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Voltage of thundercloud as point charge

Hey,

Theory: The voltage of a thundercloud is too low to ionize air particles and to produce a thunder.
Particles of cosmic radiation are the trigger.

I calculated whether the voltage of a thundercloud is enough to ionize air particles but the voltage was always to low. So I wanted to know how high the voltage is when we consider the cloud as a point charge. I looked for the value on the internet but I didnt find anything. Do you can tell me a number?

If you don't find anything then I have another question for you ;),

Everytime a thunder emerges, it porduces x-rays - is it true?

and the last question:

Where is an optimal entry point for a thunder?

You do not need to answer all question - but if you can I wont stop you :).
And sorry for my bad english. If anything is unclear for you, please ask me!
 

berkeman

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Hey,

Theory: The voltage of a thundercloud is too low to ionize air particles and to produce a thunder.
Particles of cosmic radiation are the trigger.

I calculated whether the voltage of a thundercloud is enough to ionize air particles but the voltage was always to low. So I wanted to know how high the voltage is when we consider the cloud as a point charge. I looked for the value on the internet but I didnt find anything. Do you can tell me a number?

If you don't find anything then I have another question for you ;),

Everytime a thunder emerges, it porduces x-rays - is it true?

and the last question:

Where is an optimal entry point for a thunder?

You do not need to answer all question - but if you can I wont stop you :).
And sorry for my bad english. If anything is unclear for you, please ask me!
Welcome to the PF.:smile:

Is this for schoolwork/homework, or just general questions? I can move this from the Homework forums to the more general physics forums if it is not for schoolwork.

Also, can you please post a few links to what you have been reading so far on the Internet about thunder and lightning? That will help us to help you understand the mechanisms of lightning better.
 
Thank you!

The last question is for my homework the other two not.
I watched a video about it "Quarks und Co Blitze". A electron with ebough energy can ionize an atom. The free electron ionize another atom and so on. The heat of this proccess is what we see (the thunder). Thats how I understood it. The first two question were the topic of the video - I want to proof it.
 

berkeman

Mentor
54,767
5,020
Thank you!

The last question is for my homework the other two not.
I watched a video about it "Quarks und Co Blitze". A electron with ebough energy can ionize an atom. The free electron ionize another atom and so on. The heat of this proccess is what we see (the thunder). Thats how I understood it. The first two question were the topic of the video - I want to proof it.
Maybe read through the wikipedia article on lightning to see if it helps. If not, post a link to the reading and ask specific questions about what is confusing you. :smile:
 

Drakkith

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I calculated whether the voltage of a thundercloud is enough to ionize air particles but the voltage was always to low. So I wanted to know how high the voltage is when we consider the cloud as a point charge. I looked for the value on the internet but I didnt find anything. Do you can tell me a number?

We estimate the voltage relative to the Earth inside thunderstorms and at cloud top from balloon soundings of electric field through convective regions and stratiform clouds. These are the first estimates we know of that give the voltage through the entire depth of storm clouds. Cloud top voltages were available for 13 soundings and ranged between −23 and +79 MV, with an average of +25 MV. The average cloud top voltage among the nine cases with positive values was +41 MV. These values support the Wilson [1920] hypothesis that thunderstorms drive the global electric circuit. The average cloud top voltage above electrified stratiform clouds was +32 MV, so these clouds may also make a substantial contribution to the global electric circuit. Within clouds the voltage values ranged between −102 and +94 MV in the 15 soundings. The voltage difference associated with intracloud and cloud-to-ground lightning flashes estimated from our soundings is in the range of about 20 to 130 MV.


From here: http://onlinelibrary.wiley.com/doi/10.1029/2000JD900640/abstract

In the paper, they have the electric field strength of several thunderstorms graphed, and it looks like it ranges upwards to about ±100kV/m, which should be sufficient to ionize the air in the presence of impurities:

The electrical breakdown of air (ionisation) normally take 3,000,000 volts per metre, however with the ambient electric fields of a charged thunder cloud and impurities in the air, ionisation normally takes place at much lower voltages during a storm. Lab tests have shown a leader will advantage if the tip of the streamer is about 4.5kV (4500v) for a negative charge and 5.5kV (5500v) for a positive charge.

From here: http://www.aharfield.co.uk/lightning-protection-services/about-lightning

Everytime a thunder emerges, it porduces x-rays - is it true?
You mean lightning. Thunder is the sound that a lightning strike makes. A lightning bolt is the actual discharge of current from the cloud to the ground, from the cloud to another cloud, or from one part of the cloud to another. A lightning strike is the event of a lightning bolt striking a particular location.

And yes, I believe that lightning generates x-rays.

Where is an optimal entry point for a thunder?
What do you mean by "entry"?
 

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