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    Basically i am doing the homework question, the answer tells me :

    "a very strong electric field ionises air by taking electrons from it. the electric field in the air becomes stronger due to the clouds becoming more charged. the air discharges between the cloud and the ground "

    what does this mean? does air = Cloud

    is the cloud negative?

    help!
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    (Original post by Mohid Khan)
    Basically i am doing the homework question, the answer tells me :

    "a very strong electric field ionises air by taking electrons from it. the electric field in the air becomes stronger due to the clouds becoming more charged. the air discharges between the cloud and the ground "

    what does this mean? does air = Cloud

    is the cloud negative?

    help!
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    Its much like a parallel plate situation where as the cloud is charged there is a strong linear electric field between the cloud and the ground. There is therefore a potential difference between the cloud and the ground (cloud is negative and ground relatively positive). The air can only insulate up to a certain value for the field strength and if this is exceeded boom electrostatic discharge


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    (Original post by tmorrall)
    Its much like a parallel plate situation where as the cloud is charged there is a strong linear electric field between the cloud and the ground. There is therefore a potential difference between the cloud and the ground (cloud is negative and ground relatively positive). The air can only insulate up to a certain value for the field strength and if this is exceeded boom electrostatic discharge


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    so are clouds conductors, and the air is an insulator right?
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    (Original post by krisshP)
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    where does the clouds get their Negative charge from?
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    (Original post by Mohid Khan)
    so are clouds conductors, and the air is an insulator right?
    Yeah it's a similar to a capacitor. The air insulates the cloud and the ground (like the insulator between two plates). As the charge builds up in the cloud (as to how this happens is still debated to this day) it reaches the required electric field strength the air ionises which separates positive ions and electrons in the molecules. Since the electrons are now free from their respective molecules this makes the air very much like a metal with free charge carriers around positive ions. The charge difference can neutralise by a current flowing via these freed electrons from the cloud to the ground. All happening in a ridiculously short amount of time obviously.


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    (Original post by Mohid Khan)
    Basically i am doing the homework question, the answer tells me :

    "a very strong electric field ionises air by taking electrons from it. the electric field in the air becomes stronger due to the clouds becoming more charged. the air discharges between the cloud and the ground "

    what does this mean? does air = Cloud

    is the cloud negative?

    help!

    Please read this:

    http://www.vivaxsolutions.com/physic...induction.aspx
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    cheers
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    I will put it this way: the thunder cloud has a negative charge at the bottom and a positive charge at the top due to electric activities at the upper atmosphere. Then it induces positive charges on the objects on the ground; the sharper the points, the more electron accumulate at those points. That's why you are not supposed to carry sharp objects during thunder storms, including umbrellas with sharp tops.
    Then suddenly a massive spark takes place between the cloud and an object on the ground. This is a thunderbolt. We hear sound later due the difference of the speed of light and that of speed, although they take place simultaneously.
    Get a clear picture of electrostatics including induction rather than focussing only on lightning.
    Here is further help:
    http://www.vivaxsolutions.com/physic...induction.aspx
    Drop a line if you are pleased with the response.
 
 
 
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