How does lightning and thunder happen?

Question

How does lightning and thunder happen?

Answer 1

When thunderstorms form the tops of the clouds are very cold and contain ice.  Water and ice when being blown around in the sky develop electrical charges the same way you do in the winter time when you walk across the carpet and get a shock when you touch metal.

As the water and ice continue to get blown around in the sky the electrical charge keeps building up more and more, however, air is a good insulator from electricity, so it prevents the electrical charge from going anywhere for awhile.

The ground is also electrically charged and that is what is meant when we say you need a good "ground" for electricity to flow through a circuit.  With this in mind, remember that the clouds are building up more and more electrical charge from the wind blown ice and water, and the ground is building up more of an attraction to this charge.

This attraction keeps pulling the electricity down from the clouds, but until it reaches the ground it cannot make a connection.  Finally the charge is so powerful that it pushes all the way through the air to the ground and an electrical circuit is established.  The electrical charge from the clouds flows down through this connection (same was as electricity flows through the wires of your house) into the ground.  Immediately afterwards, all the charge built up in the ground flows up into the clouds to complete the exchange of current.

When you see a lightning bolt "flicker" you are actually seeing several exchanges of electrical current from the clouds to the ground and back again.  The dimmer part is the discharge going from clouds to ground, and the bright, thicker flash, is the return stroke of the electricity going from the ground back up to the clouds.

After the lightning has struck, the clouds and ground are discharged and the whole process starts over again.

Thunder is caused by the heat of the lightning bolt.  Lightning is very hot, about five times hotter than the surface of the sun, or about 50,000 Degress!  The hot lightning bolt heats up the air it passes through, and this super hot air expands very fast into the cooler surrounding air.  The sound of thunder is the sound the air makes when it collides into the cooler surrounding air next to it.  It's almost like a mini explosion of air.