Faraday shown that magnetic field can produce sparks and claimed electricity and magnetism are related, when he shown light over the gaps there are more sparks being produced! what's happening? I imagine there is a powerful electric field that cause the air to become ionised and a conductor of electricity but why shine photon at it can cause more sparks to be generated? also are there more lightning in the day than at night?
If the light contains some ultraviolet in the mix, then it becomes possible for the UV photons to hit the metal spark electrode faces and eject photoelectrons from them, thereby triggering an ionization avalanche that leads to a spark forming between the electrodes. More UV = more sparking.
This effect is so strong that researchers who are studying spark breakdown dynamics will often shine UV light into the breakdown gap to ensure that when they turn the voltage on in the apparatus that ionization will promptly start on every experimental run.
This has nothing to do with lightning prevalence, day versus night, because the breakdown mechanisms that are active in the case of lightning do not rely on the presence of UV light.