The Science of Thunder - National Lightning Safety Institute
How does this happen if thunder and lightning come from the same place and bolt in the distance, count how many seconds it takes to hear the thunder. where the relationship between light and sound are distinguishable. between lightning and thunder determines a storm's distance from your roughly five seconds for the sound of super heated air or thunder to. The formula is to divide the number of seconds by the speed of sound in feet per second. The delay between when you see lightning and when you hear thunder .
All thunderstorms go through stages of growth, maturity, and dissipation. The life span of a thunderstorm can be as short as 45 minutes or as long as 12 hours. Lightning is initiated by the attraction of positive and negative charges, but air gases in our atmosphere acts as an insulator to inhibit the flow of electricity between electrical polarities.
When the electrical potential builds up to overcome resistance of the air, lightning will occur. Some intense thunderstorms over land have been known to tower over 70, feet 21, m.
- Early Theories
- Light and Sound Speed
There are flashes to ground occurring every second on earth. The lightning capital in the U. The vertical extent of a CG lightning channel averages miles Most CG flashes originate in thunderstorms between 15, feet 4, m above ground level in the mixed water and ice region.
The record horizontal distance of a cloud flash is miles km that occurred in the Dallas-Ft. Most lightning in the continental U. The Pacific Coast states in the U. Lightning is typically associated with the warm season, but has occurred in winter during heavy snowfalls.
A man was struck by lightning during a blizzard in Minneapolis, Minnesota in March and another man in Vail, Colorado in April In Februarya year-old boy was struck by lightning while sledding. Two men, one from Maine and the other from Chicago, were struck by lightning during a snowstorm in the winter of During a cloud-to-ground flash, the first stroke of lightning is downward from the cloud along the channel.
A flash consists of one or more return strokes. A CG flash may have only one return stroke, but usually has more two to three. They are called returned strokes because the flash originates in the cloud, not at the ground. The flash and strokes lower charge to ground. Then objects on the ground send up streamers to meet the leader coming down. It is routinely followed by two to three downward return strokes to ground.
This is why you see lightning flicker during a CG flash. A record number of return strokes occurred at Cape Canaveral, Florida when 26 return flashes were recorded. Research has revealed that during a CG lightning flash, the initial stroke does not produce as loud or as long a thunder as subsequent return strokes. Thunder Definitions The sounds produced by thunder have been categorized into recognizable terms.
Claps are sudden loud sounds lasting 0. Peals are sounds changing frequency or amplitude. Rolls are irregular sound variances. Rumbles are of long duration but relatively low in frequency. Malan described these in more technical terms: A typical thunder episode consists of a rumble and a roll, on which three to four peals or claps are superimposed.
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The step leader comes from the cloud toward the ground. Then the return stroke is later.4 hours of rain and thunder, real storm sound for good sleep -Thunderstorm #1
Of course, on the ground, we hear the closet part first, which are the upward streamers, then the step leader, which is farther away but occurred first. People who fear the sound of thunder suffer from a phobia called brontophobia and the fear of lightning is called keraunophobia.
Ninety percent of the electrical energy of lightning is released in the form of heat, which is quickly dissipated into the atmosphere. A sudden increase in pressure and temperature causes surrounding air to expand violently at a rate faster than the speed of sound, similar to a sonic boom. The shock wave extends outward for the first 30 feet 10 mafter which it becomes an ordinary sound wave called thunder. Thunder is exploding air occurring along the entire length of the lightning channel.
Sound velocity is proportional to the square root of temperature. Temperature typically decreases with height, unless there is an inversion warm air over cooler air.
Thus, the sound of thunder will be deflected upward. Humidity, wind velocity, wind shear, temperature inversions, terrain features, and clouds, also influence thunder's audibility. The loudness of thunder can be expressed in decibels dB.
A clap of thunder typically registers at about dB in close proximity to the ground stroke. This is 10 times louder than a garbage truck or pneumatic jackhammer drill. Thunder in close proximity is capable of producing temporary deafness and may cause rupturing of the ear's tympanic membrane that can lead to hearing damage or deafness.
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At very close range, thunder is capable of causing property damage. The shock wave, pressure, and propagation of thunder may cause exterior and interior damage to structures. Popping of nail-supported drywall away from horizontal and vertical wooden studs inside houses has been documented. Glass windows have been broken by the concussion of thunder. Thunder contains a somewhat cylindrical initial pressure shock wave along the lightning channel in excess of 10 times the normal atmospheric pressure.
This shock wave decays rapidly into a sound wave within feet or meters. When thunder is heard from about feet m distance, it consists of one large bang, yet hissing and clicking may be heard just prior to the bang upward streamers. Thunder is seldom heard beyond 10 miles 16 km under ideal conditions. The sound of distant thunder has a characteristic low-pitched rumbling sound.
Pitch, the degree of highness or lowness of a sound, is due to strong absorption and scattering of high-frequency components of the original sound waves, while the rumbling results from the fact that sound waves are emitted from different locations along the lightning channel, which lie at varying distances from a person. The longer the lightning channels, the longer the sound of thunder.
Humans hear frequencies of thunder between Hertz Hz. Special listening devices are required to record these inaudible sounds.
Thunder vs. Lightning
Thunder and Lightning Facts Lightning is the number two thunderstorm-related killer in the U. On average, it kills more people each year than do tornadoes and hurricanes. A hundred years ago, lightning probably was the leading thunderstorm-related killer.
At that time, the U. The majority of people worked outside, exposing them frequently to the threat of lightning compared to today. In addition, housing was much less substantial, lacking the plumbing and wiring that we have today that acts more or less like a Faraday cage to channel lightning around and away from the inhabitants. It was not unusual for a structure to literally blow apart when hit by lightning, often crushing the inhabitants. Lightning and its subsequent thunder can be used in lightning safety to protect yourself and others.
The flash-to-bang method of protection considers the time between seeing lightning to hearing its thunder. New lightning data showed that most CG flashes in a storm were within miles Using the flash-to-bang method, lightning that has a second count between the flash and the thunder is 6 miles 9. This translates into 5 seconds per mile 1. It is possible that the next flash of CG lightning may occur at your location. The LSG also suggests waiting 30 minutes after hearing the last sound of thunder or seeing the last lightning in daytime before returning to any outside activity.
This allows the thunderstorm to move out of the area, greatly reducing the lightning threat level. The average lightning flash distance between two flashes averages about mikes kmbut 6 miles 9. The LSG strongly recommends proactive action rather than a reactive approach to lightning safety. This means knowing the weather prediction and pre-planning for a scene evacuation that includes knowing a safer place to go and the time needed to reach it.
Statistics have shown the majority of people who are struck by lightning are struck before or after a thunderstorm, not during the heaviest rain. A few short rhymes or slogans to remember for lightning safety are as follows: The answer involves the speed at which sound and light travel. Light is the electromagnetic radiation within a certain portion of the electromagnetic spectrum.
Lightning causes light in the form of plasma, which is created by the electrostatic discharge that take place between the electrically charged regions of two or more clouds, or the electrically charged regions of a cloud and the ground. The term "light" mostly refers to visible light, which is responsible for the sense of sight in the human eye.
Wavelengths around nano-meters make up visible light. Light travels atmeters per second , mphso in theory, nothing moves faster than the speed of light. This is significantly slower than the speed of light. This indicates that the reason why you would see lightning first in a thunderstorm is because the visible light waves formed by the plasma in the lightning travels to your eyes much faster than the rumble or crack of thunder reaches your ears.
Therefore, when you hear rumbling thunder, the lightning bolt was far away because of the effect of dispersion, which is the action or process of distributing things over a wide area.
When you hear a very loud crack or boom, this means that the lightning bolt was near your location. Fireworks from the Lake of Annecy Festival in France. Wikimedia Commons Using this relationship between seeing lightning and hearing thunder, you can determine a rough estimate of how far a thunderstorm is from your current location.
After seeing a lightning bolt in the distance, count how many seconds it takes to hear the thunder. The number of seconds it took to hear the thunder is approximately how many miles away the lightning bolt was from your position.