A build up of charge in the cloud results in the opposite charge building in the ground beneath it. When the charge is big enough and a path is found to ground (sometimes initiated by a passing high speed ion) a discgarge to ground and back up occurs. read more
It’s not that lightning is faster than thunder, but that the effects - a flash of light and a sound clap of thunder, the former travels much faster. Therefore for a distant lightning strike, you will see the flash first, followed as much as several seconds later the thunderous clap of the thunder. read more
Lightning is seen earlier than thunder because light travels much faster than sound. The roar of thunder is the result of a shock wave produced when lightning super-heats the air through which it passes, causing that air to expand very rapidly. read more
Any sound you hear is made up of vibrations. The vibrations travel as a sound wave through the air, until they reach your ear. read more