I mean current flow or more exactly electrons flow when the circut is closed but when lightening strikes there isn’t any closed circuit so shouldn’t there be positively charged particles out there and if there are then how do they become neutral again?
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> isn’t any closed circuit
A circuit doesn’t always have to be completely closed at a specific moment in time for current to flow, only if you want current to flow *continuously*. Ummm I think the best way to illustrate the difference is that you’d normally think of a circuit like a water pipe spinning a little model watermill, then the water goes down the drain and into the sewer and back in the water cycle. You could however also fill a bucket from the tap, wait around for a few hours and then dump that bucket onto the watermill and thus down the drain. The circuit is effectively “closed”, there is just a disconnect in time between when one half of it is closed and when the other is, while the water is waiting in a bucket.
What happens in clouds is that charges are separated using kinetic energy, which sets up a situation where the clouds are charged to a high voltage. They then wait a bit, and at some trigger, the charges suddenly equalize with the ground again to reach a low relative voltage with the ground.
There is also the thing where “closed circuit” is kind of an abstraction. Voltage is more like pressure. Electric charge doesn’t seek to go back to their specific little house after a trip, it wants to escape a high pressure container towards some low pressure target. If you have something crammed full of charge and connect it to something that has room for those charges (is at a lower pressure), you can expect the charge to flow through the connection until both objects are at equal “pressure”.
See [the Oxford Electric Bell](https://www.youtube.com/watch?v=UtQGYz4f3YQ). The two electrodes are never directly connected. One is at a high pressure, one at low pressure. The little bell clapper ferries charge between them by equalising pressure with whatever electrode it touches and then getting repelled towards the other.
it’s not really about “closing a circuit”, the point is a bit different.
to have a current flow what you need is a “difference in potential” if there is a difference the current will flow from high potential to low (think it like a river that goes from high to low point), for example if you have two atoms like this:
+– and + one electron will be attracted to the other side and will become +- and +-.
a closed circuit and a battery/generator is necessary to keep this difference in potential that otherwise vanish immediatly.
when we talk about lighting we have ground and sky at two different potentials.
another important point is that the air normally is an electrical insulator (so no current flow) but if the potential becomes high enough air gets ionized and air becomes conductive, you need about 1kV per mm to break air as insulator, when a lighting occours it rebalance the charge and the lighting stop.
There is a circuit completed, just temporarily. Similar to static discharge, arc flash or other phenomena, the air itself can be your conductor if the difference in potential (voltage) is great enough. Lightning happens when you have enough potential between the source and where it strikes. It’s not a sustained transfer because as soon as you start moving electrons, you are dissipating the potential.
Let’s say you have a cloud with a lot of electric charge, and the ground with either no charge or the opposite charge. It’s often another cloud on the other end, but never mind.
As you accumulate more charge in the cloud, you increase the voltage between the cloud and the ground, which is a measure of how badly the charges want to get from one place to the other.
The only thing between the cloud and the ground is air, and air is usually a pretty good insulator. Insulators aren’t perfect, though. If you put enough voltage across them, they can break down and allow current to flow.
The flow of current is in the direction that tries to neutralize the charge imbalance, so it’s not long before there’s no charge left to make this happen, the lightning stops, the electrical separation is reestablished, and the charge can start accumulating again
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