Apa yang dimaksud dengan Siklus Hidrologi?

conceptual animation of the hydrologic cycle, illustrated with a mountainous basin with drainage into an ocean. Arrows point upward from the ocean, toward developing clouds over the land surface and mountains. Precipitation develops over the moutains, and arrows show the resulting runoff being channeled throughout the streams, lakes and within various layers of the ground.
Click to play animation.

Siklus hidrologi sering disebut siklus air. Siklus ini menggambarkan gerakan air secara vertikal dan horizontal baik dalam bentuk uap air, cairan, atau padat, yang berada di atas permukaan bumi, dalam tanah, maupun di atmosfer dan lautan.