What is the rule of the “balance principle” in the global water budget?

Correct answer: Global total evaporation equals total precipitation

Correct answer: B. A water budget compares water entering and leaving a system. For the whole Earth, over a sufficiently long period, the total amount of water evaporating into the atmosphere is balanced by the total amount returning as precipitation. Water may be transferred among oceans, land, ice, soil, groundwater and organisms, and a particular region can have a temporary surplus or deficit. However, at the global scale, storage does not continuously increase or decrease under a balanced long-term cycle. A is wrong because Earth is not steadily gaining water. C is false because seawater is a major source of evaporation. D is an unsupported absolute statement and is not the balance principle. Memory cue: global input and output balance, even when local stores change.