Meteoric water, derived from precipitation such as snow and rain, includes water from lakes, rivers, and ice melts, all of which indirectly originate from precipitation. The journey of meteoric water from the atmosphere to the Earth's surface is a critical component of the hydrologic cycle. 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 Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

s. Most groundwater is, in fact, meteoric water, with other forms such as connate water and magmatic water playing minor roles. Connate water, trapped in rock strata at the time of their formation and often saline due to its origins in ocean sediments, and magmatic water, which accompanies magma intrusion from great depths and influences mineralogy, contrast with meteoric water's journey through porous and permeable layers, including bedding planes and fractures.

Properties and significance

Meteoric waters are distinguished by their minimal

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

and their initial

acidity An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

, characteristics that change based on their interactions with subsurface environments. The acidity of meteoric water, driven by atmospheric contributions of humic, carbonic, and nitrous acids, plays a critical role in the geochemical processes of soil and subsurface environments. As these waters percolate through soil and rock layers, especially

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and Dolomite (rock), dolomite rock (also kn ...

s, their capacity to neutralize acidity influences the solubility of minerals, the availability of nutrients, and the transport of metals. The Global Meteoric Water Line (GMWL) is a cornerstone concept in understanding the behavior of meteoric waters. Established by Harmon Craig in 1961, the GMWL delineates the global annual average relationship between the

isotope ratio The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundan ...

s of hydrogen and oxygen (oxygen-18 and deuterium) in natural meteoric waters. This isotopic signature is invaluable for tracking water masses in environmental

geochemistry Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

and

hydrogeology Hydrogeology (''hydro-'' meaning water, and ''-geology'' meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rock (geology), rocks of the Earth's crust (ge ...

, offering insights into water cycle dynamics, climatic conditions, and the origins of water samples.

History

The term "meteoric," referring to the direct atmospheric origin of this water, shares its root with the science of

meteorology Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agricultur ...

. It stems from a Greek word initially associated with astronomical phenomena. However, the scope of the term expanded significantly following the publication of

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

's "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

meteor A meteor, known colloquially as a shooting star, is a glowing streak of a small body (usually meteoroid) going through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a ...

s, which were originally believed to be weather-related events.

References

{{cite web , title= Glossary of Meteorology , publisher=

American Meteorological Society The American Meteorological Society (AMS) is a scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance the atmosph ...

, url=http://amsglossary.allenpress.com/glossary/ , accessdate=2006-05-13 Precipitation

Properties and significance

History

See also

References