Everyone has seen lightning and thought it was powerful. The reason why lightning proceeds in a series of steps from the thundercloud to the earth below remains a mystery.
There are a few textbooks on lightning, but they don't explain how lightning can travel over kilometers.
An explanation is provided by my new research.
The singlet delta oxygen molecule is created by the intense electrical fields in thunder clouds.
A millionth of a second is the time it takes for a molecule and electron to build up.
There is a pause at the end of the step as the build-up continues, followed by a bright, flashing leap. The process is repeated many times.
There has been an increase in extreme weather events. Knowing how a lightning strike is initiated can help us protect ourselves.
The use of eco-friendly materials in aircraft increases the risk of lightning damage, so we need to look at additional protection.
thunderclouds with an electric potential of millions of volts connect to the earth and cause lightning strikes. The ground and the sky have a temperature of tens of thousands of degrees.
There are a lot of details not seen by the naked eye. There are usually four or five people in the sky. They are on an irregular path.
The lightning strike begins when the first leader reaches the earth. The other leaders are no longer alive.
Fifty years ago high-speed photography showed more complexity. The leaders make their way down from the cloud in a series of steps. It takes a millionth of a second for the steps to become bright.
The previous steps remain dark after a further 50 millionths of a second.
There are steps that are unexplained. The dark periods between steps can be confusing. The steps are not connected to the cloud.
Understanding what happens when an electron hits an oxygen molecule is the answer to these questions.
The molecule is excited by the electron into the singlet Delta state. It's not perfectly stable, but it doesn't fall into a lower energy state for a while.
electrons are removed from negative oxygen ion in this singlet Delta state. The electrons are attached to the oxygen molecule and replace the ion.
The air can conduct electricity if it has more than 1 percent of the oxygen in it.
As the metastable states are created to detach a lot of electrons, the lightning steps occur. The density of metastable states is increasing.
The step can conduct electricity after 50 millionths of a second, and the electrical potential at the tip of the step increases to roughly that of the cloud.
The excited molecule formed a column all the way to the cloud. There is no need for an electric field or emission of light in the column.
It is important for the design of protection for buildings and aircraft to understand lightning formation.
It is rare for lightning to hit people but buildings are hit a lot.
When a tree is struck by lightning, the tree's steam creates pressure and splits the trunk.
Water from the rain seeped into the concrete boil when lightning struck the corner of the building. The risk of deadly collapses is created by the pressure blowing off the entire corner of the building.
A lightning rod is a thick wire that is attached to the top of a building and connects to the ground. The electric charge is attracted by it. The building is saved from being damaged by being directed through the wire.
The uncertain factor is how many Franklin rods are needed on each building.
Shelter sheds are not protected. The structures are usually made from galvanized iron and supported by wooden posts.
Shelters that protect against lightning should be earthed, according to the new version of Standards Australia.
John Lowke is a professor of physics.
Under a Creative Commons license, this article is re-posted. The original article is worth a read.
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