Sparky the electron is looking for an atom family to join but in the mean time he is educating a family on lightning.
This show covers several of our 4th through 6th grade Weather unit standards.
- Water Cycle
- Watch vs. Warning
It also covers the scouts Weather badge starter and belt loops.
From the producers:
About Enlightening Lightning
Funded by the National Science Foundation, we have developed a show for the planetarium at Tarleton State University in Stephenville, TX. The 40 minute production is on lightning and focuses on both the science behind thunderstorms as well has how to stay safe and avoid danger. Our primary audience is 6‐8th graders.
The show begins with a family preparing to go on a hike at the local State Park. The family has a mom, dad, and two children ‐ a boy in 6th grade and a girl in 9th grade. As they are eating breakfast, the morning weather report comes on predicting storms for the afternoon. The family decided to go on the hike despite the weather prediction.
The family is followed throughout their day as they hike, eat lunch, talk with a lifeguard, seek shelter when a storm develops, and return home to review their day. Throughout the story line, an animated character, Sparky, keeps appearing to discuss various scientific points. Sparky is an electron who is looking for his perfect molecule family. Sparky presents the science facts in a fun, easy to understand way. More science facts and narration are covered by Rebecca Miller of NBC station KXAS in Dallas‐Fort Worth TX. Ms. Miller discusses more of the details behind cloud development and safety issues. She also appears on the family's TV in both the morning and evening to discuss the weather.
This is a joint effort between the planetarium at Tarleton State University and the Visualization Lab at Texas A&M in College Station, TX. Supporting our efforts is the National Storms Laboratory in Norman, Oklahoma as well as the Department of Atmospheric Sciences at Texas A&M and KXAS.
Taken from Understanding Lightning by Martin Uman
- Why did Ben Franklin fly the kite?
- Ben Franklin sought to prove that lightning was electrical. His goal was to show that the clouds are electrically charged, for if so, then lightning was as well.
- During a thunderstorm in 1752, sparks jumped from a key tied to the bottom of the kite string to the knuckles of his hand, thus verifying his theory.
- How does a lightning rod work?
- Lightning rods do not discharge clouds and thus prevent lightning. Rather they only serve to route lightning harmlessly to the ground. This way they divert lightning when it is 10 to 100 yards away.
- “The charge flowing between a lightning rod and a thundercloud is much too small to discharge the thundercloud. The rod diverts to itself a stroke on its way to the earth but can do so only in the final part of the stroke’s earthward trajectory. Diversion is achieved by the initiation of an electrical discharge, a sort of traveling spark, which propagates from the rod, intercepts the downward‐moving lightning, and provides a conducting path to the rod. Before the traveling spark is initiated, the downward‐moving lightning is essentially uninfluenced by objects on the ground beneath it. The traveling spark is generally 10 to 100 yards long when it meets the lightning.
- Any high object may initiate an upward=moving spark which attempts to reach the downward‐moving lighting. It is therefore important that the lightning rod be the tallest object near the structure it protects, so that its traveling spark catches the lightning rather than a spark initiated by the chimney or a nearby tree.” (Uman pg 9)
- How many people are killed each year by lightning?
- There are no exact figures because there is no central agency to which lightning accidents are reported. However various studies have reported the average number of deaths in the US to be 100, 137, 151, 300, and even 600. Lightning is the cause of more direct deaths than any other weather occurrences. About 2/3 rds of those involved in lightning related accidents make a complete recovery.
- “The largest single category of lightning deaths is composed of those unfortunate individuals who seek refuge under trees during thunderstorms and have their sheltering trees struck by lightning.” (Uman pg 18) Golfers especially need to be aware of the dangers of lightning.
- What should I do if caught outdoors in a thunderstorm?
- What NOT to do if caught in a thunderstorm – do not make a lightning rod of yourself and do not stand beneath a lightning rod. Try not to project above the surrounding landscape. Do not stand under isolated trees or any other isolated shelters. Avoid wire fences, overground pipes, rails, and other metallic paths along the ground which could carry lightning that has hit farther away to you. Avoid swimming since lightning can travel through water.
- What TO do – in an urban area, seek shelter in a building – preferably one with a metal frame or lightning rod or in a car with the windows rolled up. In wide open spaces seek a ravine, valley, or a depression in the ground. Crouch or lie down. In the woods, seek an area dense with trees.
- Is it safe to talk on a telephone during a thunderstorm? Shower?
- Do not talk on a corded telephone during a storm (cordless is ok, cell phones are ok). Indoors try to avoid fixtures connected to the house plumbing or to appliances that are plugged into the house wiring system. So yes, avoid the shower as well.
- Should I unplug radios and TVs?
- How can I help someone struck by lightning?
- “Lightning “deaths” are often reversible. Many victims who appear dead, in that they are not breathing and have no heartbeat, can be revived with proper first aid. It is tragic that this fact is not more widely known. If a victim is still breathing he will, in all probability, recover.” (Uman 22)
- “If the victim’s heart has started spontaneously but his breathing has not, mouth‐to‐mouth artificial respiration should be given at about 10 to 20 breaths per minute. If the heart is not beating (if the victim has no pulse), both heart action and breathing must be re‐started. Heart action can be stimulated by placing the victim on his back and pressing firmly on his chest with the heel of the hand once every second or slightly faster. A person alone with the victim should alternate between about five cycles of chest pressure and the same number of mouth‐to‐mouth artificial respiration cycles. If two rescuers are present, one should apply mouth‐to‐mouth respiration, the other chest pressure. This first aid should be continued until the victim’s heart action and breathing begin or until professional medical help is secured.” (Uman 23)
- Am I safe from lightning in an airplane? In a car?
- “To be safe from lightning really means being certain that none of the lightning current can flow through you.” (Uman 25)
- “Lightning which travels many miles through insulating air is not about to be halted by half an inch or even a yard of insulation rubber. The rubber tires on a car do not serve to insulate the car from ground and thereby prevent it from being struck by lightning as is commonly believed. A car is a relatively safe shelter in a thunderstorm, because, if it is struck by lightning, the current will tend to flow in the metal skin of the car and not in the occupant. The lighting will ground itself by jumping from the car to the earth either through the air, along the surface of a tire, or through a tire. (in which case the tire will be destroyed). For maximum security, the car windows should be rolled up and wet and the occupant should not touch any metal part of the car or the car radio.” (Uman pg 25, 26)
- Because airplanes are almost entirely metal, lightning rarely enters them. Airplanes on the ground are relatively safe during a thunderstorm. Airplanes in flight do get struck by lightning. Almost always they continue to fly (unless the gas tank is hit).
- How does lightning damage trees and buildings?
- Lightning can strike a tree and leave no visual damage or it can cause considerable damage. Most trees struck by lightning are not killed. However they are often weakened and more susceptible to insects and diseases.
- A complete lightning discharge is called a flash. A lightning flash lasts a few tenths of a second. Each flash between cloud and ground is composed of a number of component strokes, ranging from one to 20 or 30 but usually about three or four. Lightning with multiple component strokes appears to flicker.
- The bottom end of the lightning channel can be thought of as a source of current which is forced into the lightning attachment point. This current generates heat in the object through which it flows. The amount of heat depends on the object’s resistance to electrical current. If the object has a low resistance – i.e. is a conductor, like metal – then there is relatively little heating. If the object has a high resistance (like wood or plastic) then there is a great deal of heating although not necessarily enough to cause burning. The essentially instantaneous lightning current rise inside a high‐resistance material causes rapid heating and consequent vaporization (conversion from solid to gas) of some of the internal material. As a result, a very high pressure is quickly generated within the material and, typically, this pressure blows the material apart. (Uman pg 44, 45)
- Does lightning “never strike twice”?
- Much of what is known about lightning today has been discovered precisely because lightning does strike the same structure over and over again. The empire state building in New York City is struck by lightning an average of about 23 times per year. As many as 48 strikes have been recorded in one year, and during one thunderstorm eight strikes occurred within 24 minutes.
- The probability of a structure being struck by lightning depends on its height. However any structure, regardless of its height may be struck by lightning.
- Does lightning always strike the tallest object?
- The Empire State Building has been struck 50 ft below the top. It is thought that the greater the electrical charge residing on the downward moving stepped leader, the longer will be the connecting leader propagating upward from the building top. Thus, a relatively weak stepped leader can come closer to a building top without drawing an upward leader than can a relatively strong stepped leader. It is possible; therefore, that a weak stepped leader might “sneak” past the top of a building and only draw a leader when it has reached some lower level.
- Another explanation – the obvious strike point has been kept from generating an upward‐moving leader by a pocket of airborne charge (so called space charge). Properly distributed regions of space charge could cause the lightning to strike almost anywhere. (Uman pg 53)
- How are thunderstorms formed?
- The conditions necessary for the formation of a local thunderstorm are: 1. the air from ground level to many thousands of feet must be moist, 2. the atmosphere must be “unstable”, and 3. the sun must heat the ground and the air near the ground. In an unstable atmosphere, hot, wet air near the ground will rise to heights where the temperature is below freezing, eventually forming an thundercloud. (Uman pg 59)
- There are three stages in the life of a local or convective thundercloud: cumulus, mature, and dissipating. The cumulus stage begins when small, fluffy white, cumulus clouds combine to form a larger cloud, a cumulus congestus, perhaps a mile in diameter, with a well‐defined top which rises at 1000 to 2000 ft per minute. The primary characteristic of the cumulus stage is that air motion throughout the cloud is upward. The cumulus stage lasts 10 to 15 minutes. As the cumulus congestus cloud grows, water drops and ice form within the cloud. Eventually the rain, hail, and snow within the cloud become sufficiently heavy that they can no longer be moved upward by the prevailing updrafts.
- The formation of heavy precipitation signals the beginning of the mature stage. Precipitation begins to fall, dragging air downwards with it. The cloud, now a cumulonimbus, contains both updrafts and downdrafts, and rain from the cloud reaches the ground. The top of a mature thundercloud may extend to 60,000 ft. It flattens out and assumes a characteristic anvil shape on reaching the stratosphere, the region of the atmosphere in which temperature is constant or increases with height. The mature stage of the storm lasts 15 to 30 minutes and is accompanied by considerable lightning activity. Finally the storm enters it dissipating stage. The violent updrafts and downdrafts decrease, and precipitation is less intense. The water droplets in the cloud evaporate, and the remainder of the cloud is blown away. The dissipating stage lasts about 30 minutes. The total lifetime of the convective thundercloud is roughly an hour. (Uman pg 61)
- Are their locations with no lightning?
- Some parts of the world have a great deal of lightning while others have essentially no lightning. The degree of thunderstorm activity in a particular geographical area depends on its prevailing meteorological conditions. (Uman pg 59)
- How many thunderstorms are in progress in the world at one time?
- About 2000.
- Does cloud lightning differ from cloudtoground lightning? Which is more common?
- There are two principal types of lightning discharges – flashes which occur between the thundercloud and the earth (cloud‐to‐ground discharges) and flashes within the thundercloud (intracloud discharges). Other types of discharges such as cloud‐to‐cloud lightning and cloud‐to‐air lightning also occur but not very frequently. It is a widespread misconception that cloud‐to‐cloud lightning is common. (Uman pg 65)
- Does lightning occur only in thunderstorms?
- Although the thundercloud is the most common source of lightning, it is not the only one. Lightning occurs in snowstorms, in sandstorms, in non‐thunderstorm rain and ice, in the ejected material above erupting volcanoes, near the fireballs created by nuclear explosions, and apparently even out of the clear blue sky. (Uman pg 65)
- Does a stroke between cloud and ground travel upwards or downwards?
- It does both. The usual lightning flash between cloud and ground (excluding the discharges initiated by tall structures) begins with a visually undetected downward‐moving traveling spark called the stepped leader. Since the lightning flash begins with a downward‐moving discharge, lightning moves from the cloud to the ground. On the other hand, when the stepped leader reaches ground (or is contacted by and upward‐moving discharge some tens of yards above the ground) the leader channel first becomes highly luminous at the ground and then at higher and higher altitudes. The bright, visible channel, or so=called return stroke, is formed from the ground up, and one could say, therefore, that visible lightning moves from the ground to the cloud. (Uman pg 73)
- How long and how wide is the lightning channel?
- How long – varies from over 90 miles to a few yards. The average vertical stroke height is about 3 to 4 miles. The lightning channel diameter is about an inch.
- Why is lightning zigzag?
- We don’t really know. The larger‐scale zigzags are due to the fact that the stepped leader makes such an errant trip to ground. Possibly due to various airborne regions of charge which divert the leader on its trip. Or the leader jus doesn’t know exactly where it wants to, except that ultimately it wants to move downward. The smaller scale zigzags are formed possibly by the magnetic forces associated with the return stroke current. (Uman pg 90)
- How can I best photograph lightning?
- Put your camera on a tripod pointed in the direction of the storm, leaving the shutter on until lightning occurs in the field of view. This only works at nighttime. Camera focus should be set at infinity.
- How hot is lightning?
- Five times hotter than the surface of the sun.
- How is thunder generated?
- The return stroke rapidly deposits a large amount of energy along the leader channel. That channel is heated by the energy input to above 50,000 Degrees K. Heating of a short section say 10 yards of channel takes only millionths of a second and hence the channel section has no time to expand while it is being heated. Air heated from room temperature or from a leader temperature of a few thousand degrees to above 50,000 degrees K without having tie to expand attains a pressure considerable in excess of normal atmospheric pressure – 1 atmosphere. The initial pressure of the return stroke channel is definitely in excess of 10 atmospheres and may be 100 atmospheres or more. The high‐pressure channel rapidly expands into the surrounding air (initially at atmospheric pressure) and compresses it. This disturbance of the air propagates outward in all directions. For the first 10 yards or so it propagates as a shock wave – a major disturbance in the air which travels faster than the speed of sound) and after that as an ordinary sound wave (small compressions and expansions of the air density). The sound pulse from a short section of lightning channel lasts less than 0.1 seconds and travels at about 1090 ft/s at sea level. The thunder we hear, then, is the pressure variations induced in the air by the expansion of each part of the lightning channel (main channel and branches) due to it’s initial high pressure (Uman pg 104, 105)
- How can it be used to measure the distance and length of the lightning channel?
- The light emitted by the return stroke channel travels away from the channel at 186,000 miles/sec, and we see light almost simultaneously with channel formation. However the sound of the thunder from that channel frequently takes many seconds to reach us. The initial thunder heard comes from the point on the lightning channel that is nearest to the observer. From the time it takes the first sound to arrive we can determine how far away the lightning strike was. So 5 seconds equals 1 mile. (Uman pg 105)
- Does lightning occur without thunder? Thunder without lightning?
- Since it is the lightning channel that creates thunder, there can be no thunder without lightning. And there is no lightning without thunder as well.
- What is heat lightning? Sheet lightning?
- Heat lighting – the name given to the illumination of distant clouds close to the horizon which occurs without thunder and in the absence of a visible lightning channel. These are often too far away to hear lightning – must be within 15 miles of the lightning strike.
- Sheet lightning – name given to the intracloud discharges which light up a large cloud area simultaneously, giving the impression of a sheet of light. Sheet lightning may or may not produce audible thunder depending on its distance from the observer. (Uman pg 114, 115)
- Do gushes of rain follow thunder?
- While most rain gushes are preceded by lightning, it does not follow that lightning invariably produces rain gushes. Whether there is a rain gush or not depends, among other things, on the liquid water content of the cloud. If this is too low, heavy rain cannot form.
- Although it is possible for lightning to occur in the absence of appreciable precipitation, the two usually go hand in hand. Research shows that the greater the number of lightning discharges, the greater the rainfall. (Uman pg 120)
- What is ball lightning? Are UFO’s and ball lightning related?
- Ball lightning is the name given to the mobile luminous spheres which have been observed during thunderstorms. A typical ball lightning is about the size of an orange or grapefruit and has a lifetime of a few seconds. Visual sightings are often accompanied by permanent material damage, sounds, and odors. Ball lightning has been seen by 5 to 10% of the population. Ball lightning is usually created at or near the lightning channel and that an appreciable fraction of all cloud‐to‐ground lightning flashes may give birth to ball lightning. Since the balls generally last for only a few seconds, they cannot get too far from the mother channel. Thus ball lightning may well be common, but rarely seen. (Uman 130, 131)
- UFOs – a small percentage of the UFO reports are so similar to a certain class of ball lightning reports that they both must refer to the same “imperfectly understood physical phenomena.” These particular lightning balls are much larger, much brighter, and much longer‐lived than the typical balls. They are reported to be 10 to 20 feet in diameter, give the impression of being as bright as lightning and may last a minute or more. When such objects appear immediately after lightning it is clear that they should be called ball lightning. Sometimes, however, they appear near or in clouds or in snow without the apparent presence of lightning, and occasionally such objects are reported in seemingly clear air. (Uman pg 133)
- What is ribbon lightning? Bead lightning?
- Ribbon lightning is the name given to the optical illusion occurring when a cloud‐to‐ground lightning flash is moved sideways an appreciable distance by the wind during the time between the component strokes of the flash. Each stroke in the flash is then seen separated horizontally in space. To the eye, each identically shaped stroke (ribbon) appears to occur simultaneously. (Uman 137)
- Bead or chain lightning is a visually well‐documented phenomenon in which the lightning channel to ground breaks up, or appears to break up, into luminous fragments generally reported to be some tens of yards long. The leads are reported to persist longer than the usually cloud‐to‐ground discharge channel. However no reliable photographs of bead lightning have ever been published. (Uman pg 139)
- Has lightning any practical use?
- Nitrogen comprises about 80% of the atmosphere surrounding the earth, yet it cannot be used directly by the large majority of plants and animals until it is “fixed.” “Fixed” nitrogen is nitrogen incorporated in chemical compounds necessary to the chemical processes of life, as opposed to the relatively inert form
- of nitrogen, the nitrogen molecule, found in the air. Fixing is accomplished by special organisms in the soil and waters, industrial processes, and ionizing atmospheric processes including lightning. Nitrogen which has been fixed in the atmosphere is brought to the earth in rain. (Uman 147)
- Forest ecology
- It would seem obvious that lightning‐induced forest fires should be suppressed, but this is not necessarily the case. Until recently, frequent fires kept the California forest floor clean; the fires themselves were small and did not damage the trees. Ironically, efforts to prevent and contain forest fires in California enabled the brush to grow more thickly and now most fires are big ones. We may be indebted to ancient forest fires for California’s giant sequoias. The seedlings of these trees can germinate in ashes but are suppressed under the thick layer of needles that might cover an unburned forest floor. (Uman pg 45)