Blowing bubbles is a question of how a liquid film—typically soapy water—interacts with an imposed flow of an external fluid, which is air in the case of bubble blowing.The shape of the bubbles is determined by surface tension. This is what holds the bubble together. It’s also what allows you to fill a cup with water over the brim without spilling. The bubble always tries to make the shape with the minimal surface area. In the free air, this is always a sphere.
Saturday, first of December 2018, Amsterdam