Does lightning travel upwards or downwards?

Question

Does lightning travel upwards or downwards?

Answer 1

Most of the lightning's length comes downward. There is a short bit of the lightning that comes up from the ground to meet the long bit.  They are called "streamers". On some photos you can see several of those short one coming up and trying to meet the long bit, but only one of them does it. Here's a video of one that didn't make it to the main lightning - http://www.youtube.com/watch?v=4CezC0xZF...

Answer 2

both.

Answer 3

Both, sorta, but downwards is the best choice.

Because of the way that water droplets distribute themselves in a cloud, the top of the cloud is positive and the bottom is negative. When a spark jumps within the cloud, you get intra-cloud lightning.

Since the bottom of the cloud is negative, it has a HUGE excess of electrons. Those electrons create an electric field through the air that pushes on the matter below, such as a tree, a metal tower, or a park ranger. Because negative (electrons) repels negative (other electrons), the cloud pushes all of your electrons down into the earth, giving you a net positive charge (induction).

Opposites attract, and a spark jumps. A spark consists of a path of freely flowing electrons in plasma. electrons will always move from negative to positive (because they are negative, so they are repelled by the negative pole). That means that they move from the cloud to the ground. Down.

However, sometimes it will appear that lightning strikes up, because the negative in the cloud actually "pulls" a bolt of positive charge out of you and into the cloud through the air. Although this event, called a positive streamer, moves upwards, the current still flows downwards.

Answer 4

From the ground, up.

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Answer 5

That is under debate.

I was taught it strikes up from the ground.  Ben Franklin thought it stroke downward.  It strikes from cloud to cloud normally so it can't always be just from the ground.  Maybe it is both.

It seems come from the sky, but if the negative electrical charge is in the ground then it comes from the ground.  Sky to sky lighting and the lightning that hits air planes frequently comes from the sky, but not all lightning may do that.

Lightning is static electricity on the scale of the earth.  Imagine rubbing a carpet that is 14 square miles with a foot equally as big and you have an idea of why the voltage is so high.

According to Wikipedia:  http://en.wikipedia.org/wiki/Lightning

"Lightning is an atmospheric discharge of electricity, 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, and can reach temperatures approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into petrified lightning, known scientifically as glass channels or fulgurites which are normally hollow and can extend some distance into the ground . There are over 16 million lightning storms every year.

Lightning can also occur within the ash clouds from volcanic eruptions, or can be caused by violent forest fires which generate sufficient dust to create a static charge.

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. Ice inside 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....

- Polarization mechanism hypothesis

The mechanism by which charge separation happens is still the subject of research, but one hypothesis is the polarization mechanism, which has two components:

   1. Falling droplets of ice and rain become electrically polarized as they fall through the atmosphere's natural electric field;

   2. Colliding ice particles become charged by electrostatic induction.

Ice and supercooled water are the keys to the process. Violent winds buffet tiny hailstones as they form, causing them to collide. When the hailstones hit ice crystals, some negative ions transfer from one particle to another. The smaller particles lose negative ions and become positive and the larger more massive particles gain negative ions and become negative.

- Electrostatic induction hypothesis

Another hypothesis is that opposite charges are driven apart by the above mechanism and energy is stored in the electric field between them. Cloud electrification appears to require strong updrafts which carry water droplets upward, supercooling them to between -10 and -20 °C. These collide with ice crystals to form a soft ice-water mixture called graupel. The collisions result in a slight positive charge being transferred to ice crystals, and a slight negative charge to the graupel. Updrafts drive lighter ice crystals upwards, causing the cloud top to accumulate increasing positive charge. The heavier negatively charged graupel falls towards the middle and lower portions of the cloud, building up an increasing negative charge. Charge separation and accumulation continue until the electrical potential becomes sufficient to initiate lightning discharges, which occurs when the gathering of positive and negative charges forms a sufficiently strong electric field.

There are several additional hypotheses for the origin of charge separation.

- Leader formation

As a thundercloud 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 thundercloud. 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 electric 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. 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...

"- Gurevich's runaway breakdown theory

Main article: Runaway breakdown:  http://en.wikipedia.org/wiki/Runaway_bre...

A theory of lightning initiation, known as the "runaway breakdown theory", proposed by Aleksandr Gurevich of the Lebedev Physical Institute in 1992 suggests that lightning strikes are triggered by cosmic rays which ionize atoms, releasing electrons that are accelerated by the electric fields, ionizing other air molecules and making the air conductive by a runaway breakdown, then "seeding" a lightning strike."

And "Note

    Positive lightning (a rarer form of lightning that originates from positively charged regions of the thundercloud) does not generally fit the pattern."

To study lightning in Florida a college shoot rockets up into thunder clouds trailing a wire that is grounded so the bolt travels downward.  Then there is ball lightning:  http://en.wikipedia.org/wiki/Ball_lightn... that doesn't travel up or down but around.

Sorry I couldn't give you a definite answer, but even the best brains aren't sure.  Cancer was once thought to come from one cause because it is one disease with one effect, but now we know many things can cause cancer and you can even have a genetic condition that makes it more likely.  Lightning is pretty complex and we haven't figured it all out yet.

Answer 6

technically lightning does both. Lightning occurs because of a difference in charge between a storm cloud and the ground.  In a cloud-to-ground strike, an electric charge from the cloud starts coming down, and gets about 2/3 the way toward the ground. At that point, a return stroke of opposite charge will race up from the ground and meet the original charge, creating a channel where the electricity can flow back and forth several times until the charges have been neutralized

Answer 7

Both. It has often been observed that lightning shoots up from the ground to meet up with a fork of lightning coming down.

Answer 8

Upwards. I believe

Answer 9

it travels upwards, i've seen it...<^><..

Answer 10

Both.

Cloud-to-ground

Cloud-to-ground lightning is a great lightning discharge between a cumulonimbus cloud and the ground initiated by the downward-moving leader stroke. This is the second most common type of lightning, and poses the greatest threat to life and property of all known types.

Ground-to-cloud lightning

Ground-to-cloud lightning is a lightning discharge between the ground and a cumulonimbus cloud from an upward-moving leader stroke.

Answer 11

both, a small thin invisible lightning bolt first travels upwards, once it touches the cloud the path for the greater charge in the clouds has been created and so a sudden discharge of electric travels downwards along the path , this is the bright loud one.