0
$\begingroup$

Is an electromagnetic pulse sufficient to account for the complete dscharge of an aircraft struck by lightning?

$\endgroup$
2
$\begingroup$

It is not quite clear what you mean by an electromagnetic pulse and why you seem to assume that an aircraft struck by a lightning will be completely discharged.

So, I'll try to describe what I believe might happen during a strike and, hopefully, it'll clarify matters for you.

As clouds get charged (due to processes outside the scope of this question), they are "looking" for an opportunity to get rid of their charge by sharing it with any conductors close enough to be reached, like earth or other clouds or an opposite side of the same cloud that happen to carry a charge of an opposite sign.

From this prospective, a passing aircraft is a legitimate target, just like another cloud but even better considering that its skin is highly conductive and its geometry includes a lot of sharp edges: both of these features will facilitate the formation of strong electrical fields and the initiation of a discharge.

When a discharge or a lighting strike between a cloud and an aircraft occurs, the aircraft ends carrying a fraction of the charge lost by the cloud, i.e., it will be charged - not discharged.

It is likely that an aircraft was carrying some charge before the strike had occurred.

If so, such charge could make the strike more or less likely, depending on the sign of that charge and the sign of the charge in the cloud, but, once the strike occurs, the end result won't depend on the magnitude of that initial charge - it'll rather be dependent on the magnitude of charge in the cloud and on the relative effective capacitance of the cloud and the aircraft.

This is because the initial charge on the plane is likely to be insignificant with the charge in the cloud and will be, so to speak, lost in transaction.

Even in the absence of charged clouds, a charged aircraft will gain and lose charge continuously as it goes. I suppose that, when it passes through a neutral cloud, it could discharge completely, but I am not sure if such discharge could be violent enough to qualify as a lightning strike.

$\endgroup$
  • $\begingroup$ Thanks! However, I am not sure my question is fully answered. Does the $\endgroup$ – michael nettleton Apr 30 '18 at 14:24
  • $\begingroup$ Could you complete your question please - it seems to be truncated? $\endgroup$ – V.F. Apr 30 '18 at 15:27
  • $\begingroup$ Sorry! Am I correct in assuming the rate of dissipation of charge on an aircraft depends onthe difference in charge between it and the surrounding cloud? $\endgroup$ – michael nettleton May 5 '18 at 16:16
  • $\begingroup$ It seems that you are not talking about a strike, but rather about a "non-violent" or gradual dissipation or flow of charge. Yes, the rate of such dissipation, facilitated by dissipators installed on most aircraft, depends on the strength of the field and therefore on the difference of potentials between the aircraft and surrounding clouds and therefore on the difference in the charge levels. $\endgroup$ – V.F. May 5 '18 at 16:32
  • $\begingroup$ Actually, I was thinking of a direct strike on an aircraft. What is he essential difference between charge dissipation beween a a direct strike and a non-violent event? $\endgroup$ – michael nettleton May 7 '18 at 15:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.