The size and composition of clouds and the overall amount of precipitation are some examples of measurable information that is obtained by studying the water cycle. This type of information is helpful for tracking changes in the Earth's climate.
As of 2015, scientists study the global water cycle with the help of a number of orbiting satellites. These satellites collect information about the state of all the water on Earth. At any given time, that information includes the amount of water vapor in the air, the amount of solid sea ice at the poles, the amount of water contained within clouds and the size of the particles therein. Increased water vapor in the air may contribute to overall global warming. A satellite measures the amount of water vapor in the atmosphere as well as the overall temperature, thus allowing any existing correlation to be observed.
Over time, this data forms a pattern. Researchers interpret the pattern to determine if and how the water cycle is changing over time and to make accurate predictions about how the water cycle will continue to change and affect the climate. In the short term, meteorologists may also use the data to make predictions about the weather in the near future.