Depending on how the spark gap is set, usually one or two sparks occur at the peak of each half-cycle of the mains current, so there are more than a hundred sparks per second. Source: Internet
A move down yields two half-cycles horizontally and a half-cycle vertically. Source: Internet
Commercial applications are for long half-cycle storage such as backup grid power. Source: Internet
For each half-cycle, part of the LED emits light and part is dark, and this is reversed during the next half-cycle. Source: Internet
For example, moving right one from the top-left square yields a half-cycle increase in the horizontal frequency. Source: Internet