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29

Yes, it's possible. Though, I'm sure the engineers of the Sears Tower took that into account. Catastrophic failure of the rod is pretty straightforward. Lighting is a ton of electrical current, and the rod has some resistance. Current through a resistance makes heat by Joule heating, which says that the power is proportional to the resistance times the ...


24

This is an interesting question. Unfortunately, the answer is probably no for two reasons. There is a nice way of telling how far away a lightning strike was by counting the seconds before the thunder reaches you though. First let me tell you why your method probably won't work, then I'll tell you how to calculate the distance based on the time of arrival ...


17

1) yes, it basically will find a non-optimal solution. At every point, the top of the ray looks for the bigger potential gradient, the charge in the surrounding volume grows, polarizing surrounding material (air, in this case) until a bigger gradient shows up and the ray continues over that direction. This is why the lightining path looks like a jigsaw; its ...


15

I think yes, you can get some distance information from analyzing the thunder sound. I am basing this mostly on having personally heard many thunderclaps, both far and near, of reasonably known distance to the lightning. Anyone that has ever experienced a near (100 m or less) thunderclap can tell you it sounds a lot more "sharp" than a distant one, not to ...


12

Most probably yes; wireless devices are not grounded, so they are not lighting rods of any kind as it is frequently assumed. There are some theories that cell phones somehow attracts lightnings by the field they produce, but the theory behind is weak. Experimental evaluation is very hard, since lightning hits are quite rare, such events are guided by ...


11

In fresh water what makes lightening so dangerous to a swimmer is that most of the current travels on the surface of the water, so rather then getting a $1/r^2$ falloff in current density, you see a $1/r$ falloff. Obviously eventually it will be conducted down into the mass of the water, but this takes a many meters. In salt water, this should happen much ...


10

I can't point to a definitive reference, but my recollection is that thunderstorms are associated with a lower layer of warm air rising rapidly through an upper layer of cold air. It's the rapid vertical transport that generates the static charge and hence the lightening. In winter it's rare to get these atmospheric conditions. So it's not that there's ...


10

Here's a crude way to look at the problem: Suppose there are $N$ wires. Each has resistance $R$, common potential difference $V$ and are connected in parallel. So the current through each wire is $I = \frac{V}{NR}$. Let's imagine a hypothetical wire formed by sea water which has a length, $L$ and cross sectional area, $S$. There are approximately ...


8

I have always assumed it could be put down to a small set of causes: The stroke may have a physical extent and geometry that leads to a perceptible duration between the arrival of the sound due to the near part of the strike and that due to the far part. That is, what Georg said. If the geometry of the terrain is right you may be hearing echos off of cliff ...


8

AM radio typically transmits at around 1 MHz, FM radio at about 90 MHz. Measurements of the RF spectrum of lightning strikes show a falloff with frequency of about 20 dB per decade in that frequency range, so with FM about 2 decades above AM, you'd expect AM to have about 40dB higher interference from a lightning strike. In addition to that, FM signals ...


8

At sufficiently high voltages almost everything conducts due in part to quantum tunneling of electrons. An insulator has a breakdown voltage which is the field strength required before it will start conducting. Related to the breakdown voltage is the dielectric strength which is the minimum voltage over distance ($\mathrm{V}/\mathrm{m}$) before a material ...


7

Yes, if it is not a plastic covered car it is an effective Faraday cage. If the tires are such that the car is insulated electrically, if it is hit it will take some time to discharge to the ground, but still the passengers would be safer than standing next to it outside. I have learned that modern tires are particularly constructed so that the static ...


6

Basically: no cheap, efficient, large-scale battery technology exists. This question gets asked in the world of intermittent renewable energy generation all the time, but it is even harder for lightning because of the extermely high power of the energy burst, so that's an extra problem to solve on top. Also, how do you predict where it will strike? Build a ...


6

In answer to your second question: "Now going with my b) reasoning, wouldn't you be just as safe standing next to a giant conductive pole (i.e. a lightning rod)? Wouldn't the lightning just go through the lightning rod and you'd be 100% safe?" No. A lightning strike can carry a high current, up to 200 kiloamps has been recorded. Not only can the current ...


6

Electric Conduction: At atmospheric pressure, air and other gases are poor conductors (Insulators) of electricity. 'Cause they don't have any free electrons to carry current. But, once free electrons are produced in gas by ionization (They become plasmas), discharge of electricity through gases appears. This could be done in many ways such as applying large ...


6

The majority of the energy is dissipated in the travel through the air from the cloud to the ground. The energy goes into heating the air and generating the shockwave that we hear as thunder. I can't give you a single definitive refernce for this, but Googling "energy dissipation lightning" will find lots of relevant articles. You can understand why this is ...


6

Yes it is: lightning in slow-mo In general, both are possible, see: types of lightning


6

I presume you did not see the flash, so cannot use that as a timing mark. From Wikipedia "The dependence on frequency and pressure are normally insignificant in practical applications. In dry air, the speed of sound increases by about 0.1 m/s as the frequency rises from 10 Hz to 100 Hz. For audible frequencies above 100 Hz it is relatively constant. " You ...


6

The lightning is just electricity, a huge burst of electrons that try to find the path of least resistance through the molecules of the atmosphere to the ground. The electrons come from many different places in the clouds and the atmosphere is not homogeneous: there are differences in humidity, temperature, density, particle count, velocity, etc., and this ...


6

Why is it never just a straight line? I think it can be interesting to answer both questions and add a few interesting details to the answer already given. Electrons move in a straight line only in vacuum, where they meet no obstacles. What happens here is the same that happens with a river: the water of a waterfall goes in a straight line because it ...


6

Higher frequencies attenuate faster in air than lower frequencies. The further away a lightning flash the less high frequency components will reach your ear


5

The wikipedia article is quite good on this subject. For any discharge in the air the molecules of the air must be ionized. This ionization happens during thunderstorms because of the high static electric fields carried by the clouds which generate "streamers", i.e. paths for the electrons to flow downwards. Corresponding streamers are formed by conductors ...


5

It is difficult to measure, but a bulk of it's energy is not spent in ionizing the atmosphere or in the sound wave but in the movement of charge itself. However lightening labs will measure a variety of factors to characterize the strike. They launch small rockets carrying a small wire or sometimes emit some conductive ionized gas which triggers a strike ...


4

The mechanism by which lightning is produced is complex and imperfectly understood, but we know moisture is important in two respects: Heat is released when water vapor in the air condenses into liquid drops, and this heat helps provide energy to the thunderstorm. Interactions between supercooled liquid water droplets and ice crystals in the upper ...


4

It depends on how you define "lightning". When electrons flow from clouds to the earth, ionizing the air and producing light, does your definition include the electrons, the air, the plasma, the light, or a subset? Pedantically speaking, I would say that lightning is the flow of electrons, and to me a flow is an abstract idea (the action of moving in a ...


4

This video illustrates how a candle flame conducts a high voltage (10,000 volts). Although the ion density is small in a candle flame, they are sufficiently present to conduct electricity.


4

A modern wireless electrical device should be perfectly safe, all it is is putting a metal piece near your ear, basically giving you the same chance of being hit by lightning as any other time. Older (Or more accurately, larger) technologies with larger antennas might work as a lightning rod, and thus give you a somewhat higher chance of being hit. ...


4

A lightning bolt produces hot gasses (30,000 °C). This results in very high pressures. This pushes away surrounding material. When the material cools, the empty region where the current passed is left empty for the same physical reasons that a piece of wood retains the imprint of a nail. Some of the sand is melted and solidifies before it can flow back into ...



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