is the rumbling or crack of sound that can usually be heard from the
sky during a storm. Thunder is caused because lightning heats up the
air, to about 30 000ºC, causing it to expand
quickly. The rumbling occurs as the sound passes through atmospheric
layers at different temperatures.
far away is a thunderstorm?
estimation of how far away a storm is can me made by counting the
number of seconds between a lightning flash and the start of thunder.
If you divide this number by five, the answer is how many miles away
the storm is from you.