why do lightning reach the earth surface if it is but a spark caused by positive and negative collusions.?
138725
You're right--lightning is just a spark. BUT it's a spark caused by massive voltage. Voltage can be defined as a difference in electrical potential between two points, with one point having a high negative electrical charge, the other a high positive electrical charge. This difference in electrical potential can become enormous when a thunderstorm gets going full force.\n\nRain and/or hail in the storm clouds are violently rubbed together by high-velocity winds, thus building up a net negative electrical charge (abundance of electrons). On the ground below the clouds no such action takes place, thus the ground has a net positive electrical charge (deficiency of electrons).\n\nEven though air is a very good insulator, the difference in electrical potential (voltage) between the storm clouds and ground can quickly reach as high as 500,000 volts, more than enough to produce a lightning "spark."
665153
The exact reason is not proven, but suspected that it is because precipitation falls to the ground carrying electrons, and the lightning occurs when the difference in charges between the clouds and the ground even out, and the electrons jump back to the clouds.  That is why lightning is said to go from ground to the clouds.
42099
lightning occurs when warm air hits cooler air causing friction.  lightning during a snow storm is rare because warm air is harder to come by, however it happens occaissonally when a cold front follows a period of unseasonably warm weather.
207734
no, its a myth.  lightning is attracted to tall objects and metal objects (like lightning rods) so these get hit more often.
224271
Hello,\nLightening is caused due to the build up of electrons in the upper layers of the clouds during a storm. These electrons are attracted towards the positive potential of the earth, but the air gives a stiff resistance and does not allow the electricity to pass through. But when a huge potential has been accumulated, the electricity forces its way through the air molecules. This causes a lot of friction and hence releases heat energy. A tremendous amount of heat energy. This causes the air molecules to vibrate and this produces the cracking sound known as thunder. Thunder rattles the windows if it is loud enough. Sound is just the air particles vibrating and when the vibrating air molecules hit the window, they cause it to rattle. Lightning usually strikes the highest point and the most positively charged area. This is becuz lightning looks for the easiest way out of air. A high place means it has to travel less distance...
480333
natural LIGHTING comes from the sun,\notherwise, usually from an electric light bulb\n\nHowever, LIGHTNING, is a dual attraction between the sky and the ground, but physically speaking the negative charge in the sky is seeking out a positive charge on the ground, the LIGHTNING comes FROM THE SKY.\nHowever, you may not often see this and since there is a return of the lightning energy back up to the sky, (to balance the energy) so if you look after the sound of thunder you are seeing the return.
176989
electric charges go from ground to sky. The lightning is the effect (also the thunder) of such traveling charges.
108122
http://science.howstuffworks.com/lightning.htm
183433
Try:\nhttp://science.howstuffworks.com/lightning.htm\nAlso:\nhttp://science.howstuffworks.com/question182.htm\nand\nhttp://science.howstuffworks.com/question646.htm
15170
Lightning creates thunder, by rapidly heating the surrounding air. The heated air expands explosively and compresses the air immediately around the heated area.
548407
Yeah, it does...The truth is, lightning tries to find the shortest distance to ground (The Earth). Although the odds are favorable that lightning won't strike the same place twice, there is nothing in nature to prevent it. It can strike 3 or 4 times in the same spot.
157859
The first process in the generation of lightning is the forcible separation of positive and negative charge carriers within a cloud or air. The mechanism by which this happens is still the subject of research, but one widely accepted theory is the polarisation mechanism. This mechanism has two components: the first is that falling droplets of ice and rain become electrically polarised as they fall through the atmosphere's natural electric field, and the second is that colliding ice particles become charged by electrostatic induction. Once charged, by whatever mechanism, work is performed as the opposite charges are driven apart and energy is stored in the electric fields between them. The positively charged crystals tend to rise to the top, causing the cloud top to build up a positive charge, and the negatively charged crystals and hailstones drop to the middle and bottom layers of the cloud, building up a negative charge. Cloud-to-cloud lightning can appear at this point. Cloud-to-ground lightning is less common. Cumulonimbus clouds that do not produce enough ice crystals usually fail to produce enough charge separation to cause lightning.\n\nWhen sufficient negatives and positives gather in this way, and when the electric field becomes sufficiently strong, an electrical discharge occurs within the clouds or between the clouds and the ground, producing the bolt. It has been suggested by experimental evidence that these discharges are triggered by cosmic ray strikes which ionise atoms, releasing electrons that are accelerated by the electric fields, ionising other air molecules and making the air conductive by a runaway breakdown, then starting a lightning strike. During the strike, successive portions of air become conductive as the electrons and positive ions of air molecules are pulled away from each other and forced to flow in opposite directions (stepped channels called step leaders). The conductive filament grows in length. At the same time, electrical energy stored in the electric field flows radially inward into the conductive filament.\n\nWhen a charged step leader is near the ground, opposite charges appear on the ground and enhance the electric field. The electric field is higher on trees and tall buildings. If the electric field is strong enough, a discharge can initiate from the ground. This discharge starts as positive streamer and, if it develops as a positive leader, can eventually connect to the descending discharge from the cloud.\n\nLightning can also occur within the ash clouds from volcanic eruptions[1],[2], or can be caused by violent forest fires which generate sufficient dust to create a static charge.\n\nA bolt of lightning usually begins when an invisible negatively charged stepped leader stroke is sent out from the cloud. As it does so, a positively charged streamer is usually sent out from the positively charged ground or cloud. 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. This "return stroke" is the most luminous part of the strike, and is the part that is really visible. Most lightning strikes usually last about a quarter of a second. Sometimes several strokes will travel up and down the same leader strike, causing a flickering effect. This discharge rapidly superheats the leader channel, causing the air to expand rapidly and produce a shock wave heard as thunder.\n\nIt is possible for streamers to be sent out from several different objects simultaneously, with only one connecting with the leader and forming the discharge path. Photographs have been taken on which non-connected streamers are visible such as that shown on the right.\n\nThis type of lightning is known as negative lightning because of the discharge of negative charge from the cloud, and accounts for over 95% of all lightning.\n\nAn average bolt of negative lightning carries a current of 30 kiloamperes, transfe
356764
The earth is actually, as a whole, a conductor, mostly because there's a lot of earth to be a source and sink of charge. That's why many high power appliances have a third prong to plug into the wall called a "ground" (the round one below the the two flat prongs). That does actually connect into the earth. That way, if there is a malfunction, the current flows done to the earth, rather than you (which generally is not fun).\n\nIf the earth were a dielectric, current wouldn't flow at all to the earth, and so the current would have to flow somewhere else (possibly you).
344047
The cause of lightning is still somewhat mysterious.  The leading theories state that an interaction between updrafts, rain droplets, and ice crystals in a thunderstorm separates positive from negative charges, such that positive charges concentrate at the top of the cloud, and negative charges at the bottom.  This negative charge in the cloud base induces a positive charge in the ground; lightning is an attempt to equalize this charge.\n\nThunder is basically a kind of explosion of air; it's what happens when the air the lightning passes through is violently heated and expands.  The reason thunder takes several seconds is because we hear thunder produced all along the lightning channel, which may be some miles long.
93456
Some clouds contain +ve charge & some contain -ve. When both clouds come together in contact, they produce electricity which is the lightning.......
790168
Lightening (which causes the thunder) is caused by a static electrical charge build up inside very high clouds. The static build up is caused by the collision and rubbing of small ice particles way up in the clouds. If these particles get big enough they will fall down and depending on the temperature outside will either melt into rain, or could initiate crystal formation (snow).\n\nSo you see, there is nothing about whether its rain or snow that effects the mechanism of lightning generation. The reason that it is less common in the winter is that in order to produce the very high lightning generating clouds (anvil-topped cummilonimbus [sorry if spelt wrong!]) it requires very strong updrafts - This is more likely in the summer when the hot sun beating down heats air rapidly so it shoots up fast. But there are conditions in winter that can have the same effect (like collision between warm and cold fronts).
174590
Sheet lightning goes from cloud to cloud.  Lightning is caused when electrical charge accumulates within clouds.  When fork lightning happens, the charge accumulated in a cloud is discharged to the ground.  When sheet lightning occurs, two different cloud masses accumulate opposite changers until they discharge.\n\nThe voltage required to discharged is directly related to the distance between objects and the dielectric constant of the medium (i.e. air).