This is called rectification, and rectifier diodes are most commonly used in low current power supplies. A switching diode is most often used to turn a circuit on or off, and band switching diodes are used for switching high frequency band signals.
Thunder occurs when energy from lightning heats and rapidly expands the air. The resulting sound wave gets heard as thunder. While lightning and thunder occur at roughly the same time, lightning travels at the speed of light, or at 186,000 miles a second, while thunder travels at the speed of sound, equivalent to one-fifth of a mile in one second. People see the lightning long before they hear the thunder.
When this happens, a stream of negative charges pours down towards a high point where positive charges have clustered due to the pull of the thunderhead. The connection is made and the protons rush up to meet the electrons. It is at that point that we see lightning and hear thunder. A bolt of lightning heats the air along its path causing it to expand rapidly. Thunder is the sound caused by rapidly expanding air.