Understanding Lightning: Thunder
Many of us have heard that if you determine the lightning distance from you to a strike by counting the number of seconds between hearing thunder and seeing a lightning strike, that is how far away in miles the lightning is (not true). Jun 26, · Here's a simple method for calculating your distance from a lightning strike. Just count the number of seconds that pass between a flash of lightning and the crack of thunder .
Yo flash of lightning brightens the sky and is followed seven seconds later by the ominous roar of thunder. How far away was the lightning strike? Cloud-to-ground lightning discharge in what drugs are made from opium field from a cumulonimbus cloud.
Sound waves propagate through different materials at different speeds. Counting the seconds between the strike and the arrival of the thunder and dividing the number of seconds by ligytning gives us a disgance estimate strikw the distance to the strike in miles dividing by three for a distance in kilometers. So, in the example above, the strike would have been about 1.
Top As shown in the chart, the elapsed time between seeing a flash of lightning and hearing the thunder is roughly three seconds for each kilometre, or five seconds for each mile. Feedback: customer service. Comments closed. Britannica Blog Categories. The Obama Presidency Web 2. Britannica Blog Archive by Year.
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Weather Warnings - Safety - Meteorology
Counting the seconds between the strike and the arrival of the thunder and dividing the number of seconds by five gives us a rough estimate of the distance to the strike in miles (dividing by three for a distance in kilometers). So, in the example above, the strike . Dec 13, · How to Determine Distance between Thunder and Lightning Thunder can be heard from a distance of approximately 10 miles from the point of the lightning strike. If you can hear the sound of thunder, it’s a warning that you’re within striking distance of the storm. Lightning Distance Equation Formulas Calculator Weather Warnings - Safety - Meteorology. Solving for distance to lightning. Note, the speed of sound (s) is approximately to feet per second. Inputs: Solve for the lightning strike distance. Solve for the speed of sound.
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.
The first such device was invented in by Alexander Stepanovich Popov. It also was the first radio receiver in the world. Ground-based and mobile detectors calculate the direction and severity of lightning from the current location using radio direction-finding techniques along with an analysis of the characteristic frequencies emitted by lightning.
Ground-based systems use triangulation from multiple locations to determine distance, while mobile systems estimate distance using signal frequency and attenuation. Space-based detectors on satellites can be used to locate lightning range, bearing and intensity by direct observation.
Each system used for lightning detection has its own limitations. Lightning detectors and weather radar work together 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. The first image on the right shows the life cycle of a thunderstorm :. 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 farther away. Lightning detectors do not suffer from a masking effect and can provide confirmation when a shower cloud has evolved into a thunderstorm. 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. 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 radio atmospherics : Stormscope , produced originally by Ryan later B.
Goodrich and currently by L-3 Communications, and the Strikefinder , produced by Insight. Strikefinder can detect and properly display IC intracloud and CG cloud to ground strikes as well as being able to differentiate between real strikes and signal bounces reflected off the Ionosphere. Lightning 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.
Inexpensive portable lightning detectors as well as other single sensor lightning mappers , such as used on aircraft, have limitations including detection of false signals and poor sensitivity , particularly for intracloud IC lightning. Professional-quality portable lightning detectors improve performance in these areas by several techniques which facilitate each other, thus magnifying their effects:. When a lightning discharge occurs within a cloud at night, the entire cloud appears to illuminate.
In daylight these intracloud flashes are rarely visible to the human eye; nevertheless, optical sensors can detect them. Looking through the window of the space shuttle in early missions, astronauts used optical sensors to detect lightning in bright sunlit clouds far below.
When an RF lightning signal is detected at a single location, one can determine its direction using a crossed-loop magnetic direction finder but it is difficult to determine its distance. Attempts have been made using the amplitude of the signal but this does not work very well because lightning signals greatly vary in their intensity.
Thus, using amplitude for distance estimation, a strong flash may appear to be nearby and a weaker signal from the same flash — or from a weaker flash from the same storm cell — appears to be farther away. One can tell where lightning will strike within a mile radius by measuring ionization in the air to improve the accuracy of the prediction. To understand this aspect of lightning detection one needs to know that a lightning 'flash' generally consists of several strokes, a typical number of strokes from a CG flash is in the range 3 to 6 but some flashes can have more than 10 strokes.
The strokes in a CG flash can be seen at night as a non-periodic sequence of illuminations of the lightning channel. This can also be heard on sophisticated lightning detectors as individual staccato sounds for each stroke, forming a distinctive pattern. Single sensor lightning detectors have been used on aircraft and while the lightning direction can be determined from a crossed loop sensor, the distance can not be determined reliably because the signal amplitude varies between the individual strokes described above,  : and these systems use amplitude to estimate distance.
Because the strokes have different amplitudes, these detectors provide a line of dots on the display like spokes on a wheel extending out radially from the hub in the general direction of the lightning source.
The dots are at different distances along the line because the strokes have different intensities. But unless the sensor is close to the flash they do not pick up the weaker signals from IC discharges which have a significant amount of energy in the high frequency HF range up to 30 MHz. Another issue with VLF lightning receivers is that they pick up reflections from the ionosphere so sometimes can not tell the difference in distance between lightning km away and several hundred km away.
Electromagnetic pulses transmitted by lightning strikes propagate within that waveguide. The waveguide is dispersive, which means that their group velocity depends on frequency. The difference of the group time delay of a lighting pulse at adjacent frequencies is proportional to the distance between transmitter and receiver. Together with the direction finding method, this allows locating lightning strikes by a single station up to distances of km from their origin.
Moreover, the eigenfrequencies of the Earth-ionospheric waveguide, the Schumann resonances at about 7. Several such national networks currently operating in the U. These are called lightning mapper arrays. They typically cover a circle 30—40 miles in diameter. From Wikipedia, the free encyclopedia.
National Lightning Safety Institute. Retrieved Kitagawa Journal of Geophysical Research. Bibcode : JGR David The Electrical Nature of Storms. Oxford University Press, NY. ISBN In Volland, Hans ed. Handbook of Atmospheric Electrodynamics, Vol. Bibcode : JGRD.. Journal of Meteorology. Bibcode : JAtS Weyer Bibcode : Sci PMID Williams and T. Kennan Bulletin of the American Meteorological Society. Bibcode : BAMS The Lightning Discharge. Academic Press, N.
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