Fog Drip
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Fog drip is water dripping to the ground during
fog Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenc ...
. It occurs when water droplets from the fog adhere to the needles or leaves of trees or other objects, coalesce into larger drops and then drop to the ground. Fog drip can be an important source of moisture in areas of low rainfall, or in areas that are seasonally dry.


Studies in the United States

* On the leeward slopes of
Maui Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui is one of ...
, the original
dryland Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by transpiration by plants (evapotranspiration). The United Nations Environment Program defines drylands as tropical ...
cloud forests were destroyed during the 19th century but historically were inhabited by
native Hawaiians Native Hawaiians (also known as Indigenous Hawaiians, Kānaka Maoli, Aboriginal Hawaiians, or simply Hawaiians; , , , and ) are the Indigenous Polynesian people of the Hawaiian Islands. Hawaiʻi was settled at least 800 years ago by Polynesian ...
, so there must have been water sources. Isotopic (
Oxygen-18 Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharm ...
) analyses of one of the few remaining areas of native forest, at elevation in the fog belt, found that fog drip was a major component of stream flow and shallow ground water at higher altitudes in the watershed. * On arid
Santa Cruz Island Santa Cruz Island (Spanish language, Spanish: ''Isla Santa Cruz'', Chumashan languages, Chumash: ''Limuw'') is located off the southwestern coast of Ventura, California, United States. It is the largest island in California and largest of the ei ...
, a study of the southernmost
Bishop pine ''Pinus muricata'', the bishop pine, is a pine with a very restricted range: mostly in California, including several offshore Channel Islands, and a few locations in Baja California, Mexico. Stands of Bishop Pine are also found in Point Reyes Nat ...
(''Pinus muricata'') forest in
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
found that summer cloud shading and fog drip mitigate the effects of summer drought. Even though fog cover in summer only occurs 15% of the day, this minor amount of fog enabled trees and soil microbes to grow at an increased rate. However, winter rainfall was the primary driver of summer tree growth, which is only aided by reduced soil evaporation in summer due to fog drip. Cloud cover and fog drip have enabled this relict pine forest to persist from prehistoric times when the climate was wetter. * In the Bull Run River,
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
, fog drip from mature
Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...
(''Pseudotsuga menziesii'') forest adds of moisture per year, a 41% increase over that from rain and snow, and importantly, of all moisture in the dry May to September season. * In
California Coast Ranges The Coast Ranges of California span from Del Norte County, California, Del Norte or Humboldt County, California, south to Santa Barbara County, California, Santa Barbara County. The other three coastal California mountain ranges are the Trans ...
, a single
Coast redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995: 606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coast ...
(''Sequoia sempervirens'') can "douse the ground beneath it with the equivalent of a drenching rainstorm and the drops off redwoods can provide as much as half the moisture coming into a forest over a year". Dawson reported that in a study of northern California redwood forests, 34% of annual hydrologic input was from fog drip. In areas where trees had been cut down, the average annual input from fog was only 17%, proving that the redwoods were required for the fog moisture input to the ecosystem. In an
Occidental, California Occidental is a census-designated place (CDP) in Sonoma County, California, United States. The population was 1,132 at the 2020 census, up from 1,115 at the 2010 census. History Founded in 1876, Occidental was a stop on the North Pacific Coast ...
study beneath a single Douglas fir on a ridge dividing the moister western slope of the California Coast Range from the drier eastern slope, moisture collected under the tree averaged versus in an adjacent open meadow. On Inverness Ridge in
Point Reyes National Seashore Point Reyes National Seashore is a park preserve located on the Point Reyes, Point Reyes Peninsula in Marin County, California. As a national seashore, it is maintained by the US United States National Park Service, National Park Service as an ...
fog drip from Douglas firs in summer may add to the otherwise of annual average rainfall. Further south, on Cahill Ridge on the
San Francisco Peninsula The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is Los Altos and Mountain View, ...
(between Pilarcitos Creek and Crystal Springs Reservoir) at an altitude of , Oberlander measured fog drip beneath
Tanoak ''Notholithocarpus densiflorus'', commonly known as the tanoak or tanbark-oak, is a broadleaf tree in the family Fagaceae, and the type species of the genus ''Notholithocarpus''. It is a hardwood tree that is native to the far western United Sta ...
(''Lithocarpus densiflorus''), Coast redwood and three Douglas fir trees, the latter tall. He found that the trees most exposed produced the most moisture and in five weeks of measurement (July 20–August 28, 1951) fog drip below the tanoak produced of moisture, more than the total annual precipitation on nearby
grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes such as clover, and other herbs. Grasslands occur ...
and
chaparral Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...
. The Douglas fir produced of fog drip and appeared to provide unique conditions supporting the orchids Giant helleborine (''Epipactis gigantea'') and Phantom orchid (''Cephalanthera austiniae''), since these plants were found exclusively in these moist ridge tops. * In the
Green Mountains The Green Mountains are a mountain range in the U.S. state of Vermont and are a subrange of the Appalachian Mountains. The range runs primarily south to north and extends approximately from the border with Massachusetts to the border with Que ...
of northern
Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...
at elevations above in the spruce–fir zone on the western slope of
Camel's Hump Camel's Hump (alternatively Camels Hump) is a mountain in the Green Mountains in the U.S. state of Vermont. The north slope of the mountain borders the Winooski River, which has carved through the Green Mountains over eons. At , it is tied wi ...
, fog drip increased the total moisture available up to 67% over rainfall alone. The authors concluded that the needlelike leaves and twiggy character of the conifers in the spruce–fir zone serve as effective mechanical collectors of the wind-driven cloud droplets.


Outside the United States

* One of the few areas in the world where people climb to the hilltops to get water in times of drought is the Downs in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
, where fog blows in from the
English Channel The English Channel, also known as the Channel, is an arm of the Atlantic Ocean that separates Southern England from northern France. It links to the southern part of the North Sea by the Strait of Dover at its northeastern end. It is the busi ...
to form what locals call " dew ponds", although they are formed by fog drip instead of dew. * Near the Pacific coast of
Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
and northern
Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
, in the nearly complete absence of any annual rainfall, fog drip allows vegetation, including trees, to grow in small areas called "
Lomas ''Lomas'' (Spanish for "hills"), also called fog oases and mist oases, are areas of fog-watered vegetation in the coastal desert of Peru and northern Chile. About 100 lomas near the Pacific Ocean are identified between 5°S and 30°S latitude, a ...
," which contrast with the surrounding areas of barren desert. * In the arid climate of northern
Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
, fog drip may be an important source of infiltration and
groundwater recharge Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in ...
, where isotopic analysis found the latter to be a mixture of rainwater and fog drip. * In the Pacific Ocean off Mexico, Cedros and
Guadalupe Island Guadalupe Island () is a volcanic island located off the western coast of Mexico's Baja California peninsula and about southwest of the city of Ensenada in the state of Baja California, in the Pacific Ocean. The various volcanoes are extinc ...
s support
Monterey pine ''Pinus radiata'' (synonym (taxonomy), syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast (California), Central Coast of California and Mexico (on Guadalupe Island and Ced ...
forests. Very sparse rainfall augmented by fog drip permits the existence of the forests.Oberbauer, Thomas A. (2013), "Floristic Analysis of Vegetation Communities on Isla de Cedros, Baja California, Mexico," https://www.academia.edu/1109025/Floristic_analysis_of_vegetation_communities_on_Isla_de_Cedros_Baja_California_Mexico, accessed 20 Jun 2018


See also

* Fog desert *
Cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...
*
Dew Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation. As the exposed surface cools by thermal radiation, radiating its heat, atmospheric moisture condenses at a rate grea ...


References


External links


FogQuest is a non-profit Canadian charity dedicated to helping developing countries harvest atmospheric water

Video: "Fog and Wind" - Cloud Forests of Santa Rosa Island, USGS Western Ecology Research Center
{{Webarchive, url=https://web.archive.org/web/20160304043621/http://gallery.usgs.gov/videos/594#.UIgbPWf_LnV , date=March 4, 2016
drip Drip, The Drip, or DRIP may refer to: * Drop (liquid) Biology and medicine * Intravenous therapy * Vitamin D receptor interacting protein (DRIP) * Mesomycetozoea, a class of eukaryotes (also known as ''DRIP clade'') * Murphy drip, in proctocl ...