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and other technology to study lightning, which is one of the biggest weather-related killers in the United States, superseded only by extreme heat and flooding.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

More articles from Earth Sciences:

nachricht Upwards with the “bubble shuttle”: How sea floor microbes get involved with methane reduction in the water column
27.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

nachricht An international team including scientists from MARUM discovered ongoing and future tropical diversity decline
26.05.2020 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Small Protein, Big Impact

In meningococci, the RNA-binding protein ProQ plays a major role. Together with RNA molecules, it regulates processes that are important for pathogenic properties of the bacteria.

Meningococci are bacteria that can cause life-threatening meningitis and sepsis. These pathogens use a small protein with a large impact: The RNA-binding...

Im Focus: K-State study reveals asymmetry in spin directions of galaxies

Research also suggests the early universe could have been spinning

An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...

Im Focus: New measurement exacerbates old problem

Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.

Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

Why developing nerve cells can take a wrong turn

04.06.2020 | Life Sciences

The broken mirror: Can parity violation in molecules finally be measured?

04.06.2020 | Physics and Astronomy

Innocent and highly oxidizing

04.06.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>