When the droplet impacts things like sand it sends shockwaves to the sand. This is the observation that is made at the University of Minnesota. The thing goes like this. When a water droplet impacts the sand. Part of the droplet will fall between the sand bites. To the point where the droplet touches sand forms the channel where air pressure is lower than around it. The water pressure pushes water below the sand bites. And then that underpressure area will pull the top of the water droplet up. And it pulls sand up. The rising top of the water causes underpressure. That rises sand up. You can see that thing in the film above this text. When water droplet touches sand it starts to spread. Then the underpressure will start to pull the droplet upward and the water tower jumps up. Until it falls back to the ground again. The thing is that water droplet acts the same way all the time. When a droplet travels through the air. It forms a channel where pressure is lower than around it. And th