Why do we see lightning before hearing thunder?
Light and sound travel at different speeds.
The short answer
Lightning heats air rapidly. Its expansion produces a sound wave: thunder. Light arrives much earlier because it travels far faster than sound. The delay does not mean thunder is created several seconds later.
An example to make sense of it
Under similar conditions, a longer wait between flash and the start of thunder usually indicates more distant lightning.
How to answer
Choose the conclusion best supported by the facts and press Check. You can revise an incorrect answer and use help whenever you wish.
Preparing the case…