One is to use Bernoulli's principle. Bernoulli's principle says that in the same fluid, the flow velocity is large and the pressure is small; Small flow and high pressure. The fluid will automatically flow from high pressure to low pressure. When passing through the trident tube (I can't see the specific picture, I can understand it myself), the low-speed water flows to the high-speed air. Water is torn into small drops by high-speed air (imagine that the water flowing out of the faucet is slow at first, and it is a water column; But then the speed gradually accelerated and became a drop by drop. These small water droplets turn into fog when they are ejected.
The second is to pump water into a thin tube to cause high-speed water flow, and the water breaks into small drops after hitting obstacles. It's like turning up the tap and blocking it with your fingers. This structure is often used in household sprayers, and the cost is low.
The third is to charge water (water is dielectric), which repels each other with the same charges and turns water into droplets. The water droplets in this method are very small. The same principle is used to paint cars.
The fourth is ultrasonic atomization. Vibration will cause "splash" on the water. Ultrasonic vibration frequency is very high, so its "wave" wavelength is very small, so its "spray"-small water droplets are also very small, and these small water droplets become fog. The throat spray machine for treating respiratory diseases in the hospital uses ultrasonic atomization.