what are lightening and thunder ?

Answer 1

There are a few different theories why (which I won't go into), but in a thunderstorm positive charges gather at the top and negative gather at the bottom of a cloud.
Since opposite charges attract, the negative charges in the bottom of a cloud 'pull' positive charges to the surface of Earth creating a positively charged surface (as well as buildings, trees, people etc) as the storm moves along. Air is a poor conductor so the charges can't meet right away, they are still stuck at the cloud base and the Earth's surface.
Negative charges in the cloud jump from air molecules 50-100 meters at a time towards the ground in all different directions, creating 'stepped leaders'. Eventually one of the 'leaders' negative charges reach the ground creating a path for all of the negative charges to rush from the cloud to the ground. This allows an electric current to rush from the ground to the cloud, which is what we see as lightning - and this explains why lightning appears jagged.
When you look at a picture of lightning, you usually notice one bright 'bolt' surrounded by smaller jagged branches jutting out around it. Those are stepped leaders that didn't make it to the ground.

Lightning heats the air surrounding it to a temperature exceeding 50,000 degrees F so quickly, that the air surrounding the 'channel' that the lightning strike followed has a very high pressure. That air expands into the air around it, then collapses, creating a shock wave which turns into a sound wave which is what we hear as thunder.
Thunder has the sound of a "crack", but as you are standing farther away from the lightning strike, the different densities of air cause the sound wave to bend, and thunder sounds more like a rumble. And thunder occurs at the same time as lightning, but sound travels slower than light so we hear thunder after lightning, a bigger time difference between the two the further you are from the lightning strike.
I've answered this kind of question before, so I copied my own answer over for you. I hope this helps.

Answer 2

Lightning is the discharge of electricity. This occurs because the air is an insulator and insulators are poor at arranging the electrons. When this happen, so much electrons build up an excess that it become greater than the air, and this results in what is a discharge. Thunder is just the soundwaves that are produced by lightning. When lightning flashes tremendous amounts of heat is released around 40,000 degrees Celsius, which heats the air. The heat air quickly expands and cools on contract. Once the air cools then the air molecules will collide and rub against each other that creates soundwaves and make thunder.

Answer 3

I'm not sure about lightning. But thunder is the sound of the lightning making contact with the earth. It comes a few seconds after lightning strikes because light travels faster than sound.

Answer 4

lightning is the strike and the thunder is the sonic boom from the strike break the sound barrier.

Answer 5

a light from space

Answer 6

lightnig is sparks and thunder is clouds clashing together