While a significant portion of this water reaches the sea through surface flow, a considerable amount gradually infiltrates the ground, continuing its descent to the zone of saturation and becoming an integral part of groundwater in aquifers.
Meteoric waters are distinguished by their minimal salinity and their initial acidity, characteristics that change based on their interactions with subsurface environments.
Established by Harmon Craig in 1961, the GMWL delineates the global annual average relationship between the isotope ratios of hydrogen and oxygen (oxygen-18 and deuterium) in natural meteoric waters.
The term "meteoric," referring to the direct atmospheric origin of this water, shares its root with the science of meteorology.
In this seminal work, which covers a broad range of earth sciences, Aristotle extended the term's application beyond astronomical discussions to include any significant phenomena observed in the sky, such as meteors, which were originally believed to be weather-related events.