Presentation on theme: "GPL Lightning Group Florida Institute of Technology Dept. of Physics and Space Sciences."— Presentation transcript:
GPL Lightning Group Florida Institute of Technology Dept. of Physics and Space Sciences
GPL Lightning Group - Physics Dept. 2 Other Collaborators J. Dwyer, D. Barnes, E. Cramer, M. Schaal, S. Lazarus, M. Splitt, S. Arabshahi, B. Kosar, S. Sadighi, N. Liu, and H. Rassoul, Florida Institute of Technology J. Fishman and M. Briggs MSFC and U. of Alabama D. Smith University of California at Santa Cruz M. Uman, D. Jordan, D. Hill, C. Biagi University of Florida
GPL Lightning Group - Physics Dept. 3 Lightning is a giant discharge of electricity accompanied by a brilliant flash of light and a loud crack of thunder. The spark can reach over five miles (eight kilometers) in length, raise the temperature of the air by as much as 50,000 degrees Fahrenheit (27,700 degrees Celsius), and contain a hundred million electrical volts. Reference: National Geographic What is lightning?
GPL Lightning Group - Physics Dept. 4 The rapid expansion of heated air causes the thunder. Since light travels faster than sound, the thunder is heard after the lightning. If you see lightning and hear thunder at the same time, that lightning is in your neighborhood. If you see successive strokes of lightning in the same place on the horizon then you are in line with the storm, and it may be moving toward you. Reference: National Geographic What is thunder?
GPL Lightning Group - Physics Dept. 5 The odds of becoming a lightning victim in the U.S. in any one year is 1 in 700,000. The odds of being struck in your lifetime is 1 in 3,000. Reference: National Geographic
GPL Lightning Group - Physics Dept. 6 Rubber shoes will not give you any meaningful protection from lightning. Reference: National Geographic =
GPL Lightning Group - Physics Dept. 7 About 10 percent of lightning- stroke victims are killed, and 70 percent suffer serious long-term effects. About 400 people survive lightning strokes in the U.S. each year. Reference: National Geographic Lightning can kill people (3,696 deaths were recorded in the U.S. between 1959 and 2003) or cause cardiac arrest. Injuries range from severe burns and permanent brain damage to memory loss and personality change.
GPL Lightning Group - Physics Dept. 8 What happens if your car gets hit by lightning and you are inside? Answer: Nothing (as long as you are not touching the frame of the car, which includes the sides and the steering wheel) The car acts as a Faraday cage and protects you while you are inside the vehicle!
GPL Lightning Group - Physics Dept. 9 What happens if an airplane gets hit by lightning during a thunderstorm? Answer: Usually nothing!! The electrical energy travels through the metal skin of the aircraft leaving you unharmed! (new.dixie.edu)
GPL Lightning Group - Physics Dept. 10 Answers Not Known to this Day How does lightning get started with the relatively low electric field strengths inside thunderstorms? How does lightning travel through tens of kilometers of air? Why does lightning hit one object and not another? (e.g. Why did the lightning hit the tree?)
GPL Lightning Group - Physics Dept. 11 Lightning Initiation??? In 1999, Russian physicist Alex Gurevich and collaborators suggested that cosmic-ray air showers could trigger lightning. Cosmic-rays are energetic particles from space. When they strike the earths atmosphere, they create large showers of high energy particles. (www.scifun.ed.ac.uk)
GPL Lightning Group - Physics Dept. 12 Air Showers Plus Runaway Breakdown Studies have shown that, by itself, even a large air shower will not produce enough particles to significantly affect the conductivity inside the thunderstorm, making it unlikely that it will trigger lightning. One way to increase the number of energetic particles so that lightning may be triggered is to include runaway breakdown. Runaway breakdown is a kind of discharge involving very fast electrons.
GPL Lightning Group - Physics Dept. 13 Model of a 25 MeV electron moving through air at 1 atm (No electric field) No Relativistic Runaway Electron Avalanche Model of a 25 MeV electron moving through air at 1 atm in a 3 kV/cm electric field Relativistic Runaway Electron Avalanche
GPL Lightning Group - Physics Dept. 14 The International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL is the location where most of the ground-based observations take place. This facility is operated jointly by the University of Florida and Florida Tech. It is capable of measuring magnetic fields, electric fields, and other energetic emissions. We use the Thunderstorm Energetic Radiation Array (TERA) to measure the x-ray and gamma-ray emissions along with a flat plate antenna to measure the electric field. TERA is composed of 24 separate aluminum boxes designed specifically to keep light and noise out. Each box houses up to two NaI(T1)/PMT detectors with the necessary fiber optic wiring and electronic equipment to control each detector.
GPL Lightning Group - Physics Dept. 15 Instruments and Setup
GPL Lightning Group - Physics Dept. 16 Video of Rocket-triggered Lightning
GPL Lightning Group - Physics Dept. 17 Video of Rocket-triggered Lightning (slow)
GPL Lightning Group - Physics Dept. 18 Video of Rocket-triggered Lightning
GPL Lightning Group - Physics Dept. 19 Video of Rocket-triggered Lightning (slow)
GPL Lightning Group - Physics Dept. 20 X-Rays From Rocket- Triggered Lightning Dart Leaders (Dwyer et al. 2004a)
GPL Lightning Group - Physics Dept. 21 X-Rays From Natural Cloud-To-Ground Lightning (Dwyer et al. 2005) www.moonraker.com.au/techni/lightning-marine.htm
GPL Lightning Group - Physics Dept. 22 Ground Level Gamma-Ray Burst (Dwyer et al. 2004b) In 2003, a ground level gamma-ray burst was seen by rocket-triggered lightning The event fit the energy profile that was seen with other terrestrial gamma-ray flashes (TGFs)
GPL Lightning Group - Physics Dept. 23 Terrestrial Gamma-Ray Flash First discovered by Fishman et al. 1994 CGO/BATSE High energy gamma-ray flash (www.usra.edu) (Fishman et al. 1994)
GPL Lightning Group - Physics Dept. 24 Where Do TGFs Come From? 1994 – 2005: People thought Here After 2005: Here (www.holoscience.com)
July 21-23, 2009Lightning25 ADELE ADELE was mounted in the NSF/NCAR Gulfstream V operated under the HIAPER program. Missions were flown directly above low thunderstorms and to the sides of taller thunderstorms. Purpose : to detect x-ray and gamma- ray emissions from thunderstorms. Goal : to capture thousands of gammas per TGF as opposed to the dozens captured by detectors in orbit.
GPL Lightning Group - Physics Dept. 26 ADELE - Antenna Flat plate antenna measured dE/dt simultaneously with x-ray measurements
GPL Lightning Group - Physics Dept. 27 ADELE – Initial Results Glows : gamma excesses seen in the ADELE instruments. This could possibly be caused by the electric field being kept at a limiting value by a gradual runaway feedback. Surges : second to minute in length enhancements TGFs : millisecond in length; MeV energies GV flew 14 flights and was within 20 miles of lightning flashes
ADELE – Initial Results GPL Lightning Group - Physics Dept. 28 2 periods of strong 511 keV positron annihilation lines. Implies a buildup of positrons and considerable pair-production occurrence. Figure resembles other TGFs measured from RHESSI and BATSE. TGF is believed to have been far away thereby explaining the low count rate. On Aug. 21, the GV aircraft mistakenly entered an anvil thundercloud. Possible positron bursts and a bright surge also occurred from this day as did a TGF. Only one TGF was measured on this campaign Leads us to believe that TGFs are rare and that they probably are not the sole trigger mechanism of lightning.
Mobile Lightning Detector System - MLDS GPL Lightning Group - Physics Dept. 29 ADELE into the SUV Around Central Florida XLB and ADELE x-ray measurements Radiosonde measurements FastCam High Speed Camera
Mobile Lightning Detector System - MLDS GPL Lightning Group - Physics Dept. 30 1.ADELE monitor and camera 2.Yoko and Lecroy scopes for XLB 3.Graduate students discussing problems 4.XLB 5.Flat plate antenna 1. 5.4. 3.2.
X-ray burst from natural lightning strike on the ground campaign GPL Lightning Group - Physics Dept. 31 Analyze sodium iodide and plastic data with our search algorithm to find TGF-like events that contain unique characteristics for both ground and flight data. Start preparing for future ADELE missions. ADELE – Work to be done