The rains are a vital component of how water moves through the water cycle of the Earth, connecting the ocean, land and atmosphere. Know where it rains, how it rains, and the character of the rain, snow, or hail that falls allows scientists to better understand the impact of rainfall on streams, rivers, escorrentieras surface and groundwater. The measurements frequent and detailed help scientists make models of and determine changes in the water cycle of the Earth.

The water cycle describes how water evaporates from the surface of the earth, rises into the atmosphere, it cools and condenses into rain or snow in the clouds, and falls again to the surface as precipitation. The water that falls on land collects in rivers and lakes, soil, and porous layers of rock, and much of it flows back to the oceans, where, once more, will evaporate. The water cycle inside and outside of the atmosphere is a significant aspect of the weather patterns on Earth.