Central Africa is the area of the world where lightning strikes most frequently. Lightning is an electrical discharge caused by imbalances between storm clouds and the ground, or within the clouds themselves.
Most lightning occurs within the clouds. Other visible bolts may appear as bead, ribbon, or rocket lightning. During a storm, colliding particles of rain, ice, or snow inside storm clouds increase the imbalance between storm clouds and the ground, and often negatively charge the lower reaches of storm clouds. Objects on the ground, like steeples, trees, and the Earth itself, become positively charged—creating an imbalance that nature seeks to remedy by passing current between the two charges.
This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash. Each bolt can contain up to one billion volts of electricity. A typical cloud-to-ground lightning bolt begins when a step-like series of negative charges, called a stepped leader, races downward from the bottom of a storm cloud toward the Earth along a channel at about , mph , kph.
Each of these segments is about feet 46 meters long. When the lowermost step comes within feet 46 meters of a positively charged object, it is met by a climbing surge of positive electricity, called a streamer, which can rise up through a building, a tree, or even a person.
When the two connect, an electrical current flows as negative charges fly down the channel towards earth and a visible flash of lightning streaks upward at some ,, mph ,, kph , transferring electricity as lightning in the process. Some types of lightning, including the most common types, never leave the clouds but travel between differently charged areas within or between clouds. Other rare forms can be sparked by extreme forest fires, volcanic eruptions, and snowstorms.
Ball lightning, a small, charged sphere that floats, glows, and bounces along oblivious to the laws of gravity or physics, still puzzles scientists. About one to 20 cloud-to-ground lightning bolts is "positive lightning," a type that originates in the positively charged tops of stormclouds.
Red sprites are not very easy to see. If you are far away from the actual thunderstorm and watching it at night in the absence of much light pollution, you may be able to catch a glimpse of them. Lightning sprites usually appear as a range of red visual shapes flickering in the sky. The flickers typically only last a fraction of a second. This discharge is a natural display of electrostatics, and there are specific conditions that are a requirement for lightning to occur.
Before lightning can form and strike, there must be a separation of positive and negative charges in the thundercloud. This is known as polarization and usually occurs with the tops of the clouds forming a primarily positive region, while the bottoms form a negative region. Once this has occurred, it creates an intense electrostatic field in the atmosphere. You may be wondering what causes the polarization of the different parts of the clouds in the first place.
There are a few possible mechanisms for this. Ionization or the formation of electric charges in the clouds can be caused by cosmic rays that ionize air molecules. Cosmic rays are high-energy particles from outside the solar system, and one example of these is protons. After the atoms are ionized, separation of charges occurs, which is important for lightning production. Inside a cloud, there are millions of ice particles and suspended water droplets colliding with each other in a random manner.
When clusters of water droplets join the cloud from groundwater evaporation, these collide with droplets already in the cloud. The result of this is the ripping off of electrons from the rising water droplets. Polarization of a storm cloud may also occur during freezing. At higher altitudes, rising droplets of water start to freeze and cluster together with the outer portion of the clouds being become positive and the inner portion becoming negative.
Heavier, negatively charged particles sink to the bottom of the cloud. When the positive and negative charges grow large enough, a giant spark - lightning - occurs between the two charges within the cloud. This is like a static electricity sparks you see, but much bigger. Most lightning happens inside a cloud, but sometimes it happens between the cloud and the ground.
A build up of positive charge builds up on the ground beneath the cloud, attracted to the negative charge in the bottom of the cloud.
The ground's positive charge concentrates around anything that sticks up - trees, lightning conductors, even people! The positive charge from the ground connects with the negative charge from the clouds and a spark of lightning strikes.
Go to What is lightning? Lightning is an amazing natural phenomenon. Use it to discuss the nature of electricity, charge and the transfer of electrical energy into heat, light and sound. Planet Science. Your contact with a metal doorknob—or car handle or anything that conducts electricity—presents that opportunity and the excess electrons jump at the chance. So, do thunderclouds have rubber shoes?
Not exactly, but there is a lot of shuffling going on inside the cloud. Lightning begins as static charges in a rain cloud. Winds inside the cloud are very turbulent. Water droplets in the bottom part of the cloud are caught in the updrafts and lifted to great heights where the much colder atmosphere freezes them. Meanwhile, downdrafts in the cloud push ice and hail down from the top of the cloud.
Where the ice going down meets the water coming up, electrons are stripped off. It's a little more complicated than that, but what results is a cloud with a negatively charged bottom and a positively charged top. These electrical fields become incredibly strong, with the atmosphere acting as an insulator between them in the cloud.
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