"A cat-o’-nine-tails of lightning arched out across the sky"

A lightning strike with branching paths of electricity
Creative Commons Attribution Share AlikeA lightning strike with branching paths of electricity - Credit: David Selby/wikimedia commons
A cat-o’-nine-tails is a multi-tailed whip made of nine knotted cords, designed to inflict intense pain. The metaphor is referring to the branching paths of electricity often seen in a strike of cloud-to-ground lightning.

A cat-o'-nine-tails
GNU Free Documentation LicenseA cat-o'-nine-tails - Credit: OwenX/wikimedia commons