FACTOID # 12: It's not the government they hate: Washington DC has the highest number of hate crimes per capita in the US.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Lightning detector
Lightning detector at the Kennedy Space Center in Florida.
Enlarge
Lightning detector at the Kennedy Space Center in Florida.

A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location (often aboard an aircraft), and space-based systems. A shelf cloud associated with a heavy or severe thunderstorm over Enschede, The Netherlands. ...


Ground-based and mobile detectors calculate the direction and severity of lightning from the current location using radio direction-finding techniques together with an analysis of the characteristic frequencies emitted by lighting. Ground-based systems use triangulation from multiple locations to determine distance, while mobile systems estimate distance using signal frequency and attenuation. Space-based lighting detectors, on artificial satellites, can locate range, bearing and intensities by direct observation. Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... Triangulation can be used to find the distance from the shore to the ship. ... Reduction of signal strength during transmission. ... For other uses, please see Satellite (disambiguation) A satellite is an object that orbits another object (known as its primary). ...


Ground-based lightning detector networks are used by meteorological services like the National Weather Service in United States and the Meteorological Service of Canada, and by other organizations like electrical utilities and forest fire prevention services. The National Weather Service (NWS) is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. ... The Meteorological Service of Canada (MSC) is a Canadian government agency which provides meteorological information. ...

Contents

Limitations

Each system used for lightning detection has its own limitations[1]. These include:

  • A ground-based lightning network must be able to detect a strike with at least three antennas to locate it with an acceptable margin of error. This often leads to the rejection of cloud-to-cloud lightning, as one antenna might detect the position of the strike on the starting cloud and the other antenna the receiving one. As a result, ground-based networks have a tendency to underestimate the number of strikes, especially at the beginning of storms where cloud-to-cloud lightning is prevalent.
  • Since they use attenuation rather than triangulation, mobile detectors sometimes mistakenly indicate a weak lightning strike nearby as a strong one further away, or vice-versa.
  • Space-based lightning networks suffer from neither of these limitations, but the information provided by them is often several minutes old by the time it is widely available, making it of limited use for real-time applications such as air navigation.

Lightning detectors vs. weather radar

A thunderstorm life cycle and associated reflectivities from a weather radar
Enlarge
A thunderstorm life cycle and associated reflectivities from a weather radar
Distribution of electric charges and lightning strikes in and around a thunderstorm
Enlarge
Distribution of electric charges and lightning strikes in and around a thunderstorm

Lightning detectors and weather radar are complementary to detect storms. Lightning detectors indicate electrical activity, while weather radar indicates precipitation. Both phenomena are associated with thunderstorms and can help indicate storm strength. In optics, reflectivity is the reflectance (the ratio of reflected power to incident power, generally expressed in decibels or percentage) at the surface of a material so thick that the reflectance does not change with increasing thickness; , the intrinsic reflectance of the surface, irrespective of other parameters such as the... To meet Wikipedias quality standards, this article or section may require cleanup. ...


The first image on the right shows the life cycle of a thunderstorm:

  • Air is moving upward due to instability.
  • Condensation occurs and radar detects echoes above the ground (colored areas).
  • Eventually the mass of rain drops is too large to be sustained by the updraft and they fall toward the ground.

The cloud must develop to a certain vertical extent before lightning is produced, so generally weather radar will indicate a developing storm before a lightning detector does. It is not always clear from early returns if a shower cloud will develop into a thunderstorm, and weather radar also sometimes suffers from a masking effect by attenuation, where precipitation close to the radar can hide (perhaps more intense) precipitation further away. Lightning detectors do not suffer from a masking effect and can provide confirmation when a shower cloud has evolved into a thunderstorm. To meet Wikipedias quality standards, this article or section may require cleanup. ...


Lightning may be also located outside the precipitation recorded by radar. The second image shows that this happens when strikes originate in the anvil of the thundercloud (top part blown ahead of the cumulonimbus cloud by upper winds) or on the outside edge of the rain shaft. In both cases, there is still an area of radar echoes somewhere nearby. Cumulonimbus (Cb) is a type of cloud that is tall, dense, and involved in thunderstorms and other bad weather. ...


Aviation use

Large airliners are more likely to use weather radar than lightning detectors, since weather radar can detect smaller storms that also cause turbulence; however, modern avionics systems often include lightning detection as well, for additional safety.


For smaller aircraft, especially in general aviation, there are two main brands of lightning detectors (often referred to as sferics, short for atmospherics): Stormscope, produced originally by Ryan (later B.F. Goodrich) and currently by L-3 Communications, and the Strikefinder, produced by Insight. Lighting detectors are inexpensive and lightweight, making them attractive to owners of light aircraft (particularly of single-engine aircraft, where the aircraft nose is not available for installation of a radome). General aviation (abbr. ... Radomes at the Misawa Security Operations Center, Misawa, Japan. ...


References

  1. ^ An Overview of Lightning Detection Equipment. National Lightning Safety Institute (2006). Retrieved on 2006-07-07.

2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... July 7 is the 188th day of the year (189th in leap years) in the Gregorian Calendar, with 177 days remaining. ...

External links

  • Recent North American lightning activity from Environment Canada
  • Lightning detection guide (PDF) from the U.S. NOAA
  • Lightning origin and research on detection from space from NASA
  • Blog posting about lightning detection and air traffic control
  • Archived e-mail thread comparing the Stormscope and Strikefinder
  • Stormscope product page
  • Strikefinder product page

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m