LIGHTNING

Atmospheric Phenomenon

WHAT IS LIGHTNING?

Lightning is the electrical discharge between positively and negatively charged regions within clouds. The electrical discharge serves as an equalization process between the charged regions, and can travel from cloud-to-cloud, cloud-to-ground, or cloud-to-air. Visually, lightning is comprised of bright flashes of light called strokes. The loud sound of thunder that accompanies lightning is a sonic shock wave produced by the rapid expansion of the air surrounding the lightning channel during the stroke, similar to a sonic boom. Lightning and thunder occur at the same time, however, because light travels faster than the speed of sound, lightning may be observed sooner than thunder is heard.

Image Source: Wikimedia Commons


 

Image Source: NOAA NSSL


 

Why does lightning occur?

Growing ice particles within a cloud interact with each other through collision, causing the particles to fracture and break apart.  It is currently believed that smaller ice particles tend to acquire a positive charge, while the larger particles acquire a more negative charge.  Under the influences of thunderstorm updrafts and gravity, these particles separate until the upper portion of the cloud acquires a net positive charge, and the lower portion of the cloud becomes negatively charged. This separation of charge produces electrical potential both within the cloud and between the cloud and ground.  Eventually, the electrical resistance in the air between the charged regions breaks down and a flash begins. The resulting lightning strokes are an electrical discharge between the positive and negative regions of a thunderstorm.

Where does lightning occur?

Lightning occurs in many places around the world. Over the land, much more lightning is observed than over ocean regions. In addition, not all land regions experience the same amount of lightning. Spatial differences in lightning distribution may result from the variable topography and weather patterns of different regions. The place on Earth with the most lightning strikes per square kilometer is Lake Maracaibo, a large tidal bay in northern Venezuela.  Here lightning occurs 300 nights a year.

ASSOCIATED PHENOMENON

Severe Storms

Snow Storms

Hurricanes

Volcanic Eruptions

Wildfires

HOW IS LIGHTNING OBSERVED?

Lightning can be detected by a variety of ground-based, mobile and space-based instrument systems such as those flown aboard research aircraft, lightning arrays, and optical sensors on satellites. By measuring and monitoring changes in Earth’s electric field, lightning can be detected using instruments such as electric field mills, interferometers and radio frequency antennas.  Arranging these instruments in lightning arrays allows scientists to locate, map and study the spatial and temporal structure of lightning through triangulation.  In addition, lightning can be detected optically using instruments such as the lightning imaging sensor (LIS) and high speed cameras that monitor changes in light, or the electromagnetic spectrum, to detect lightning flashes from space and Earth’s surface.  The table below provides an overview of the instruments used to obtain GHRC lightning data.
 
GHRC Lightning Instruments
 
INSTRUMENT PLATFORM PLATFORM TYPE APPLICATION
Lightning Imaging Sensor (LIS) ISS
TRMM

Spaceborne

Lightning climatology
Mesoscale phenomena
Convective precipitation
Optical Transient Detector (OTD) OrbView-1 (formerly MicroLab-1)

Spaceborne

Optical lightning detection
Lightning discharge detection
Radiant energy measurements
Radio Frequency (RF) Antenna
 
NLDN
LDAR
WWLLN
LMA
NAMMA

Ground based

Lightning flash detection
Lightning polarity
Signal strength
Lightning mapping
Lightning Instrument Package (LIP)
DC-8
ER-2
Global Hawk UAV

Airborne

Tropical cyclone development
Electric field measurements
Electrical structure of storms
Total lightning
Electric charge
Air conductivity
Electric Field Mill Ground station

Ground based

Lightning development/ dissipation
Lightning warnings
Electric field strength
Electric charge
Operational Line Scanner (OLS)
DMSP-5B-F3
DMSP-F1
DMSP-F7
DMSP-F8
DMSP-F10
DMSP-F12

Spaceborne

Nighttime lightning detection
Lightning discharge

 

RESEARCH AND APPLICATION AREAS

Relevant Publications
Climatology
Cecil, D. J., Buechler, D. E., & Blakeslee, R. J. (2014). Gridded lightning climatology from TRMM-LIS and OTD: Dataset description. Atmospheric Research, 135, 404-414, doi:10.1016/j.atmosres.2012.06.028.
 
Williams, E. R. (2005). Lightning and climate: A review. Atmospheric Research, 76(1), 272-287, doi:10.1016/j.atmosres.2004.11.014.
 
Science Application Areas
Schultz, C. J., Petersen, W. A., & Carey, L. D. (2011). Lightning and severe weather: A comparison between total and cloud-to-ground lightning trends. Weather and forecasting, 26(5), 744-755, doi:10.1175/WAF-D-10-05026.1
 
Curran, E. B., Holle, R. L., & López, R. E. (2000). Lightning casualties and damages in the United States from 1959 to 1994. Journal of Climate, 13(19), 3448-3464, doi:10.1175/1520-0442(2000)013<3448:LCADIT>2.0.CO;2 .
 
McCaul Jr, E. W., Goodman, S. J., LaCasse, K. M., & Cecil, D. J. (2009). Forecasting lightning threat using cloud-resolving model simulations. Weather and Forecasting, 24(3), 709-729, doi:10.1175/2008WAF2222152.1.
 
Physical Processes
Fierro, A. O., Mansell, E. R., MacGorman, D. R., & Ziegler, C. L. (2013). The implementation of an explicit charging and discharge lightning scheme within the WRF-ARW model: Benchmark simulations of a continental squall line, a tropical cyclone, and a winter storm. Monthly Weather Review, 141(7), 2390-2415, doi:10.1175/MWR-D-12-00278.1.
 
MacGorman, D.R. and Rust, W. D. (1998).  The electrical nature of storms.  Oxford University Press.  432 pp.
 
Williams, E. R. (2009). The global electrical circuit: A review. Atmospheric Research, 91(2), 140-152, doi:10.1016/j.atmosres.2008.05.018.
 
Rakov, V. A., & Uman, M. A. (2003). Lightning: physics and effects. Cambridge University Press.  700 pp.
 
Rakov, V. A., & Uman, M. A. (1998). Review and evaluation of lightning return stroke models including some aspects of their application.Electromagnetic Compatibility, IEEE Transactions on, 40(4), 403-426, doi:10.1109/15.736202.
 
DATE UPDATED
Sep 20th, 2017
AUTHOR(S)
Kaylin Bugbee
Patrick Gatlin
Leigh Sinclair
Deborah Smith
Amanda Weigel
MICRO ARTICLE TYPE
Phenemonon

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