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119-703: Water level in the river often fluctuates. The river is used for irrigation and is dammed by the Hassan II and Mohamed V Dams . Before French colonisation, the Moulouya River was considered as the border between Ottoman Algeria and the dynasties that controlled Morocco. A battle between the Ottomans and the Alawites took place in 1692 at the ford of this river. The Romans called this river Malva and Mulucha . In medieval British pseudo-history, it

238-540: A ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 275 to 900 kPa (40 to 130 psi) and flows of 3 to 76 L/s (50 to 1200 US gal/min), usually with nozzle diameters in the range of 10 to 50 mm (0.5 to 1.9 in). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging . Sprinklers can also be mounted on moving platforms connected to

357-419: A circular or semi-circular pattern. Traveling Sprinklers: These move along the hose path on their own, watering as they go, ideal for covering long, narrow spaces. Each type offers different advantages based on garden size and shape, water pressure, and specific watering needs. Subirrigation has been used for many years in field crops in areas with high water tables . It is a method of artificially raising

476-589: A clock or timer. Most automatic systems employ electric solenoid valves . Each zone has one or more of these valves that are wired to the controller. When the controller sends power to the valve, the valve opens, allowing water to flow to the sprinklers in that zone. There are two main types of sprinklers used in lawn irrigation, pop-up spray heads and rotors. Spray heads have a fixed spray pattern, while rotors have one or more streams that rotate. Spray heads are used to cover smaller areas, while rotors are used for larger areas. Golf course rotors are sometimes so large that

595-426: A computerized set of valves . In sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system using sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by

714-494: A direct financial cost to the farmer. Irrigation often requires pumping energy (either electricity or fossil fuel) to deliver water to the field or supply the correct operating pressure. Hence increased efficiency will reduce both the water cost and energy cost per unit of agricultural production. A reduction of water use on one field may mean that the farmer is able to irrigate a larger area of land, increasing total agricultural production. Low efficiency usually means that excess water

833-529: A field study published in 2021 by researchers at Stockholm University found that they are often transferred from water to air when waves reach land, are a significant source of air pollution , and eventually get into rain. The researchers concluded that pollution may impact large areas. In 2024, a worldwide study of 45,000 groundwater samples found that 31% of samples contained levels of PFAS that were harmful to human health; these samples were taken from areas not near any obvious source of contamination. Rain

952-416: A flood (spate), water is diverted to normally dry river beds (wadis) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions. Micro-irrigation , sometimes called localized irrigation , low volume irrigation , or trickle irrigation

1071-409: A higher profit than potatoes. The land is flood irrigated twice a day to simulate tidal flooding; the water is pumped from the sea using wind power. Additional benefits are soil remediation and carbon sequestration . Until the 1960s, there were fewer than half the number of people on the planet as of 2024. People were not as wealthy as today, consumed fewer calories and ate less meat , so less water

1190-483: A long duration. The final droplet size distribution is an exponential distribution . The number of droplets with diameter between d {\displaystyle d} and D + d D {\displaystyle D+dD} per unit volume of space is n ( d ) = n 0 e − d / ⟨ d ⟩ d D {\displaystyle n(d)=n_{0}e^{-d/\langle d\rangle }dD} . This

1309-460: A particular air temperature. How much water vapor a parcel of air can contain before it becomes saturated (100% relative humidity) and forms into a cloud (a group of visible tiny water or ice particles suspended above the Earth's surface) depends on its temperature. Warmer air can contain more water vapor than cooler air before becoming saturated. Therefore, one way to saturate a parcel of air

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1428-410: A physical barrier such as a mountain ( orographic lift ). Conductive cooling occurs when the air comes into contact with a colder surface, usually by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation , either by the air or by the surface underneath. Evaporative cooling occurs when moisture

1547-543: A point are estimated by using the value of reflectivity data at individual grid points. A radar equation is then used, which is Z = A R b , {\displaystyle Z=AR^{b},} where Z represents the radar reflectivity, R represents the rainfall rate, and A and b are constants. Satellite-derived rainfall estimates use passive microwave instruments aboard polar orbiting as well as geostationary weather satellites to indirectly measure rainfall rates. If one wants an accumulated rainfall over

1666-406: A rare rainfall event occurring on average once every 10 years. The rainfall will be greater and the flooding will be worse than the worst storm expected in any single year. A 100-year storm describes an extremely rare rainfall event occurring on average once in a century. The rainfall will be extreme and flooding worse than a 10-year event. The probability of an event in any year is the inverse of

1785-424: A rectangular or square pattern. They are good for covering large, flat areas evenly. Impact (or Pulsating) Sprinklers: These create a rotating, pulsating spray, which can cover a circular or semi-circular area. They are useful for watering large lawns. Stationary Sprinklers: These have a fixed spray pattern and are best for smaller areas or gardens. Rotary Sprinklers: These use spinning arms to distribute water in

1904-708: A result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme . The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting . Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution . Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage . In 2000,

2023-407: A result of this warming, monthly rainfall is about 28% greater between 32 and 64 km (20 and 40 mi) downwind of cities, compared with upwind. Some cities induce a total precipitation increase of 51%. Increasing temperatures tend to increase evaporation which can lead to more precipitation. Precipitation generally increased over land north of 30°N from 1900 through 2005 but has declined over

2142-424: A single sprinkler is combined with a valve and called a 'valve in head'. When used in a turf area, the sprinklers are installed with the top of the head flush with the ground surface. When the system is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more pressure in the lateral line, the sprinkler head will retract back into

2261-711: A small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising the water table to moisten the soil below the root zone of plants. Irrigation water can come from groundwater (extracted from springs or by using wells ), from surface water (withdrawn from rivers , lakes or reservoirs ) or from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . Irrigation can be supplementary to rainfall , which

2380-649: A teardrop. The biggest raindrops on Earth were recorded over Brazil and the Marshall Islands in 2004 — some of them were as large as 10 mm (0.39 in). The large size is explained by condensation on large smoke particles or by collisions between drops in small regions with particularly high content of liquid water. Raindrops associated with melting hail tend to be larger than other raindrops. Intensity and duration of rainfall are usually inversely related, i.e., high-intensity storms are likely to be of short duration and low-intensity storms can have

2499-425: A tendency to break up at larger sizes. Smaller drops are called cloud droplets, and their shape is spherical. As a raindrop increases in size, its shape becomes more oblate, with its largest cross-section facing the oncoming airflow. Large rain drops become increasingly flattened on the bottom, like hamburger buns; very large ones are shaped like parachutes . Contrary to popular belief, their shape does not resemble

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2618-470: A time period, one has to add up all the accumulations from each grid box within the images during that time. Rainfall intensity is classified according to the rate of precipitation, which depends on the considered time. The following categories are used to classify rainfall intensity: Terms used for a heavy or violent rain include gully washer, trash-mover and toad-strangler. The intensity can also be expressed by rainfall erosivity R-factor or in terms of

2737-399: Is supplementary to rainfall as happens in many parts of the world, or whether it is ' full irrigation' whereby crops rarely depend on any contribution from rainfall. Full irrigation is less common and only happens in arid landscapes experiencing very low rainfall or when crops are grown in semi-arid areas outside of any rainy seasons. Surface irrigation, also known as gravity irrigation, is

2856-472: Is a grassland biome located in semi-arid to semi-humid climate regions of subtropical and tropical latitudes , with rainfall between 750 and 1,270 mm (30 and 50 in) a year. They are widespread on Africa, and are also found in India, the northern parts of South America, Malaysia , and Australia. The humid subtropical climate zone is where winter rainfall is associated with large storms that

2975-480: Is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined and supported by trusses , mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are found and used in all parts of the world and allow irrigation of all types of terrain. Newer systems have drop sprinkler heads as shown in

3094-503: Is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Traditional drip irrigation use individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinklers, and mini-bubbler irrigation all belong to this category of irrigation methods. Drip irrigation, also known as microirrigation or trickle irrigation, functions as its name suggests. In this system, water

3213-511: Is a time when air quality improves, freshwater quality improves, and vegetation grows significantly. Tropical cyclones , a source of very heavy rainfall, consist of large air masses several hundred miles across with low pressure at the centre and with winds blowing inward towards the centre in either a clockwise direction (southern hemisphere) or counterclockwise (northern hemisphere). Although cyclones can take an enormous toll in lives and personal property, they may be important factors in

3332-654: Is accompanied by plentiful precipitation year-round. The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin , parts of western North America, parts of Western and South Australia , in southwestern South Africa and in parts of central Chile . The climate is characterized by hot, dry summers and cool, wet winters. A steppe is a dry grassland . Subarctic climates are cold with continuous permafrost and little precipitation. In 2022, levels of at least four perfluoroalkyl acids (PFAAs) in rain water worldwide greatly exceeded

3451-718: Is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature , or until it reaches saturation. The main ways water vapor is added to the air are wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet land, transpiration from plants, cool or dry air moving over warmer water, and lifting air over mountains. Water vapor normally begins to condense on condensation nuclei such as dust, ice, and salt in order to form clouds. Elevated portions of weather fronts (which are three-dimensional in nature) force broad areas of upward motion within

3570-563: Is also causing changes in the precipitation pattern, including wetter conditions across eastern North America and drier conditions in the tropics. Antarctica is the driest continent. The globally averaged annual precipitation over land is 715 mm (28.1 in), but over the whole Earth, it is much higher at 990 mm (39 in). Climate classification systems such as the Köppen classification system use average annual rainfall to help differentiate between differing climate regimes. Rainfall

3689-441: Is also employed to protect crops from frost , suppress weed growth in grain fields, and prevent soil consolidation . It is also used to cool livestock , reduce dust , dispose of sewage , and support mining operations. Drainage , which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation. There are several methods of irrigation that differ in how water

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3808-415: Is also the means of delivery of fertilizer. The process is known as fertigation . Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and labor-intensive. Lower water pressures are usually needed than for most other types of systems, with

3927-422: Is common in many parts of the world as rainfed agriculture , or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons. The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as

4046-842: Is commonly referred to as the Marshall–Palmer law after the researchers who first characterized it. The parameters are somewhat temperature-dependent, and the slope also scales with the rate of rainfall ⟨ d ⟩ − 1 = 41 R − 0.21 {\displaystyle \langle d\rangle ^{-1}=41R^{-0.21}} (d in centimeters and R in millimeters per hour). Deviations can occur for small droplets and during different rainfall conditions. The distribution tends to fit averaged rainfall, while instantaneous size spectra often deviate and have been modeled as gamma distributions . The distribution has an upper limit due to droplet fragmentation. Raindrops impact at their terminal velocity , which

4165-422: Is delivered at or near the root zone of plants, one drop at a time. This method can be the most water-efficient method of irrigation, if managed properly; evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90% when managed correctly. In modern agriculture, drip irrigation is often combined with plastic mulch , further reducing evaporation, and

4284-457: Is dependent upon farmers having sufficient access to water. However, water scarcity is already a critical constraint to farming in many parts of the world. There are several methods of irrigation. They vary in how the water is supplied to the plants. The goal is to apply the water to the plants as uniformly as possible, so that each plant has the amount of water it needs, neither too much nor too little. Irrigation can also be understood whether it

4403-410: Is derived from natural sources such as volcanoes, and wetlands (sulfate-reducing bacteria); and anthropogenic sources such as the combustion of fossil fuels , and mining where H 2 S is present. Nitric acid is produced by natural sources such as lightning, soil bacteria, and natural fires; while also produced anthropogenically by the combustion of fossil fuels and from power plants. In the past 20 years,

4522-487: Is equally distributed through the year. Some areas with pronounced rainy seasons will see a break in rainfall mid-season when the Intertropical Convergence Zone or monsoon trough move poleward of their location during the middle of the warm season. When the wet season occurs during the warm season, or summer , rain falls mainly during the late afternoon and early evening hours. The wet season

4641-498: Is greater for larger drops due to their larger mass-to-drag ratio. At sea level and without wind, 0.5 mm (0.020 in) drizzle impacts at 2 m/s (6.6 ft/s) or 7.2 km/h (4.5 mph), while large 5 mm (0.20 in) drops impact at around 9 m/s (30 ft/s) or 32 km/h (20 mph). Rain falling on loosely packed material such as newly fallen ash can produce dimples that can be fossilized, called raindrop impressions . The air density dependence of

4760-424: Is less expensive to install than a center pivot, but much more labor-intensive to operate – it does not travel automatically across the field: it applies water in a stationary strip, must be drained, and then rolled to a new strip. Most systems use 100 or 130 mm (4 or 5 inch) diameter aluminum pipe. The pipe doubles both as water transport and as an axle for rotating all the wheels. A drive system (often found near

4879-449: Is lost through seepage or runoff, both of which can result in loss of crop nutrients or pesticides with potential adverse impacts on the surrounding environment. Rain Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity . Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on

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4998-497: Is measured in units of length per unit time, typically in millimeters per hour, or in countries where imperial units are more common, inches per hour. The "length", or more accurately, "depth" being measured is the depth of rain water that would accumulate on a flat, horizontal and impermeable surface during a given amount of time, typically an hour. One millimeter of rainfall is the equivalent of one liter of water per square meter. The standard way of measuring rainfall or snowfall

5117-408: Is measured using rain gauges . Rainfall amounts can be estimated by weather radar . Air contains water vapor, and the amount of water in a given mass of dry air, known as the mixing ratio , is measured in grams of water per kilogram of dry air (g/kg). The amount of moisture in the air is also commonly reported as relative humidity ; which is the percentage of the total water vapor air can hold at

5236-421: Is often no alternative for farmers but to use water polluted with urban waste directly to water their crops. There can be significant health hazards related to using untreated wastewater in agriculture. Municipal wastewater can contain a mixture of chemical and biological pollutants. In low-income countries, there are often high levels of pathogens from excreta. In emerging nations , where industrial development

5355-443: Is often the irrigation choice for developing nations, for low value crops and for large fields. Where water levels from the irrigation source permit, the levels are controlled by dikes ( levees ), usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to

5474-422: Is outpacing environmental regulation, there are increasing risks from inorganic and organic chemicals. The World Health Organization developed guidelines for safe use of wastewater in 2006, advocating a ‘multiple-barrier' approach wastewater use, for example by encouraging farmers to adopt various risk-reducing behaviors. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in

5593-597: Is possible where upslope flow is maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the air mass . The movement of the monsoon trough , or Intertropical Convergence Zone , brings rainy seasons to savannah climes . The urban heat island effect leads to increased rainfall, both in amounts and intensity, downwind of cities. Global warming

5712-586: Is practiced in the vineyards at Lanzarote using stones to condense water. Fog collectors are also made of canvas or foil sheets. Using condensate from air conditioning units as a water source is also becoming more popular in large urban areas. As of November 2019 a Glasgow-based startup has helped a farmer in Scotland to establish edible saltmarsh crops irrigated with sea water. An acre of previously marginal land has been put under cultivation to grow samphire , sea blite , and sea aster ; these plants yield

5831-424: Is referred to as banded structure. Rainbands in advance of warm occluded fronts and warm fronts are associated with weak upward motion, and tend to be wide and stratiform in nature. Rainbands spawned near and ahead of cold fronts can be squall lines which are able to produce tornadoes . Rainbands associated with cold fronts can be warped by mountain barriers perpendicular to the front's orientation due to

5950-478: Is similar in principle and action to subsurface basin irrigation. Another type of subirrigation is the self-watering container, also known as a sub-irrigated planter . This consists of a planter suspended over a reservoir with some type of wicking material such as a polyester rope. The water is drawn up the wick through capillary action. A similar technique is the wicking bed ; this too uses capillary action. Modern irrigation methods are efficient enough to supply

6069-437: Is supplied at one end using a large hose. After sufficient irrigation has been applied to one strip of the field, the hose is removed, the water drained from the system, and the assembly rolled either by hand or with a purpose-built mechanism, so that the sprinklers are moved to a different position across the field. The hose is reconnected. The process is repeated in a pattern until the whole field has been irrigated. This system

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6188-419: Is supplied to plants. Surface irrigation , also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation , water is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as

6307-561: Is the expected amount of liquid precipitation accumulated over a specified time period over a specified area. A QPF will be specified when a measurable precipitation type reaching a minimum threshold is forecast for any hour during a QPF valid period. Precipitation forecasts tend to be bound by synoptic hours such as 0000, 0600, 1200 and 1800  GMT . Terrain is considered in QPFs by use of topography or based upon climatological precipitation patterns from observations with fine detail. Starting in

6426-432: Is the practice of applying controlled amounts of water to land to help grow crops , landscape plants , and lawns . Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation

6545-411: Is the presence of a thick layer of air aloft which is above the melting point of water, which melts the frozen precipitation well before it reaches the ground. If there is a shallow near-surface layer that is below freezing, freezing rain (rain which freezes on contact with surfaces in subfreezing environments) will result. Hail becomes an increasingly infrequent occurrence when the freezing level within

6664-440: Is the standard rain gauge, which can be found in 100-mm (4-in) plastic and 200-mm (8-in) metal varieties. The inner cylinder is filled by 25 mm (0.98 in) of rain, with overflow flowing into the outer cylinder. Plastic gauges have markings on the inner cylinder down to 0.25 mm (0.0098 in) resolution, while metal gauges require use of a stick designed with the appropriate 0.25 mm (0.0098 in) markings. After

6783-399: Is to cool it. The dew point is the temperature to which a parcel must be cooled in order to become saturated. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling, and evaporative cooling. Adiabatic cooling occurs when air rises and expands. The air can rise due to convection , large-scale atmospheric motions, or

6902-583: Is used for irrigation in agriculture, the nutrient (nitrogen and phosphorus) content of the treated wastewater has the benefit of acting as a fertilizer . This can make the reuse of excreta contained in sewage attractive. In developing countries , agriculture is increasingly using untreated municipal wastewater for irrigation – often in an unsafe manner. Cities provide lucrative markets for fresh produce, so they are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users, there

7021-556: Is usually not considered as a form of irrigation. Rainwater harvesting is the collection of runoff water from roofs or unused land and the concentration of this. Irrigation with recycled municipal wastewater can also serve to fertilize plants if it contains nutrients, such as nitrogen, phosphorus and potassium. There are benefits of using recycled water for irrigation, including the lower cost compared to some other sources and consistency of supply regardless of season, climatic conditions and associated water restrictions. When reclaimed water

7140-589: The Great Basin and Mojave Deserts . The wet, or rainy, season is the time of year, covering one or more months, when most of the average annual rainfall in a region falls. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the tropics and subtropics . Savanna climates and areas with monsoon regimes have wet summers and dry winters. Tropical rainforests technically do not have dry or wet seasons, since their rainfall

7259-577: The United States , China , and European countries like the United Kingdom , also fund and organize some schemes within other nations. By 2021 the global land area equipped for irrigation reached 352 million ha, an increase of 22% from the 289 million ha of 2000 and more than twice the 1960s land area equipped for irrigation. The vast majority is located in Asia (70%), where irrigation

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7378-573: The commercial greenhouse production, usually for potted plants . Water is delivered from below, absorbed by upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10–20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor savings through reduced system maintenance and automation . It

7497-409: The tropics appears to be convective; however, it has been suggested that stratiform precipitation also occurs. Graupel and hail indicate convection. In mid-latitudes, convective precipitation is intermittent and often associated with baroclinic boundaries such as cold fronts , squall lines , and warm fronts. Orographic precipitation occurs on the windward side of mountains and is caused by

7616-455: The westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones. Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees away from the equator. An oceanic (or maritime) climate is typically found along the west coasts at the middle latitudes of all the world's continents, bordering cool oceans, as well as southeastern Australia, and

7735-461: The EPA's lifetime drinking water health advisories as well as comparable Danish, Dutch, and European Union safety standards, leading to the conclusion that "the global spread of these four PFAAs in the atmosphere has led to the planetary boundary for chemical pollution being exceeded". It had been thought that PFAAs would eventually end up in the oceans, where they would be diluted over decades, but

7854-404: The Earth's atmosphere which form clouds decks such as altostratus or cirrostratus . Stratus is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can also form due to the lifting of advection fog during breezy conditions. Coalescence occurs when water droplets fuse to create larger water droplets. Air resistance typically causes

7973-553: The Earth. It provides water for hydroelectric power plants , crop irrigation , and suitable conditions for many types of ecosystems . The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts . If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands . In mountainous areas, heavy precipitation

8092-678: The Internet, such as CoCoRAHS or GLOBE. If a network is not available in the area where one lives, the nearest local weather or met office will likely be interested in the measurement. One of the main uses of weather radar is to be able to assess the amount of precipitations fallen over large basins for hydrological purposes. For instance, river flood control , sewer management and dam construction are all areas where planners use rainfall accumulation data. Radar-derived rainfall estimates complement surface station data which can be used for calibration. To produce radar accumulations, rain rates over

8211-760: The Nile river in Egypt and Sudan; and in the Mississippi-Missouri river basin, the Southern Great Plains, and in parts of California in the United States. Smaller irrigation areas are spread across almost all populated parts of the world. By 2012, the area of irrigated land had increased to an estimated total of 3,242,917 km (801 million acres), which is nearly the size of India. The irrigation of 20% of farming land accounts for

8330-889: The Northeast and Midwest, which in the past decade, have seen 31 and 16 percent more heavy downpours compared to the 1950s. Rhode Island is the state with the largest increase, 104%. McAllen, Texas is the city with the largest increase, 700%. Heavy downpour in the analysis are the days where total precipitation exceeded the top one percent of all rain and snow days during the years 1950–2014. The most successful attempts at influencing weather involve cloud seeding , which include techniques used to increase winter precipitation over mountains and suppress hail . Rainbands are cloud and precipitation areas which are significantly elongated. Rainbands can be stratiform or convective , and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation

8449-405: The atmosphere exceeds 3,400 m (11,000 ft) above ground level. Convective rain , or showery precipitation, occurs from convective clouds (e.g., cumulonimbus or cumulus congestus ). It falls as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a relatively short time, as convective clouds have limited horizontal extent. Most precipitation in

8568-469: The center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water-powered. These were replaced by hydraulic systems ( T-L Irrigation ) and electric-motor-driven systems (Reinke, Valley, Zimmatic). Many modern pivots feature GPS devices. A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint, and sprinklers along its length, are coupled together. Water

8687-485: The centre of the wheel line) rotates the clamped-together pipe sections as a single axle, rolling the whole wheel line. Manual adjustment of individual wheel positions may be necessary if the system becomes misaligned. Wheel line systems are limited in the amount of water they can carry, and limited in the height of crops that can be irrigated. One useful feature of a lateral move system is that it consists of sections that can be easily disconnected, adapting to field shape as

8806-711: The components of these irrigation systems are hidden under ground, since aesthetics are important in a landscape. A typical lawn sprinkler system will consist of one or more zones, limited in size by the capacity of the water source. Each zone will cover a designated portion of the landscape. Sections of the landscape will usually be divided by microclimate , type of plant material, and type of irrigation equipment. A landscape irrigation system may also include zones containing drip irrigation, bubblers, or other types of equipment besides sprinklers. Although manual systems are still used, most lawn sprinkler systems may be operated automatically using an irrigation controller , sometimes called

8925-517: The concentrations of nitric and sulfuric acid has decreased in presence of rainwater, which may be due to the significant increase in ammonium (most likely as ammonia from livestock production), which acts as a buffer in acid rain and raises the pH. The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Specifically,

9044-612: The contiguous United States, total annual precipitation increased at an average rate of 6.1 percent since 1900, with the greatest increases within the East North Central climate region (11.6 percent per century) and the South (11.1 percent). Hawaii was the only region to show a decrease (−9.25 percent). Analysis of 65 years of United States of America rainfall records show the lower 48 states have an increase in heavy downpours since 1950. The largest increases are in

9163-647: The course of the week, the likelihood of rain increases: it peaks by Saturday, after five days of weekday pollution has been built up. In heavily populated areas that are near the coast, such as the United States' Eastern Seaboard , the effect can be dramatic: there is a 22% higher chance of rain on Saturdays than on Mondays. The urban heat island effect warms cities 0.6 to 5.6 °C (33.1 to 42.1 °F) above surrounding suburbs and rural areas. This extra heat leads to greater upward motion, which can induce additional shower and thunderstorm activity. Rainfall rates downwind of cities are increased between 48% and 116%. Partly as

9282-408: The crop or field requirements. Increasing the application efficiency means that the amount of crop produced per unit of water increases. Improved efficiency may either be achieved by applying less water to an existing field or by using water more wisely thereby achieving higher yields in the same area of land. In some parts of the world, farmers are charged for irrigation water hence over-application has

9401-412: The crystal and neighboring water droplets. This process is temperature dependent, as supercooled water droplets only exist in a cloud that is below freezing. In addition, because of the great temperature difference between cloud and ground level, these ice crystals may melt as they fall and become rain. Raindrops have sizes ranging from 0.1 to 9 mm (0.0039 to 0.3543 in) mean diameter but develop

9520-559: The descending and generally warming, leeward side where a rain shadow is observed. In Hawaii , Mount Waiʻaleʻale , on the island of Kauai, is notable for its extreme rainfall, as it is amongst the places in the world with the highest levels of rainfall, with 9,500 mm (373 in). Systems known as Kona storms affect the state with heavy rains between October and April. Local climates vary considerably on each island due to their topography, divisible into windward ( Koʻolau ) and leeward ( Kona ) regions based upon location relative to

9639-410: The entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little. Water use efficiency in the field can be determined as follows: Increased irrigation efficiency has a number of positive outcomes for the farmer, the community and the wider environment. Low application efficiency infers that the amount of water applied to the field is in excess of

9758-502: The exception of low-energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from

9877-511: The formation of a low-level barrier jet . Bands of thunderstorms can form with sea breeze and land breeze boundaries if enough moisture is present. If sea breeze rainbands become active enough just ahead of a cold front, they can mask the location of the cold front itself. Once a cyclone occludes an occluded front (a trough of warm air aloft) will be caused by strong southerly winds on its eastern periphery rotating aloft around its northeast, and ultimately northwestern, periphery (also termed

9996-482: The front is unstable enough for convection. Banding within the comma head precipitation pattern of an extratropical cyclone can yield significant amounts of rain. Behind extratropical cyclones during fall and winter, rainbands can form downwind of relative warm bodies of water such as the Great Lakes . Downwind of islands, bands of showers and thunderstorms can develop due to low-level wind convergence downwind of

10115-534: The ground. In flower beds or shrub areas, sprinklers may be mounted on above ground risers or even taller pop-up sprinklers may be used and installed flush as in a lawn area. Hose-end sprinklers are devices attached to the end of a garden hose, used for watering lawns, gardens, or plants. They come in a variety of designs and styles, allowing you to adjust the water flow, pattern, and range for efficient irrigation. Some common types of hose-end sprinklers include: Oscillating Sprinklers: These spray water back and forth in

10234-400: The ground. This is termed virga and is more often seen in hot and dry climates. Stratiform (a broad shield of precipitation with a relatively similar intensity) and dynamic precipitation (convective precipitation which is showery in nature with large changes in intensity over short distances) occur as a consequence of slow ascent of air in synoptic systems (on the order of cm/s), such as in

10353-552: The higher mountains. Windward sides face the east to northeast trade winds and receive much more rainfall; leeward sides are drier and sunnier, with less rain and less cloud cover. In South America, the Andes mountain range blocks Pacific moisture that arrives in that continent, resulting in a desert-like climate just downwind across western Argentina. The Sierra Nevada range creates the same effect in North America forming

10472-409: The image that follows. As of 2017 most center pivot systems have drops hanging from a U-shaped pipe attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. Crops are often planted in a circle to conform to

10591-438: The inner cylinder is filled, the amount inside it is discarded, then filled with the remaining rainfall in the outer cylinder until all the fluid in the outer cylinder is gone, adding to the overall total until the outer cylinder is empty. Other types of gauges include the popular wedge gauge (the cheapest rain gauge and most fragile), the tipping bucket rain gauge, and the weighing rain gauge. For those looking to measure rainfall

10710-490: The irrigation results in flooding or near flooding of the cultivated land. Historically, surface irrigation is the most common method of irrigating agricultural land across most parts of the world. The water application efficiency of surface irrigation is typically lower than other forms of irrigation, due in part to the lack of control of applied depths. Surface irrigation involves a significantly lower capital cost and energy requirement than pressurised irrigation systems. Hence it

10829-422: The island edges. Offshore California , this has been noted in the wake of cold fronts. Rainbands within tropical cyclones are curved in orientation. Tropical cyclone rainbands contain showers and thunderstorms that, together with the eyewall and the eye, constitute a hurricane or tropical storm . The extent of rainbands around a tropical cyclone can help determine the cyclone's intensity. The phrase acid rain

10948-399: The level of the land. Surface irrigation is even used to water urban gardens in certain areas, for example, in and around Phoenix, Arizona . The irrigated area is surrounded by a berm and the water is delivered according to a schedule set by a local irrigation district . A special form of irrigation using surface water is spate irrigation , also called floodwater harvesting. In case of

11067-441: The line is moved. They are most often used for small, rectilinear, or oddly-shaped fields, hilly or mountainous regions, or in regions where labor is inexpensive. A lawn sprinkler system is permanently installed, as opposed to a hose-end sprinkler, which is portable. Sprinkler systems are installed in residential lawns, in commercial landscapes, for churches and schools, in public parks and cemeteries, and on golf courses . Most of

11186-427: The maximum raindrop diameter together with fossil raindrop imprints has been used to constrain the density of the air 2.7 billion years ago. The sound of raindrops hitting water is caused by bubbles of air oscillating underwater . The METAR code for rain is RA, while the coding for rain showers is SHRA. In certain conditions, precipitation may fall from a cloud but then evaporate or sublime before reaching

11305-428: The most inexpensively, a can that is cylindrical with straight sides will act as a rain gauge if left out in the open, but its accuracy will depend on what ruler is used to measure the rain with. Any of the above rain gauges can be made at home, with enough know-how. When a precipitation measurement is made, various networks exist across the United States and elsewhere where rainfall measurements can be submitted through

11424-462: The number of heavy precipitation events over many areas during the past century, as well as an increase since the 1970s in the prevalence of droughts—especially in the tropics and subtropics. Changes in precipitation and evaporation over the oceans are suggested by the decreased salinity of mid- and high-latitude waters (implying more precipitation), along with increased salinity in lower latitudes (implying less precipitation and/or more evaporation). Over

11543-435: The oldest form of irrigation and has been in use for thousands of years. In surface ( furrow, flood , or level basin ) irrigation systems, water moves across the surface of agricultural lands, in order to wet it and infiltrate into the soil. Water moves by following gravity or the slope of the land. Surface irrigation can be subdivided into furrow, border strip or basin irrigation . It is often called flood irrigation when

11662-436: The overarching goal of increasing self-sufficiency. Irrigation water can come from groundwater (extracted from springs or by using wells ), from surface water (withdrawn from rivers , lakes or reservoirs ) or from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting

11781-478: The precipitation regimes of places they impact, as they may bring much-needed precipitation to otherwise dry regions. Areas in their path can receive a year's worth of rainfall from a tropical cyclone passage. The fine particulate matter produced by car exhaust and other human sources of pollution forms cloud condensation nuclei leads to the production of clouds and increases the likelihood of rain. As commuters and commercial traffic cause pollution to build up over

11900-579: The primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest , monsoon , tropical savanna , humid subtropical , humid continental , oceanic climate , Mediterranean climate , steppe , subarctic climate , tundra , polar ice cap , and desert . Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 and 2,000 mm (69 and 79 in). A tropical savanna

12019-567: The production of 40% of food production. The scale of irrigation increased dramatically over the 20th century. In 1800, 8 million hectares globally were irrigated, in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe includes canals redirecting surface water, groundwater pumping, and diverting water from dams. National governments lead most irrigation schemes within their borders, but private investors and other nations, especially

12138-399: The rainfall time-structure n-index . The average time between occurrences of an event with a specified intensity and duration is called the return period . The intensity of a storm can be predicted for any return period and storm duration, from charts based on historic data for the location. The return period is often expressed as an n -year event. For instance, a 10-year storm describes

12257-475: The regions saw increases in the area equipped for irrigation, with Africa growing the fastest (+29%), followed by Asia (+25%), Oceania (+24%), the Americas (+19%) and Europe (+2%). Irrigation enables the production of more crops, especially commodity crops in areas which otherwise could not support them. Countries frequently invested in irrigation to increase wheat , rice , or cotton production, often with

12376-428: The return period (assuming the probability remains the same for each year). For instance, a 10-year storm has a probability of occurring of 10 percent in any given year, and a 100-year storm occurs with a 1 percent probability in a year. As with all probability events, it is possible, though improbable, to have multiple 100-year storms in a single year. The Quantitative Precipitation Forecast (abbreviated QPF)

12495-442: The rising air motion of a large-scale flow of moist air across the mountain ridge, resulting in adiabatic cooling and condensation. In mountainous parts of the world subjected to relatively consistent winds (for example, the trade winds ), a more moist climate usually prevails on the windward side of a mountain than on the leeward or downwind side. Moisture is removed by orographic lift, leaving drier air (see katabatic wind ) on

12614-528: The river also formed the eastern border of the Spanish Protectorate of Morocco . In August 2011 fish were killed by pollutants in the Moulouya River and local residents feared for their crops and livestock. This article related to a river in Morocco is a stub . You can help Misplaced Pages by expanding it . Irrigation Irrigation (also referred to as watering of plants )

12733-400: The sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water. Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable. Center pivot irrigation

12852-493: The sunlight; applying water carefully so it does not contaminate leaves likely to be eaten raw; cleaning vegetables with disinfectant; or allowing fecal sludge used in farming to dry before being used as a human manure. Irrigation water can also come from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . In countries where humid air sweeps through at night, water can be obtained by condensation onto cold surfaces. This

12971-812: The total fertile land was 2,788,000 km (689 million acres) and it was equipped with irrigation infrastructure worldwide. About 68% of this area is in Asia, 17% in the Americas, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found in Northern and Eastern India and Pakistan along the Ganges and Indus rivers; in the Hai He, Huang He and Yangtze basins in China; along

13090-492: The tropics since the 1970s. Globally there has been no statistically significant overall trend in precipitation over the past century, although trends have varied widely by region and over time. Eastern portions of North and South America, northern Europe, and northern and central Asia have become wetter. The Sahel, the Mediterranean, southern Africa and parts of southern Asia have become drier. There has been an increase in

13209-543: The vicinity of cold fronts and near and poleward of surface warm fronts . Similar ascent is seen around tropical cyclones outside the eyewall , and in comma-head precipitation patterns around mid-latitude cyclones . A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually, their passage is associated with a drying of the air mass. Occluded fronts usually form around mature low-pressure areas. What separates rainfall from other precipitation types, such as ice pellets and snow,

13328-408: The warm conveyor belt), forcing a surface trough to continue into the cold sector on a similar curve to the occluded front. The front creates the portion of an occluded cyclone known as its comma head , due to the comma -like shape of the mid-tropospheric cloudiness that accompanies the feature. It can also be the focus of locally heavy precipitation, with thunderstorms possible if the atmosphere along

13447-555: The water droplets in a cloud to remain stationary. When air turbulence occurs, water droplets collide, producing larger droplets. As these larger water droplets descend, coalescence continues, so that drops become heavy enough to overcome air resistance and fall as rain. Coalescence generally happens most often in clouds above freezing (in their top) and is also known as the warm rain process. In clouds below freezing, when ice crystals gain enough mass they begin to fall. This generally requires more mass than coalescence when occurring between

13566-405: The water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these use a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When

13685-414: The water table to allow the soil to be moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and thereby control the water table. Subirrigation is also used in

13804-413: Was a key component of the green revolution; the Americas account for 16% and Europe for 8% of the world total. India (76 million ha) and China (75 million ha) have the largest equipped area for irrigation, far ahead of the United States o fAmerica (27 million ha). China and India also have the largest net gains in equipped area between 2000 and 2020 (+21 million ha for China and +15 million ha for India). All

13923-558: Was first used by Scottish chemist Robert Augus Smith in 1852. The pH of rain varies, especially due to its origin. On America's East Coast, rain that is derived from the Atlantic Ocean typically has a pH of 5.0–5.6; rain that comes across the continental from the west has a pH of 3.8–4.8; and local thunderstorms can have a pH as low as 2.0. Rain becomes acidic primarily due to the presence of two strong acids, sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ). Sulfuric acid

14042-601: Was mentioned as a location along the route supposedly travelled by the ancestors of the Scotti , and by Brutus of Troy . The Moulouya River formed the eastern border of the kingdom of Mauretania since King Bocchus I , and more recently of the Rif Republic in the 1920s, a small part of Morocco containing important cities like Saïdia and Oujda lying to the east, between the Moulouya and the border with Algeria. Until 1956

14161-666: Was needed to produce their food. They required a third of the volume of water humans presently take from rivers. Today, the competition for water resources is much more intense, because there are now more than seven billion people on the planet, increasing the likelihood of overconsumption of food produced by water-thirsty animal agriculture and intensive farming practices. This creates increasing competition for water from industry , urbanisation and biofuel crops . Farmers will have to strive to increase productivity to meet growing demands for food , while industry and cities find ways to use water more efficiently. Successful agriculture

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