How does hydroelectric (dam) power work?
Light from the sun strikes water molecules on the Earth. This electromagnetic potential energy (all light is, really) excites the water molecules, and turns them into gas (something we see as evaporation). With more kinetic energy, the water molecules bounce up towards the atmosphere, and eventually condense as clouds. When it rains, much of the water falls in the mountains, and flows downward into rivers. These rivers are dammed, and the water flowing down spins a turbine. In short: 1.
