge is highjacked or stolen from each droplet.  Positive charge because it is lighter is carried aloft to the top of the storm, and the negative charge being heavier is carried by other droplets toward the lower region of the storm.

This is know as charge separation.  The process of lightning.  Opposites attract, so with each negative charge there are positive charges searching for a connection and visa versa.  Once they meet the breakdown process begins and this is what you see in thunderstorms; the continuous flashing.  These are intracloud or IC discharges and it is this that creates lightning strikes that come to earth.

 

 

CLOUD TO GROUND LIGHTNING

 


 

 



 SEVERAL TYPES OF CG LIGHTNING

BOLTS FROM THE BLUE



 

 

HIGH SPEED VIDEO FOOTAGE HAS IN RECENT YEARS BEEN AN ASTOUNDING TOOL IN WATCHING HOW LIGHTNING IS CREATED AND HOW IT WORKS.  TOM WARNER FROM THE USA IS A WORLD AUTHORITY IN THIS FIELD AND I HIGHLY RECOMMEND YOU VIEWING HIS SITE.


 

  Credited to http://smh.com.au/ and shows what happens when lightning strikes 20 feet away.  Check the step leader in the trees!

 

Streamer lightning

 






Intracloud lightning




 

 

Transient Luminous Events

 

The rarest and astonishing lightning types.  extremely hard to see with the naked eye unless you have an image enhancer on the end of your lens or video camera.  You need to be in total darkness with a perfect view of a lightning active storm, if you see them or capture them on video contact your local weather service and send it to them with a report - they would be very interested in it as not much is known about them.

(GRAPHIC AND TEXT COURTESY OF NOAA)


Large thunderstorms are capable of producing other kinds of electrical phenomena called transient luminous events (TLE's). The most common TLE's include red sprites, blue jets, and elves.

Red Sprites can appear directly above an active thunderstorm as a large but weak flash. They usually happen at the same time as powerful positive CG lightning strokes. They can extend up to 60 miles from the cloud top. Sprites are mostly red and usually last no more than a few seconds, and their shapes are described as resembling jellyfish, carrots, or columns. Because sprites are not very bright, they can only be seen at night. They are rarely seen with the human eye, so they are most often imaged with highly sensitive cameras.

Blue jets emerge from the top of the thundercloud, but are not directly associated with cloud-to-ground lighting. They extend up in narrow cones fanning out and disappearing at heights of 25-35 miles. Blue jets last a fraction of a second and have been witnessed by pilots.

Elves are rapidly expanding disk-shaped regions of glowing that can be up to 300 miles across. They last less than a thousandth of a second, and occur above areas of active cloud to ground lightning. Scientists believe elves result when an energetic electromagnetic pulse extends up into the ionosphere. Elves were discovered in 1992 by a low-light video camera on the Space Shuttle.



 

LIGHTNING - HOW IT ALL WORKS: 


As a thunderstorm moves over the Earth's surface, an equal but opposite charge is induced in the Earth below, and the induced ground charge follows the movement of the cloud.

An initial bipolar discharge, or path of  ionized air, starts from a negatively charged mixed water and ice region in the storm. The discharge ionized channels are called leaders. The negative charged leaders, called a "stepped leader", proceed generally downward in a number of quick jumps, each up to 50 meters long. Along the way, the stepped leader may branch into a number of paths as it continues to descend. The progression of stepped leaders takes a comparatively long time (hundreds of milliseconds) to approach the ground.

This initial phase involves a relatively small current (tens or hundreds of amperes), and the leader is almost invisible compared to the subsequent lightning channel.When a stepped leader approaches the ground, the presence of opposite charges on the ground enhances the electric field. The electric field is highest on trees and tall buildings. If the electric field is strong enough, a conductive discharge (called a positive streamer) can develop from these points
.



 

(the Democratic Republic of Congo is the lightning capital of the world...)


 

This was first theorized by Heinz Kasemir. As the field increases, the positive streamer may evolve into a hotter, higher current leader which eventually connects to the descending stepped leader from the cloud. It is also possible for many streamers to develop from many different objects simultaneously, with only one connecting with the leader and forming the main discharge path. Photographs have been taken on which non-connected streamers are clearly visible. When the two leaders meet, the electric current greatly increases. The region of high current propagates back up the positive stepped leader into the cloud with a "return stroke" that is the most luminous part of the lightning discharge.

 


Aircraft struck by lightning


 

 
Aircraft initiating lightning courtesy of Zen Kawasaki
Department of Electrical Engineering
Faculty of Engineering, Osaka University
Yamada-Oaka 2-1, Suita, Osaka)  This video above shows both upward and downward leader development - so the aircraft did not get struck by lightning, it created it.


 

When the electric field becomes strong enough, an electrical discharge (the bolt of lightning) occurs within clouds or between clouds and the ground. During the strike, successive portions of air become a conductive discharge channel as the electrons and positive ions of air molecules are pulled away from each other and forced to flow in opposite directions.

The electrical discharge rapidly superheats the discharge channel, causing the air to expand rapidly and produce a shock wave heard as thunder. The rolling and gradually dissipating rumble of thunder is caused by the time delay of sound coming from different portions of a long stroke



(NOAA radar sequence of lightning over Colorado USA)

 

LIGHTNING TRACKER COUNT OVER A VERY ACTIVE DAY IN THE NORTHERN TERRITORY WHERE I LIVE, PARTICULARLY IN DARWIN.  THE ONLY PROBLEM WITH LIGHTNING DETECTION NETWORKS HERE IN AUSTRALIA.  THESE ARE USEFUL FOR DISTRIBUTION OF LIGHTNING, BUT TELL NOTHING OF THE POLARITY.  LIGHTNING TRACKERS DO GIVE SEPARATE INCIDENCES OF TYPES, POLARITY BUT DO NOT GIVE POLARITY WHERE THE MARKERS ARE SITUATED FOR EACH STRIKE.  IN OTHER WORDS, THE TRACKER COULD SHOW +CG,-CG +IC ETC, BUT DO NOT SHOW 'WHERE' THESE POLARITIES ARE IN THE STORM AREAS.OF INTEREST.

 


 

TO GIVE SOME COMPARISON TO LIGHTNING DETECTION SYSTEMS, THIS GRAPHIC BELOW (COURTESY TOM WARNER) HIGHLIGHTS THE AMOUNT OF NEGATIVE STRIKES OVER THE TOP END REGION FOR A FULL NIGHT IN JANUARY.  WHILST THERE WERE POSITIVE DISCHARGES ACCOUNTED FOR, THIS MAP REINFORCES DATA THAT SHOWS 90% OF LIGHTNING IS NEGATIVELY CHARGED.  WINTER STORMS SEEM TO EXHIBIT HIGHER RATES OF POSITIVE DISCHARGE, THIS MAY BE DUE TO AN ABUNDANCE OF WATER DROPLETS SATURATING THE STORM, BUT FURTHER RESEARCH NEEDS TO BE DONE IN THIS AREA.  TYPICALLY, TROPICAL THUNDERCLOUDS ARE BRIEF IN DURATION ELECTRIFICATION WISE, NO MORE THAN 30 MINUTES

 

Lightning stroke density 

YOU CAN COMPARE BOTH GRAPHICS.  ONE HIGHLIGHTS THE AMOUNT OF STRIKES BUT NOT THE POLARITY.  THE ABOVE GRAPHIC HIGHLIGHTS BOTH DISTRIBUTION AND POLARITY

LIGHTNING SAFETY SHOULD ALWAYS BE THE FOREMOST IN YOUR MIND WHEN OUT TAKING THUNDERSTORM PHOTOS.  IF YOU HEAR THUNDER THEN TAKE SOME KIND OF SHELTER.  INSIDE THE CAR, UNDER A COVERED AREA.  IF YOU ARE UNABLE TO THEN AT LEAST TRY NOT TO BE THE TALLEST OBJECT IN A FLAT REGION.  POSITIVE CHARGE ALWAYS COLLECTS AROUND THE TOPS OF OBJECTS, AND THIS IS WHERE UPWARD LEADERS PROPAGATE.  IF LIGHTNING DOES STRIKE CLOSE TO YOU AND YOU ARE UNABLE TO SEEK SHELTER, THEN SQUAT DOWN ON YOUR FEET INTO A BALL AND WAIT TILL THE DANGER PASSES...IN HINDSIGHT YOU SHOULD NOT BE LEFT ALONG IN AN OPEN AREA AND IF THERE ARE TREES AROUND YOU TRY AND STAY WITHIN A GROUP OF TREES OF THE SAME HEIGHT TO LESSON YOUR CHANCES OF BEING HIT.

NO PHOTO IS WORTH BEING STRUCK OVER, NO MATTER HOW BRAVE YOU THINK YOU ARE OR HOW GOOD THE SHOT.  THUNDERSTORM AND LIGHTNING PHOTOGRAPHY IS HIGHLY DANGEROUS. EVEN THE MOST EDUCATED IN LIGHTNING RESEARCH ABSOLUTELY DO NOT STAND OUTSIDE DURING A STORM.  SO TAKE THAT AS A HINT.  I CERTAINLY HAVE FOUND OUT THAT IT'S FAR BETTER TO STAY IN THE CAR, STICK YOUR CAMERA ON THE DASHBOARD OR LEAVE THE CAMERA ON THE TRIPOD OUTSIDE THE CAR...YOU CAN CHECK THE IMAGES LATER WHEN YOU GET HOME!