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Lightning leaders to converge on Alabama

International conference set for June

May 24, 1999: By the time you finish reading this sentence, lightning will have struck more than 100 times across the Earth. Each delivers about 1 trillion watts of electricity in manner of microseconds. The highly conductive lightning channel heats the air to over 15,000 deg. C (27,000 deg. F), which is almost three times the surface temperature of the sun.

Lightning also is one of the most beautiful and mysterious events in nature, something to admire, from a safe distance - and to study in detail.

Right: Look but don't touch (meaning stay inside; don't stand in the open or near trees or power lines). Lightning is as deadly as it is beautiful. Credit: Chuck Clark, NOAA.

The Global Hydrology and Climate Center (GHCC) will host the 11th quadrennial International Conference on Atmospheric Electricity, June 7-11 at Guntersville State Park in north Alabama. Scientists attending this conference study thunderstorms, lightning and other electrical properties of the atmosphere. This will be the first time that the conference has been held in the Southeast.

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"Traditionally, this conference has been hosted by a group that is active in the field of atmospheric electricity or lightning research," said Dr. Hugh Christian, one of the lead lightning scientists at the GHCC. The GHCC fits that criterion since its scientists are among the world leaders in the field of atmospheric electricity and revolutionized the field of spaced-based lightning observations from well before the GHCC was founded in 1994.

Left: A frame from TV images taken aboard the Space Shuttle (STS-35; April 28, 1990) shows lightning outshining city lights - and a sprite reaching for the top of the atmosphere. (NASA)

Beginning in 1980, scientists from this group have studied lightning and thunderstorm from NASA's ER-2 high altitude aircraft and later from the Space Shuttle. In the Mesoscale Lightning Experiment, the Shuttle 's payload bay cameras observed lightning on the nightside of the Earth during crew sleep periods.

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More recent observations have been made using the Marshall-developed Optical Transient Detector (OTD) on MicroLab 1 (launched April 3, 1995) and the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM; launched Nov. 28, 1997). Christian is the principal investigator for both instruments.

NASA and the Air Force continue to have a deep interest because of the potential for lightning to destroy rockets: their metal bodies and long conducting trail of hot gas can readily trigger lightning flashes.

Despite its fascinating nature and the damage and death it causes, only a relatively small number of groups around the world study lightning.

Lightning distribution as seen by the Optical Transient Detector aboard MicroLab 1 during September 1995-August 1997. (NASA/GHCC)

"The U.S. is one of the most active countries in the field of Atmospheric Electricity," Christian said. "Japanese scientists also are active. However, it tends to concentrate on the physics of the lightning event, perhaps because its power industry plays such an active role. In the United States, there is also much interest in the meteorological aspects of the science."

In addition, groups from around the world including scientists from Japan, Russia, Germany, France, Sweden, China and India are actively involved in the field. The conference will be large, with scientists from 28 countries in attendance. Christian expects more than 200 scientists will turn out to present papers.

Web Links
International Conference on Atmospheric Electricity web page has the agenda plus details on how to get to Guntersville.
Lightning Imaging Sensor, an informative 2-page brochure about the LIS and its mission, is available as a 157K Acrobat PDF.
Lightning and Atmospheric Research
at the Global Hydrology and Climate Center.
Lightning likes land (May 19, 1998): Report on the first three months of LIS data.
Lightning detector watches storm that spawned spawned the deadly February 1998 Florida tornadoes (April 2, 1998): Lightning sensors in space and on the ground are showing the value of having a space-based network of sensors that could spot and track storms which are likely to spawn tornadoes..
LIS launched (Nov. 28, 1997): Includes a description of the LIS and its mission
One of the topics they will hear is research indicating that lightning has the potential for providing excellent real-time information about the energy inside the storms. The classic anvil and the "overshooting turret" cloud formations are good indicators of convection. However, these cloud formations provide little insight into what is happening deep in the heart of the cloud and the anvils survive well after the convective activity has ended.

"We think that lightning responds very rapidly to what is happening in the center of clouds with electrical energy being generated within minutes of changes in convective intensity," Christian said. The ability to monitor closely what is happening inside the clouds could be a valuable tool for predicting what might happen next - including the potential for a tornado.

Recent advances in radar, including NEXRAD, have improved the weather forecaster's ability to tell if a tornado is spinning out of a storm cell, but they still lag in their ability to measure the vertical velocity of these storms, which are important clues to the overall puzzle. Establishing multiple operational Doppler radar networks around the nation or placing fleets of weather radars in orbit is impractical.

Right: Many scientists view lightning as the most visible (and dangerous) part of a much larger global electrical circuit in which the ground itself is, well, the ground plane. (NASA)

But watching for lightning from space might be a viable alternative, Christian said. His team has been studying designs for a lightning mapping sensor that would be added to weather satellites in geostationary orbit. The sensor would watch the entire continent and focus in on areas where lightning activity seems to be sharply increasing and decreasing.

A sudden jump in activity may be the clue that scientists have been seeking for detecting an intensifying storm that might be a precursor to tornadoes. This dramatic increase in lightning, signifying intensification of the storm's vertical motion is generally followed by a sharp decrease, suggesting collapse.

On April 17, 1995, the OTD observed a steady rise in lighting activity in a supercell storm over Oklahoma. Just before the spacecraft passed out of view of the storm, the lightning rates dropped sharply. A few minutes later, a tornado was observed descending out of the storm.

Left: A tornado aims for Dimmet, Texas. (NOAA)

The linkage is that strong upward convection leads to high lightning rates and increased vorticity. Then the convection collapses and generates downdrafts, leading to a sharp decrease in the lightning and setting the conditions for the onset of a tornado.

Validation of this effect could enhance warning capabilities with space-based lightning sensors providing up to 10 extra minutes more warning time for severe weather intensification and tornadoes.

In addition to this tantalizing discovery, the GHCC's lightning team has found that lightning loves land. Maps of global lightning frequency shows that lightning occurs most often in storms over land. Further, they have hypothesized that lightning loves land because the heating of the continents creates stronger convection.

 

Lightning likes land: Data from the Lightning Imaging Sensor shows that most lightning strikes occur over land where the ground can warm the air more effectively. This map is covers to the latitudes (35 deg. N to 35 deg S) overflown by the Tropical Rainfall Measuring Mission carrying the LIS. Links to 937x224-pixel, 37K GIF. (NASA/GHCC)

Space-based observations of lightning will be only one of dozens of topics covered at at the Atmospheric Electricity Conference.

Several papers will be presented on sprites, the tantalizing flashes of light that dance high over the tops of storm, seemingly into space. While the physics of this phenomenon is not understood, it is possible that sprites play important roles in the global electrical circuit and upper atmospheric chemistry. Other papers will cover the 3-dimensional structure of lightning, the physics of charge generation and lightning initiation, and studies of lightning variations with weather phenomena such as El Nino. Sessions will be dedicated to lightning characteristics, lightning detection and protection, thunderstorm characteristics, fair weather electricity, global lightning and lightning chemistry.

Lightning Stories from this conference

Human Voltage (June 18, 1999) Scientists discuss biology, safety, and statistics of lightning strikes.
News shorts from Atmospheric Electricity Conference
(June 16, 1999) Poster papers on hurricanes and tornadoes summarized.
Soaking in atmospheric electricity
(June 15, 1999) 'Fair weather' measurements important to understanding thunderstorms.
Lightning position in storm may circle strongest updrafts (June 11, 1999) New finding could help in predicting hail, tornadoes
Lightning follows the Sun
(June 10, 1999) Space imaging team discovers unexpected preferences
Spirits of another sort
(June 10, 1999) Thunderstorms generate elusive and mysterious sprites.
Getting a solid view of lightning (June 9, 1999): New Mexico team develops system to depict lightning in three dimensions.
Learning how to diagnose bad flying weather (June 8, 1999): Scientists discuss what they know about lightning's effects on spacecraft and aircraft.
Three bolts from the blue
(June 8, 1999): Fundamental questions about atmospheric electricity posed at conference this week.
Lightning Leaders Converge in Alabama (May 24, 1999): Preview of the 11th International Conference on Atmospheric Electricity.
What Comes Out of the Top of a Thunderstorm? (May 26, 1999): Gamma-rays (sometimes).

Lightning research at NASA/Marshall and the Global Hydrology and Climate Center.

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For more information, please contact:
Dr. John M. Horack , Director of Science Communications
Author: Dave Dooling
Curator: Linda Porter
NASA Official: Gregory S. Wilson