Researchers find unusual phenomenon in clouds triggers lightning flash

Posted: April 11, 2019 by oldbrew in atmosphere, Clouds, research, weather
Tags:


As the professor quoted below says: “Despite over 250 years of research, how lightning begins is still a mystery.” Tesla had a few ideas though (video).

In a first-of-its-kind observation, researchers from the University of New Hampshire Space Science Center have documented a unique event that occurs in clouds before a lightning flash happens, says Phys.org.

Their observation, called “fast negative breakdown,” documents a new possible way for lightning to form and is the opposite of the current scientific view of how air carries electricity in thunderstorms.

“This is the first time fast negative breakdown has ever been observed, so it’s very exciting,” said Ningyu Liu, professor of physics. “Despite over 250 years of research, how lightning begins is still a mystery. The process was totally unexpected and gives us more insight into how lightning starts and spreads.”

Their finding, published in the journal Nature Communications, is another step toward answering the question of how lightning begins.

Recently, the problem of lightning initiation seemed to be solved with the discovery of “fast positive breakdown” of air, which matched the theory long held by lightning researchers.

Fast positive breakdown involves the downward development of a pathway in the cloud, moving from the positive charge at the top of the cloud to the negative charge in the middle of the cloud. The pathway forms at one-fifth the speed of light and can trigger lightning.

However, the newly reported observation of fast negative breakdown shows that an upward pathway—going in the opposite direction and just as fast—can be created in a thundercloud, indicating there’s another way to start electricity in the air.

Ultimately, this provides scientists with a new view of what’s possible inside a storm cloud.

“These findings indicate that lightning creation within a cloud might be more bi-directional than we originally thought,” said Julia Tilles, a doctoral candidate in the UNH Space Science Center.

Full report here

Comments
  1. oldbrew says:

    Step Leaders

    Once the ionization process begins and plasma forms, a path is not created instantaneously. In fact, there are usually many separate paths of ionized air stemming from the cloud. These paths are typically referred to as step leaders.

    https://science.howstuffworks.com/nature/natural-disasters/lightning3.htm

    The paths aren’t straight due to variations in electrical resistance, i.e. the step leaders look for least resistance. An analogy would be water flow of rivers, but vastly speed up.

    Click on the blog pic – the lightning paths look a lot like a river with tributaries.
    Q: If it was a river, which direction would you expect the flow to be, judging from the picture? 😉

  2. oldbrew says:

    The first two (nos. 10 and 9) are related to lightning.

  3. ivan says:

    oldbrew, way back in the dim and distant past I was taught in my physics class that the current path in a lightning strike was from ground to clouds. Is that the answer you were looking for in your first post?

  4. oldbrew says:

    ivan – the visible evidence seems open to that interpretation, yes.

    But nobody knows it all – as the professor said:
    “Despite over 250 years of research, how lightning begins is still a mystery.”
    – – –
    Just read this…
    Types of Strikes and Types of Lightning

    Cloud to ground -Discussed previously
    Ground to cloud -The same as above with the exception that usually a tall, earth-bound object initiates the strike to the cloud
    Cloud to cloud – Also the same mechanics as discussed above except the strike travels from one cloud to another

    https://science.howstuffworks.com/nature/natural-disasters/lightning6.htm

  5. oldbrew says:

    How lightning initially forms is still a matter of debate: Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, and atmospheric pressure) to the impact of solar wind and energetic particles.
    . . .
    In an average thunderstorm, the energy released amounts to about 10,000,000 kilowatt-hours (3.6×1013 joule), which is equivalent to a 20-kiloton nuclear warhead. A large, severe thunderstorm might be 10 to 100 times more energetic.

    https://en.wikipedia.org/wiki/Atmospheric_electricity#Thunderstorms_and_lightning

    Where does all that electrical energy come from?

  6. oldmanK says:

    Quote: “In an average thunderstorm, the energy released amounts to about 10,000,000 kilowatt-hours (3.6×1013 joule), which is equivalent to a 20-kiloton nuclear warhead.”

    I tend question that. I have twice seen the effect on a carob tree. No different than what I once did with half a stick of dynamite. If there is that amount of energy, then where is most of it released? Light energy, -yes- , a fair amount which as I’m suspecting, drives a pulse from the solar panel inverters enough to trip all the ELCB in the vicinity.

  7. oldbrew says:

    The same Wikipedia piece also says:

    An average bolt of lightning carries a negative electric current of 40 kiloamperes (kA) (although some bolts can be up to 120 kA), and transfers a charge of five coulombs and energy of 500 MJ, or enough energy to power a 100-watt lightbulb for just under two months.

    The whole thunderstorm is obviously a lot of those.
    – – –
    Venezuela’s Mysterious Catatumbo Lightning Phenomenon Vanishes for Months, Then Reappears

    Catatumbo lightning phenomenon mysteriously disappeared for months in 2010.

    “They have no idea that this lightning flashing around all night is something unique,” said Alan Highton, a tour operator based on Lake Maracaibo who lives part-time with the indigenous people. “It doesn’t occur anywhere else in the world.”
    . . .
    For a several months starting January 2010, not one lightning bolt was seen, sparking concern it was gone forever. Then, as mysteriously as it had stopped, it began again, as proven from NASA satellite data.

    There are lots of theories on why the lightning stopped and then started again.

    https://abcnews.go.com/International/venezuelas-mysterious-catatumbo-lightning-phenomenon-vanishes-months-reappears/story?id=14120203

    The Guardian had a drought theory…
    Drought extinguishes Venezuela’s lightning phenomenon

    Lake Maracaibo left in darkness as drought caused by El Niño disrupts weather patterns that cause constant lightning storms
    . . .
    The last time the phenomenon vanished was in 1906 after a catastrophic 8.8-magnitude earthquake off the coast of Ecuador and Colombia unleashed a tsunami. The lightning returned three weeks later.

    https://www.theguardian.com/world/2010/mar/05/venezuela-lightning-el-nino

  8. oldbrew says:

    2016 study:
    Seasonal prediction of lightning activity in North Western Venezuela: Large-scale versus local drivers

    Highlights

    • First predictability study of lightning density rate at seasonal scale.

    • Most seasonal lightning activity in the Lake Maracaibo Basin is related to a highly predictable regional mode of variability.

    Best identified predictors are sea-surface temperature and meridional transport of Convective Available Potential Energy. [bold added]

    • Predictive skill is higher than typical values for rainfall amounts in the region, and it is similar for winter and autumn.

    https://www.sciencedirect.com/science/article/pii/S0169809516000041
    – – –
    How North Sea helicopters cause lightning to strike
    BBC Scotland reporter
    9 February 2015

    Pilots whose helicopters have been hit by lightning have reported there was no sign of it present in the area before they were struck.

    Forecasters now know the negatively-charged helicopter acts as a conductor for the lightning, aiding its passage to the earth.
    . . .
    The CAA has received notification of six lightning strikes on offshore helicopters since 2010.

    https://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-31206363

    This is a form of ‘triggered lightning’.
    https://www.nssl.noaa.gov/education/svrwx101/lightning/types/

  9. ivan says:

    Where does all that electrical energy come from?

    A very good question to which I would add can we harness it in a useful way? In fact it would be a good research project for all those chasing ‘pie in the sky’ battery enhancements. If they cracked that it would put all the toy bird mincers out of business and save the various countries power grids from being destroyed.

  10. oldbrew says:

    Convective available potential energy

    In meteorology, convective available potential energy (commonly abbreviated as CAPE),[1] is the amount of energy a given mass of air (called an air parcel) would have if lifted a certain distance vertically through the atmosphere. CAPE is effectively the positive buoyancy of an air parcel and is an indicator of atmospheric instability, which makes it very valuable in predicting severe weather. It is a form of fluid instability found in thermally stratified atmospheres in which a colder fluid overlies a warmer one. An air mass will rise if it is less dense than the surrounding air (its buoyant force is greater than its weight). This can create vertically developed clouds due to the rising motion, which could lead to thunderstorms.

    Read more: https://en.wikipedia.org/wiki/Convective_available_potential_energy

    Significance to thunderstorms
    https://en.wikipedia.org/wiki/Convective_available_potential_energy#Significance_to_thunderstorms

  11. oldbrew says:

    Why lightning often strikes twice: Highly charged particles in thunderclouds aren’t all released at the same time

    Researchers from the Groningen University in The Netherlands used LOFAR

    LOFAR is made up of thousands of antennas spread across northern Europe
    Lightning discharges produce bursts in the very high frequency radio band
    Experts detected ‘needle’ structures inside the channels of lightning strikes
    Electrical charges from the first strike inside these can then trigger a second

    By YUAN REN FOR MAILONLINE
    PUBLISHED: 18:00, 17 April 2019

    https://www.dailymail.co.uk/sciencetech/article-6932787/Highly-charged-particles-thunderclouds-arent-released-time.html

  12. Adventure Time says:

    There is also discovered recently 27 day cycle in regular activity level of lightning. The postulate is that solar winds influence its activity, relative to the frame of reference the earth is in, thus 27 day turns of the sun corresponding to 27 turns of the earth, some how influences, the activity of thunder. But this result is only valid over large area.

    I believe the tracts the thunder runs through, at discharge are influenced by solar winds and the cosmic rays.

    https://www.ann-geophys.net/35/583/2017/angeo-35-583-2017.pdf
    there are many more article related to this phenomenon.

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