Lightning is an atmospheric discharge of electricity accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms. In the atmospheric electrical discharge, a leader of a bolt of lightning can travel at speeds of 60,000 m/s (130,000 mph), and can reach temperatures approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into glass channels known asfulgurites which are normally hollow and can extend some distance into the ground.There are some 16 million lightning storms in the world every year.
How lightning initially forms is still a matter of debate: Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, friction, and atmospheric pressure) to the impact of solar wind and accumulation of charged solar particles. Iceinside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud, thus assisting in the formation of lightning.
The irrational fear of lightning (and thunder) is astraphobia. The study or science of lightning is called fulminology, and someone who studies lightning is referred to as a fulminologist.
Historical Scientific research : Benjamin Franklin (1706–1790) endeavored to test the theory that sparks shared some similarity with lightning by using a spire which was being erected in Philadelphia. While waiting for completion of the spire, he got the idea to use a flying object such as a kite. During the nextthunderstorm, which was in June 1752, it was reported that he raised a kite, accompanied by his son as an assistant. On his end of the string he attached a key, and he tied it to a post with a silkthread. As time passed, Franklin noticed the loose fibers on the string stretching out; he then brought his hand close to the key and a spark jumped the gap. The rain which had fallen during the storm had soaked the line and made it conductive
Franklin was not the first to perform the kite experiment. Thomas-François Dalibard and De Lors conducted it at Marly-la-Ville in France, a few weeks before Franklin's experiment. In his autobiography (written 1771–1788, first published 1790), Franklin clearly states that he performed this experiment after those in France, which occurred weeks before his own experiment, without his prior knowledge as of 1752.
PROPERTIES : An average bolt of negativelightning carries an electric current of 30,000 amperes("amps") — 30 "kiloamps" (kA), and transfers five coulombs ofelectric charge and 500 millionjoules — 500 "megajoules" (MJ) of energy. Large bolts of lightning can carry up to 120 kA and 350 coulombs. The voltage is proportional to the length of the bolt.
An average bolt of positive lightning carries an electric current of about 300 kA — about 10 times that of negative lightning
Polarization mechanism hypothesis
The mechanism by which charge separation happens is still the subject of research. Another hypothesis is the polarization mechanism, which has two components
1.Falling droplets of ice and rain become electrically polarized as they fall through the Earth's natural electric field;
2.Colliding ice particles become charged by electrostatic induction.
As a thundercloud moves over the surface of the Earth, an electric charge equal to but opposite the charge of the base of the thundercloud is induced in the Earth below the cloud. The induced ground charge follows the movement of the cloud, remaining underneath it.
An initial bipolar discharge, or path of ionized air, starts from a negatively charged mixed water and ice region in the thundercloud. Discharge ionized channels are known as leaders. The negatively charged leaders, generally a "stepped leader", proceed downward in a number of quick jumps (steps). 90 percent of the leaders exceed 45 m (148 ft) in length, with most in the order of 50 to 100 m (164 to 492 feet)
DISCHARGE : 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
It has been discovered in the past 15 years that among the processes of lightning is some mechanism capable of generating gamma rays, which escape the atmosphere and are observed by orbiting spacecraft. Brought to light by NASA's Gerald Fishman in 1994 in an article in Science, these so-called terrestrial gamma-ray flashes (TGFs) were observed by accident, while he was documenting instances of extraterrestrial gamma ray bursts observed by the Compton Gamma Ray Observatory (CGRO). TGFs are much shorter in duration, however, lasting only about 1 ms.
RE STRIKE : High speed videos (examined frame-by frame) show that most lightning strikes are made up of multiple individual strokes. A typical strike is made of 3 to 4 strokes. There may be more.
Each re-strike is separated by a relatively large amount of time, typically 40 to 50 milliseconds. Re-strikes can cause a noticeable "strobe light" effect.
Each successive stroke is preceded by intermediate dart leader strokes akin to, but weaker than, the initial stepped leader. The stroke usually re-uses the discharge channel taken by the previous stroke.
The variations in successive discharges are the result of smaller regions of charge within the cloud being depleted by successive strokes
Because the electrostatic discharge of terrestrial lightning superheats the air to plasma temperatures along the length of the discharge channel in a short duration, kinetic theory dictates gaseous molecules undergo a rapid increase in pressure and thus expand outward from the lightning creating a shock wave audible as thunder
Since the sound waves propagate not from a single point source but along the length of the lightning's path, the sound origin's varying distances from the observer can generate a rolling or rumbling effect. Perception of the sonic characteristics are further complicated by factors such as the irregular and possibly branching geometry of the lightning channel, by acoustic echoing from terrain, and by the typically multiple-stroke characteristic of the lightning strike.
1. Cloud-to-ground lightning
This is the best known and second most common type of lightning. Of all the different types of lightning, it poses the greatest threat to life and property since it strikes the ground. Cloud-to-ground lightning is a lightning discharge between acumulonimbus cloud and the ground. It is initiated by a leader stroke moving down from the cloud.
Bead lightning is a type of cloud-to-ground lightning which appears to break up into a string of short, bright sections, which last longer than the usual discharge channel. It is relatively rare. Several theories have been proposed to explain it; one is that the observer sees portions of the lightning channel end on, and that these portions appear especially bright. Another is that, in bead lightning, the width of the lightning channel varies; as the lightning channel cools and fades, the wider sections cool more slowly and remain visible longer, appearing as a string of beads
Ribbon lightning occurs in thunderstorms with high cross winds and multiple return strokes. The wind will blow each successive return stroke slightly to one side of the previous return stroke, causing a ribbon effect.
Staccato lightning is a cloud to ground lightning strike which is a short-duration stroke that appears as a single very bright flash and often has considerable branching
Forked lightning is a name, not in formal usage, for cloud-to-ground lightning that exhibits branching of its path.
Ground-to-cloud lightning is a lightning discharge between the ground and a cumulonimbus cloud initiated by an upward-moving leader stroke. It is much rarer than cloud-to-ground lightning. This type of lightning forms when negatively charged ions called the stepped leader rises up from the ground and meets the positively charged ions in a cumulonimbus cloud. Then the strike goes back to the ground as the return stroke
Sheet lightning is an informally applied name to cloud-to-cloud lightning that exhibits a diffuse brightening of the surface of a cloud caused by the actual discharge path being hidden.
It is a form of cloud discharge, generally horizontal and at cloud base, with a luminous channel appearing to advance through the air with visually resolvable speed, often intermittently
UPPER ATMOSPHERIC LIGHTNING
Reports by scientists of strange lightning phenomena about storms date back to at least 1886. However, it is only in recent years that fuller investigations have been made. This has sometimes been called megalightning
Sprites are large-scale electrical discharges that occur high above athunderstorm cloud, or cumulonimbus, giving rise to a quite varied range of visual shapes. They are triggered by the discharges of positive lightning between the thundercloud and the ground
Blue jets differ from sprites in that they project from the top of the cumulonimbus above a thunderstorm, typically in a narrow cone, to the lowest levels of the ionosphere 25 miles (40 km) to 50 miles (80 km) above the earth.They are also brighter than sprites and, as implied by their name, are blue in colour. They were first recorded on October 21, 1989, on a video taken from the space shuttle as it passed over Australia, and subsequently extensively documented in 1994 during aircraft research flights by the University of Alaska.
Elves often appear as dim, flattened, expanding glows around 250 miles (402 km) in diameter that last for, typically, just one millisecond. They occur in the ionosphere 60 miles (97 km) above the ground over thunderstorms. Their colour was a puzzle for some time, but is now believed to be a red hue. Elves were first recorded on another shuttle mission, this time recorded off French Guiana on October 7, 1990
CLOUD TO CLOUD LIGHTNING
Lightning discharges may occur between areas of cloud without contacting the ground. When it occurs between two separate clouds it is known as inter-cloud lightningand when it occurs between areas of differing electric potential within a single cloud, it is known as intra-cloud lightning. Intra-cloud lightning is the most frequently occurring type
Over the centuries, lightning in cultures was viewed as part of a deity or a deity in of itself. One of the most classic portrayals of this is of theGreek God Zeus. An ancient story is when Zeus was at war against Cronus and the Titans, he released his brothers, Hades and Poseidon, along with the Cyclopes. In turn, the Cyclopes gave Zeus the Thunderbolt as a weapon, which was near the beginning of Zeus himself. The thunderbolt became a popular symbol of Zeus and continues to be today.
The Aztecs also portrayed Lightning as a supernatural power of a god, The Aztec had a god named Tlaloc. In mythology, the god was the bringer not only of beneficial rain but of storms, killer lightning bolts, flood, and disease.
In Slavic mythology the highest god of the pantheon is Perun, the god of thunder and lightning. Perkūnas was the common Baltic god of thunder, one of the most important deities in the Baltic pantheon. In both Lithuanian and Latvian mythology, he is documented as the god of thunder, rain, mountains, oak trees and the sky.
In the Jewish religion, a blessing "...He who does acts of creation" is to be recited, upon sighting lightning. The Talmud refers to the Hebrew word for the sky, ("Shamaim") - as built from fire and water ("Esh Umaim"), since the sky is the source of the inexplicable mixture of "fire" and water that come together, during rainstorms. This is mentioned in various prayers and discussed in writings of Kabbalah.
In Islam, God has said in the Quran, "Have you not seen how God makes the clouds move gently, then joins them together, then makes them into a stack, and then you see the rain come out of it.... (Quran, 24:43)" The preceding verse, after mentioning clouds and rain, speaks about hail and lightning, "....And He sends down hail from mountains (clouds) in the sky, and He strikes with it whomever He wills, and turns it from whomever He wills. The vivid flash of its lightning nearly blinds the sight.
Sometimes, while watching the sky during rains, one might just watch, a FLASH . It would just lighten the area. It doesn't have any foramations.
While photographing , one must follow these points (According to my knowledge and elders' experience)
1. Tripod is a must , or else pictures will be "out of focus".
2. Should make use of umbrella, as it might rain when you shoot.
3. Camera Settings :
i. Use f/5.6 to f/8 aperture, with iso 200.
ii. As far as possible use wide angle lenses. I have used Nikon 18-105mm lens. But usually compose the picture within 18mm-28mm.
iii. It is better if pictures are shot from a taller place. It may be hillocks or tall buildings. This is because, you will have a good view of the horizon , and also you can include the other parts of the city.
iv. keep the camera in "manual"
mode and make use of manual focussing.
iii. Keep the shutter speed in "Bulb" mode.
iv. Anticipate with the conditions.
v. Never keep checking your pictures in the LCD monitor. You can see them later. This is because, when you are viewing your pictures , there is a chance of striking of lightning. This may result in a loss of a good picture.