Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lightning really does strike more than twice

16.01.2003


NASA-funded scientists have recently learned that cloud-to-ground lightning frequently strikes the ground in two or more places and that the chances of being struck are about 45 percent higher than what people commonly assume.




Recently, William C. Valine and E. Philip Krider in the Institute of Atmospheric Physics at the University of Arizona, co-authors of the study, took to the field using video and other technology to study lightning, which is one of the biggest weather-related killers in the United States, superseded only by extreme heat and flooding.

They recorded 386 cloud-to-ground (CG) lightning flashes on videotape during the summer of 1997 in Tucson, Arizona. They found that within their sample of 386 flashes, 136 flashes (35 percent) struck the ground in two or more places that were separated by tens of meters (yards) or more. There were a total of 558 different strike points; therefore, on average, each cloud-to-ground flash struck the ground in 1.45 places.


"Most people assume that lightning strikes in only one place. In this research, we’ve documented that lightning definitely strikes more than one place about a third of the time," Krider said. "If you want to quantify the chances of being struck by lightning, they are about 45 percent higher than the number of flashes because, on average, there are about 1.45 strike points per CG flash."

Within that group of 136 flashes, termed "multiple channel flashes," 88 had two or more separate and distinct channels (or paths) between the cloud base and the ground. Thirty-seven of the flashes forked below the cloud base and struck ground in two or more places. Eleven flashes exhibited both types of behavior. In other words, during the observations in Arizona, for every fork below the cloud there were approximately twice as many flashes that had separate and distinct paths, a ratio that is consistent with previous measurements in Florida.

Valine and Krider also confirmed that after an initial stroke, 67 percent of the new strike points were produced by the second stroke in the flash, rather than the third or fourth stroke. In other words, if any subsequent stroke is going to strike a place different from the first stroke, it is usually the second stroke that does so. The third and fourth strokes usually follow the same path as the second stroke.

Lightning occurs when there is a discharge of electricity between large volumes of excess positive and negative charge that accumulate in thunder clouds. Lightning most commonly occurs in thunderstorms, but it also can occur in snowstorms, sandstorms, in the ejected material over volcanoes. Most lightning takes place within or between clouds; on average, only about one-third of all discharges actually strike the ground. The peak temperature in a lightning channel is around 60,000 degrees Fahrenheit, or about 5 times hotter than the surface of the Sun.

According to the National Weather Service, lightning causes an average of 93 deaths and 300 injuries in the United States each year. The National Severe Storms Laboratory recommends that a safe distance from a previous flash is at least 10 to 13 km (6 to 8 miles) as opposed to the 3 to 5 km (2-3 miles) that experts had previously advised.

The article appears in the latest print issue of the American Geophysical Union’s Journal of Geophysical Research - Atmospheres, and publication of the results was funded entirely by NASA.

For additional information and images, see: http://www.gsfc.nasa.gov/topstory/2003/0107lightning.html

For more information about lightning and lightning safety, see: http://www.erh.noaa.gov/er/cae/svrwx/ltg.htm

The National Severe Storms Laboratory on Lightning: http://www.nssl.noaa.gov/researchitems/lightning.shtml

Global Hydrology and Climate Center (GHCC) Lightning Team:
http://thunder.msfc.nasa.gov/

Rob Gutro | EurekAlert!
Further information:
http://www.gsfc.nasa.gov/topstory/2003/0107lightning.html
http://www.erh.noaa.gov/er/cae/svrwx/ltg.htm
http://www.nssl.noaa.gov/researchitems/lightning.shtml

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Researchers devise microreactor to study formation of methane hydrate

23.08.2017 | Materials Sciences

ShAPEing the future of magnesium car parts

23.08.2017 | Automotive Engineering

New insights into the world of trypanosomes

23.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>