Answer:
Water cycle is also known as the hydrological cycle. It involves the water in water bodies such as ocean, river, lakes etc being heated up by the sun and then evaporations into the atmosphere. The evaporated water then condenses and falls back as rain into the water bodies.
The water body is always low during summer due to the water being heated and evaporated into the atmosphere and high during spring/winter due to rainfall and less evaporation.