Re: Error in Wikipedia article: Faraday's law of induction



----------------------------
"Szczepan Bia³ek" <sz.bialek@xxxxx> wrote in message
news:g5k5ng$5t8$1@xxxxxxxxxxxxxxxxxxxxxx

"Don Kelly" <dhky@xxxxxxx> wrote news:OTefk.110294$gc5.47073@xxxxxxxxxxxx

It's a bit more than this simplistic and superficial approach.
To get a high voltage between two points, it is NECESSARY that there is a
charge separation.

No. Assume that you have very small cloud composed of 10 small charged
drops. Between the cloud and the Earth is some voltage. If the drops join
together the voltagr rise.
--------
Voltage between what and what? You are hand waving.
Certainly there will be a larger electric field in the vicinity of the
larger charge. However the field at some distance from this charge may be
lower than in the original situation and the total voltage to ground may be
larger, smaller or unchanged, depending on the geometry of the situation.
The charge separation between two points is the cause of the voltage between
the two points. There are lots of ways to get charge separation and a
resultant potential difference. ---------------

This separation of charge

In contemporary science the separation of charge is used in place of
build/lowering of voltage. Current flow from high voltage to lower. Not
from more charge to less.
------------
And the reason that one point is at a higher voltage is that there has been
a charge separation. Look up the definition of potential difference (or
voltage between two points). Last time I looked, voltage was defined as the
work per unit charge to move it from one point to another. Put a path
between the two points and there is a redistribution of charge
------------- -

is the cause of the voltage difference- look at the definition of
potential difference. Updrafts, wide temperature ranges, and charge
separation due to changes in temperature followed by freezing are some of
the factors.
Suffice it to say that there are parts of a cloud that are negative with
respect to earth and parts which are positive due to charge buildup.

Are you talking about voltage?
All parts of clouds have excess of electrons.
------
This was proven wrong well over 50 years ago. Where have you been. There can
be and are regions of positive charge.

The
electric fields are related to these charges and lightning, between
earth or cloud to cloud consists of high field breakdown (in steps)
providing an ionized path for a rebalance of charge

Charge or voltage?
---------
Electric fields- volts/meter are due to charge distributions. These fields
(and their integrals- voltages between points) are due to charges. Charges
aren't due to voltages.

As for heat stored in a storm cloud- note that the temperature of the
known charge storage regions of thunderheads is generally in the -30
to -40C range. Thermal energy is involved- it is the driving force behind
the charge separation, but somehow, heat storage is rather questionable
at least. As for storage of electrons (and actually in some regions,
storage of positive ions) -isn't that a storage of charge? You are
contradicting yourself.

During condensation of steam the heat is expeled.
-------
And where is the steam in a thunderstorm? Not the clouds.
>>
Do we know the actual mechanisms involved? To some extent we do but we
certainly cannot say "this is what happens" rather than "this may be the
main mechanism" Do we know all the mechanisms and what part each of the
known mechanisms play?- definitely not.

There is a great deal of literature with respect to lightning- read it!

Meteorology is a new science. Physics is older. Lightnings folows the
physics laws. Meteorologist should read physics.
-----------------
And so should you and you might then stop putting the cart before the horse.
The literature that I refer to is related to the physics involved, known
data, and practical engineering. It is not meteorology.
Quote:
"During thunderstorms a charge separation takes place in a cloud by a
process which is the subject of several theories but is still not fully
understood....Usually positive charges drift to the upper layer of a cloud
and the bulk of the cloud becomes negatively charged"

[Gallagher & Pearman "High Voltage, Measurement, Testing and Design" Wiley
1983. ]
Included is a sketch based on actual measured charge distributions in a
cloud- and also shown in the sketch is a small region near the base of the
cloud that is also often positively charged. This particular book is a bit
dated but there are references dated later than 2000 in the Wikipedia
article on lightning (which is fairly good). The article indicates that only
about 5% of strokes are due to positive cloud charges but these are
generally much higher currents than average. However, data based on actual
measurements of over 4000 strokes in Alberta, Canada indicate about 25% are
positive, corresponding with Swedish data. Worldwide, Wiki is correct.

You may be interested in a newer book (2007) Rakov & Uman (Dept. of
Electrical and Computer Engineering, University of Florida) "Lightning,
Physics and Efffects" Martin Uman is considered a leading, if not the
foremost, authority on lightning. Also a very abbreviated non-technical
summary of lightning indicated in the following
http://thunder.msfc.nasa.gov/primer/primer2.html. This doesn't deal with
the "positive" top of cloud to ground strokes of more northerly latitudes.

There's lots of information out there if you care to look. --

Don Kelly dhky@xxxxxxxxxxxx
remove the X to answer






S*




.

Relevant Pages

  • Re: Standing-Wave Current vs Traveling-Wave Current
    ... Although the argument about no energy crossing the zero-current node is compelling, I don't feel that an adequate argument has been given to justify the wave "bouncing" theory over all other possible explanations. ... A consequence of this is that either we have a whole inductor with zero current, or the zero current point occurs between inductors, at a node to which a capacitor is connected. ... So for half of the cycle, both are putting positive charge in the capacitor, and for the other half of the cycle, both are removing charge. ... The capacitor voltage goes up and down as a result, as we can also see by looking at the voltage at this zero-current point. ...
    (rec.radio.amateur.antenna)
  • Re: Error in Wikipedia article: Faradays law of induction
    ... Between the cloud and the Earth is some voltage. ... Same total charge in Coulombs. ... proportional to the new radius of large drop. ... You are trying to compare a single large drop with 10 electrons to ...
    (sci.physics.electromag)
  • Re: Error in Wikipedia article: Faradays law of induction
    ... |> | they must send electrons in ALL directions. ... |> the middle of the cloud? ... | A storm cloud generate the high VOLTAGE not a charge. ...
    (sci.physics.electromag)
  • Re: transistors: so confusing!!
    ... It is indeed possible for a charge to move with no voltage. ... a voltage is initially required to get the charges moving ... Put a forward voltage across that diode and electrons will flow ...
    (sci.electronics.basics)
  • Re: Error in Wikipedia article: Faradays law of induction
    ... |> |> | they must send electrons in ALL directions. ... |> |> the middle of the cloud? ... |> | A storm cloud generate the high VOLTAGE not a charge. ...
    (sci.physics.electromag)