A thunder is the loud and booming sound that occurs during an electrical storm. It is caused by the rapid heating and cooling of the air as a lightning bolt travels through the atmosphere.
When a lightning bolt streaks across the sky, it heats the air to extremely high temperatures, causing rapid air expansion.
This expansion creates a shockwave that propagates through the air and reaches our ears as a deafening noise. Thunder is a sign that an electrical discharge has occurred in the atmosphere during a storm.
