Crazy pool vortex

The video explores the formation and behavior of vortices in water, specifically focusing on the creation of perfect black circles on the pool's bottom. It explains how vortices form due to differences in fluid speed and how they maintain angular momentum. The video introduces the concept of a half vortex ring, similar to a smoke ring, and discusses how these vortices create dark spots by acting as lenses that focus light. Practical tips for recreating these phenomena at home are also provided.

What is the significance of the half vortex ring created in the water?

Describe the role of gravity, centripetal forces, and surface tension in the formation of dark spots.