Why do some water fountains produce two streams of that merge into one?

The Bernoulli effect is a principle in fluid dynamics that describes the relationship between fluid velocity, pressure, and height. It states that the faster a fluid flows, the lower its pressure, and vice versa.

In the case of a water fountain, the water is pumped up to a reservoir at the top of the fountain. As the water falls down, it picks up speed and its pressure decreases. This creates a difference in pressure between the top and bottom of the fountain, which causes the water to flow out of the nozzles.

The shape of the nozzles is designed to create two streams of water that merge into one. This is done by creating a curved surface that directs the water in a specific way. As the water flows out of the nozzles, it follows the curve of the surface and merges into a single stream.

The Bernoulli effect is also responsible for other phenomena, such as the lift on an airplane wing and the Magnus effect on a spinning ball.