The water cycle is like a circle-it has no beginning and no end. When the sun heats ocean water, it evaporates and forms clouds in the sky. When these particles get big enough, they can fall to Earth as precipitation in the form of rain, sleet, snow, or hail. When water hits the ground, it can change to liquid, soak into the ground, or run off and form streams or rivers. But it always makes its way back to the ocean, where the cycle "begins" again.