Question: what causes thunder

Zena Hadjivasiliou answered on 14 Mar 2015:

The sound of thunder is caused by lightning. The lightning has lots of energy and is super hot. The heat from the lightning is transferred to the air that surrounds it in the sky but the lightning moves so quickly that there is not enough time for the air to expand when it becomes hot and so the heated air ends up being massively compressed (so there is a loooot of pressure in it). This compressed air then explodes and forms a shock wave of compressed air particles, which what sound is! Because this explosion happens due to a lot of pressure and energy, the sound it generates is very loud!