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108-525: Khuttal , frequently also in the plural form Khuttalan (and variants such as Khutlan , Khatlan , in Chinese sources K'o-tut-lo ) was a medieval region and principality on the north bank of the river Oxus (modern Amu Darya ), lying between its tributaries Vakhsh and Panj . It corresponds roughly to the modern Khatlon Province of Tajikistan . The pre-Islamic Principality of Khuttal played an active role, sometimes as an ally, sometimes as an enemy, of

216-643: A $ 720 million four-year investment deal with the Taliban government of Afghanistan for extraction on its side of the Amu Darya basin. The deal will see a 15% royalty given to the Afghan government over the course of its 25-year term. The Chinese see this basin as the third-largest potential gas field in the world. The clashing noise of battle reached the sky The blood of the Bengalees flowed like

324-499: A channel around 11 micron wavelength and primarily give information about cloud tops. Due to the typical structure of the atmosphere, cloud-top temperatures are approximately inversely related to cloud-top heights, meaning colder clouds almost always occur at higher altitudes. Further, cloud tops with a lot of small-scale variation are likely to be more vigorous than smooth-topped clouds. Various mathematical schemes, or algorithms, use these and other properties to estimate precipitation from

432-489: A clear derivative of Vakhsh , the name of the largest tributary of the river. In Sanskrit texts , the river is also referred to as Vakṣu ( वक्षु ). The Brahmanda Purana refers to the river as Chaksu which means 'an eye'. The Avestan texts too refer to the river as Yakhsha/Vakhsha (and Yakhsha Arta ('Upper Yakhsha'), referring to the Jaxartes / Syr Darya twin river to Amu Darya). In Middle Persian sources of

540-450: A cloud. Short, intense periods of rain in scattered locations are called showers . Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed by the low temperature into clouds and rain. This process is typically active when freezing rain occurs. A stationary front is often present near the area of freezing rain and serves as the focus for forcing moist air to rise. Provided there

648-405: A concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones . Lake-effect snowfall can be locally heavy. Thundersnow is possible within a cyclone's comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On

756-705: A dramatic effect on agriculture. All plants need at least some water to survive, therefore rain (being the most effective means of watering) is important to agriculture. While a regular rain pattern is usually vital to healthy plants, too much or too little rainfall can be harmful, even devastating to crops. Drought can kill crops and increase erosion, while overly wet weather can cause harmful fungus growth. Plants need varying amounts of rainfall to survive. For example, certain cacti require small amounts of water, while tropical plants may need up to hundreds of inches of rain per year to survive. In areas with wet and dry seasons, soil nutrients diminish and erosion increases during

864-425: A layer of above-freezing air exists with sub-freezing air both above and below. This causes the partial or complete melting of any snowflakes falling through the warm layer. As they fall back into the sub-freezing layer closer to the surface, they re-freeze into ice pellets. However, if the sub-freezing layer beneath the warm layer is too small, the precipitation will not have time to re-freeze, and freezing rain will be

972-468: A league The shorn and parcelled Oxus strains along Through beds of sand and matted rushy isles — Oxus, forgetting the bright speed he had In his high mountain-cradle in Pamere , A foiled circuitous wanderer: — till at last The longed-for dash of waves is heard, and wide His luminous home of waters opens, bright And tranquil, from whose floor the new-bathed stars Emerge, and shine upon

1080-411: 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

1188-567: A single year. A significant portion of the annual precipitation in any particular place (no weather station in Africa or South America were considered) falls on only a few days, typically about 50% during the 12 days with the most precipitation. 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,

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1296-409: A slow-falling drizzle , which has been observed as Rain puddles at its equator and polar regions. Precipitation is a major component of the water cycle , and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 km (121,000 cu mi) of water falls as precipitation each year, 398,000 km (95,000 cu mi) of it over the oceans. Given

1404-752: A subject of research. Although the ice is clear, scattering of light by the crystal facets and hollows/imperfections mean that the crystals often appear white in color due to diffuse reflection of the whole spectrum of light by the small ice particles. The shape of the snowflake is determined broadly by the temperature and humidity at which it is formed. Rarely, at a temperature of around −2 °C (28 °F), snowflakes can form in threefold symmetry—triangular snowflakes. The most common snow particles are visibly irregular, although near-perfect snowflakes may be more common in pictures because they are more visually appealing. No two snowflakes are alike, as they grow at different rates and in different patterns depending on

1512-407: A variety of datasets possessing different formats, time/space grids, periods of record and regions of coverage, input datasets, and analysis procedures, as well as many different forms of dataset version designators. In many cases, one of the modern multi-satellite data sets is the best choice for general use. The likelihood or probability of an event with a specified intensity and duration is called

1620-420: Is IC. Occult deposition occurs when mist or air that is highly saturated with water vapour interacts with the leaves of trees or shrubs it passes over. Stratiform or dynamic precipitation occurs as a consequence of slow ascent of air in synoptic systems (on the order of cm/s), such as over surface cold fronts , and over and ahead of warm fronts . Similar ascent is seen around tropical cyclones outside of

1728-410: Is RA, while the coding for rain showers is SHRA. Ice pellets or sleet are a form of precipitation consisting of small, translucent balls of ice. Ice pellets are usually (but not always) smaller than hailstones. They often bounce when they hit the ground, and generally do not freeze into a solid mass unless mixed with freezing rain . The METAR code for ice pellets is PL . Ice pellets form when

1836-482: 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 (and sometimes snowfall) is associated with large storms that

1944-480: 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. 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

2052-449: Is a time when air quality improves, freshwater quality improves, and vegetation grows significantly. Soil nutrients diminish and erosion increases. Animals have adaptation and survival strategies for the wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before

2160-582: 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 southern 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. Precipitation, especially rain, has

2268-620: 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. Coalescence occurs when water droplets fuse to create larger water droplets, or when water droplets freeze onto an ice crystal, which

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2376-437: Is associated with their warm front is often extensive, forced by weak upward vertical motion of air over the frontal boundary which condenses as it cools and produces precipitation within an elongated band, which is wide and stratiform , meaning falling out of nimbostratus clouds. When moist air tries to dislodge an arctic air mass, overrunning snow can result within the poleward side of the elongated precipitation band . In

2484-526: Is derived from Gihon , the biblical name for one of the four rivers of the Garden of Eden . The Amu Darya passes through one of the world's highest deserts. Western travelers in the 19th century mentioned that one of the names by which the river was known in Afghanistan was Gozan , and that this name was used by Greek, Mongol, Chinese, Persian, Jewish, and Afghan historians. However, this name

2592-487: 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

2700-416: Is filled by 2.5 cm (0.98 in) of rain, with overflow flowing into the outer cylinder. Plastic gauges have markings on the inner cylinder down to 1 ⁄ 4  mm (0.0098 in) resolution, while metal gauges require use of a stick designed with the appropriate 1 ⁄ 4  mm (0.0098 in) markings. After the inner cylinder is filled, the amount inside is discarded, then filled with

2808-401: Is intermittent and often associated with baroclinic boundaries such as cold fronts , squall lines , and warm fronts. Convective precipitation mostly consist of mesoscale convective systems and they produce torrential rainfalls with thunderstorms, wind damages, and other forms of severe weather events. Orographic precipitation occurs on the windward (upwind) side of mountains and is caused by

2916-759: Is known as the Bergeron process . The fall rate of very small droplets is negligible, hence clouds do not fall out of the sky; precipitation will only occur when these coalesce into larger drops. droplets with different size will have different terminal velocity that cause droplets collision and producing larger droplets, Turbulence will enhance the collision process. As these larger water droplets descend, coalescence continues, so that drops become heavy enough to overcome air resistance and fall as rain. Raindrops have sizes ranging from 5.1 to 20 millimetres (0.20 to 0.79 in) mean diameter, above which they tend to break up. Smaller drops are called cloud droplets, and their shape

3024-540: Is made, various networks exist across the United States and elsewhere where rainfall measurements can be submitted through the Internet, such as CoCoRAHS or GLOBE . If a network is not available in the area where one lives, the nearest local weather office will likely be interested in the measurement. A concept used in precipitation measurement is the hydrometeor. Any particulates of liquid or solid water in

3132-539: Is necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely nimbostratus and cumulonimbus if significant precipitation is involved. Eventually, the cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where relatively warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes

3240-579: Is no longer used. The river's total length is 2,400 kilometres (1,500 mi) and its drainage basin totals 534,739 square kilometres (206,464 sq mi) in area, providing a mean discharge of around 97.4 cubic kilometres (23.4 cu mi) of water per year. The river is navigable for over 1,450 kilometres (900 mi). All of the water comes from the high mountains in the south where annual precipitation can be over 1,000 mm (39 in). Even before large-scale irrigation began, high summer evaporation meant that not all of this discharge reached

3348-519: Is spherical. As a raindrop increases in size, its shape becomes more oblate , with its largest cross-section facing the oncoming airflow. Contrary to the cartoon pictures of raindrops, their shape does not resemble a teardrop. 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 a long duration. Rain drops associated with melting hail tend to be larger than other rain drops. The METAR code for rain

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3456-489: Is the temperature to which a parcel of air must be cooled in order to become saturated, and (unless super-saturation occurs) condenses to water. Water vapor normally begins to condense on condensation nuclei such as dust, ice, and salt in order to form clouds. The cloud condensation nuclei concentration will determine the cloud microphysics. An elevated portion of a frontal zone forces broad areas of lift, which form cloud decks such as altostratus or cirrostratus . Stratus

3564-457: 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

3672-747: The Aral Sea – though there is some evidence the large Pamir glaciers provided enough meltwater for the Aral to overflow during the 13th and 14th centuries. Since the end of the 19th century, there have been four different claimants as the true source of the Oxus: A glacier turns into the Wakhan River and joins the Pamir River about 50 kilometres (31 mi) downstream. Bill Colegrave's expedition to Wakhan in 2007 found that both claimants 2 and 3 had

3780-488: The Aral Sea . ~ Matthew Arnold , Sohrab and Rustum Precipitation In meteorology , precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle , rain , sleet , snow , ice pellets , graupel and hail . Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity ), so that

3888-717: The Basmachi movement and killed Ibrahim Bek . A large refugee population of Central Asians, including Turkmen, Tajiks, and Uzbeks, fled to northern Afghanistan. In the 1960s and 1970s the Soviets started using the Amu Darya and the Syr Darya to irrigate extensive cotton fields in the Central Asian plain. Before this time, water from the rivers was already being used for agriculture, but not on this massive scale. The Qaraqum Canal , Karshi Canal, and Bukhara Canal were among

3996-678: The Great Basin and Mojave Deserts . Similarly, in Asia, the Himalaya mountains create an obstacle to monsoons which leads to extremely high precipitation on the southern side and lower precipitation levels on the northern side. Extratropical cyclones can bring cold and dangerous conditions with heavy rain and snow with winds exceeding 119 km/h (74 mph), (sometimes referred to as windstorms in Europe). The band of precipitation that

4104-477: The Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Global warming is already causing changes to weather, increasing precipitation in some geographies, and reducing it in others, resulting in additional extreme weather . Precipitation may occur on other celestial bodies. Saturn's largest satellite , Titan , hosts methane precipitation as

4212-675: The Levant through Persia to Afghanistan , with the Oxus as his stated goal, "to see certain famous monuments, chiefly the Gonbad-e Qabus , a tower built as a mausoleum for an ancient king." George MacDonald Fraser 's Flashman at the Charge (1973), places Flashman on the Amu Darya and the Aral Sea during the (fictitious) Russian advance on India during The Great Game period. But

4320-680: The Pamirs passing the Tajikistan–Afghanistan Friendship Bridge . It subsequently forms the border of Afghanistan and Uzbekistan for about 200 kilometres (120 mi), passing Termez and the Afghanistan–Uzbekistan Friendship Bridge . It delineates the border of Afghanistan and Turkmenistan for another 100 kilometres (62 mi) before it flows into Turkmenistan at Atamurat . It flows across Turkmenistan south to north, passing Türkmenabat , and forms

4428-536: The Sasanian period the river is known as Wehrōd (lit. 'good river'). The name Amu is said to have come from the medieval city of Āmul (later Chahar Joy/Charjunow, and now known as Türkmenabat ) in modern Turkmenistan , with Daryā being the Persian word for 'lake' or 'sea'. Medieval Arabic and Islamic sources call the river Jeyhoun ( Arabic : جَـيْـحُـوْن , romanized :  Jayḥūn ), which

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4536-547: The Transcaspian Canal . The 534,769 square kilometres (206,475 sq mi) of the Amu Darya drainage basin include most of Tajikistan, the southwest corner of Kyrgyzstan , the northeast corner of Afghanistan, a narrow portion of eastern Turkmenistan and the western half of Uzbekistan. Part of the Amu Darya basin divide in Tajikistan forms that country's border with China (in the east) and Pakistan (to

4644-749: The Umayyads during the Muslim conquest of Transoxiana , and it was not until 750/1 that the Abbasids finally established direct control over it. A branch of the Banijurids of Tokharistan ruled over the area under the Abbasids, and acknowledged the suzerainty of the Samanids in the 10th century. The area apparently retained an autonomous line of rulers in the 11th–12th centuries, when it came first under

4752-459: The electromagnetic spectrum that theory and practice show are related to the occurrence and intensity of precipitation. The sensors are almost exclusively passive, recording what they see, similar to a camera, in contrast to active sensors ( radar , lidar ) that send out a signal and detect its impact on the area being observed. Satellite sensors now in practical use for precipitation fall into two categories. Thermal infrared (IR) sensors record

4860-446: 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. Precipitation may occur on celestial bodies other than Earth. When it gets cold, Mars has precipitation that most likely takes

4968-425: The return period or frequency. The intensity of a storm can be predicted for any return period and storm duration, from charts based on historical data for the location. The term 1 in 10 year storm describes a rainfall event which is rare and is only likely to occur once every 10 years, so it has a 10 percent likelihood any given year. The rainfall will be greater and the flooding will be worse than

5076-585: The Amu Darya basin. During the Soviet era, a resource-sharing system was instated in which Kyrgyzstan and Tajikistan shared water originating from the Amu and Syr Daryas with Kazakhstan , Turkmenistan , and Uzbekistan in summer. In return, Kyrgyzstan and Tajikistan received Kazakh, Turkmen, and Uzbek coal, gas, and electricity in winter. After the fall of the Soviet Union this system disintegrated and

5184-473: The Amu Darya would not exist—because it rarely rains in the lowlands through which most of the river flows. Of the total drainage area, only about 200,000 square kilometres (77,000 sq mi) actively contribute water to the river. This is because many of the river's major tributaries (especially the Zeravshan River ) have been diverted, and much of the river's drainage is arid. Throughout most of

5292-537: The Central Asian nations have failed to reinstate it. Inadequate infrastructure, poor water management, and outdated irrigation methods all exacerbate the issue. The Caspian tiger used to occur along the river's banks. After its extirpation, the Darya's delta was suggested as a potential site for the introduction of its closest surviving relative, the Siberian tiger . A feasibility study was initiated to investigate if

5400-610: The Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in). Mechanisms of producing precipitation include convective, stratiform , and orographic rainfall. Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with

5508-514: The Empire of Russia, which at the time wielded great influence over the Oxus area, would overcome these obstacles and find a suitable route through which to invade British India – but this never came to pass. The area was taken over by Russia during the Russian conquest of Turkestan . The Soviet Union became the ruling power in the early 1920s and expelled Mohammed Alim Khan . It later put down

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5616-535: The IR data. The second category of sensor channels is in the microwave part of the electromagnetic spectrum. The frequencies in use range from about 10 gigahertz to a few hundred GHz. Channels up to about 37 GHz primarily provide information on the liquid hydrometeors (rain and drizzle) in the lower parts of clouds, with larger amounts of liquid emitting higher amounts of microwave radiant energy . Channels above 37 GHz display emission signals, but are dominated by

5724-741: The Mongols came to the area, they used the water of the Amu Darya to flood Konye-Urgench . One southern route of the Silk Road ran along part of the Amu Darya northwestward from Termez before going westwards to the Caspian Sea . According to the Quaternary International, it is possible that the Amu Darya's course across the Karakum Desert has gone through several major shifts in the past few thousand years. Much of

5832-807: The Northern Hemisphere, poleward is towards the North Pole, or north. Within the Southern Hemisphere, poleward is towards the South Pole, or south. Southwest of extratropical cyclones, curved cyclonic flow bringing cold air across the relatively warm water bodies can lead to narrow lake-effect snow bands. Those bands bring strong localized snowfall which can be understood as follows: Large water bodies such as lakes efficiently store heat that results in significant temperature differences (larger than 13 °C or 23 °F) between

5940-1000: The action of solid hydrometeors (snow, graupel, etc.) to scatter microwave radiant energy. Satellites such as the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) mission employ microwave sensors to form precipitation estimates. Additional sensor channels and products have been demonstrated to provide additional useful information including visible channels, additional IR channels, water vapor channels and atmospheric sounding retrievals. However, most precipitation data sets in current use do not employ these data sources. The IR estimates have rather low skill at short time and space scales, but are available very frequently (15 minutes or more often) from satellites in geosynchronous Earth orbit. IR works best in cases of deep, vigorous convection—such as

6048-408: The area is suitable and if such an initiative would receive support from relevant decision makers. A viable tiger population of about 100 animals would require at least 5,000 km (1,900 sq mi) of large tracts of contiguous habitat with rich prey populations. Such habitat is not available at this stage and cannot be provided in the short term. The proposed region is therefore unsuitable for

6156-497: The atmosphere are known as hydrometeors. Formations due to condensation, such as clouds, haze , fog, and mist, are composed of hydrometeors. All precipitation types are made up of hydrometeors by definition, including virga , which is precipitation which evaporates before reaching the ground. Particles blown from the Earth's surface by wind, such as blowing snow and blowing sea spray, are also hydrometeors , as are hail and snow . Although surface precipitation gauges are considered

6264-413: The atmosphere due to their mass, and may collide and stick together in clusters, or aggregates. These aggregates are snowflakes, and are usually the type of ice particle that falls to the ground. Guinness World Records list the world's largest snowflakes as those of January 1887 at Fort Keogh , Montana; allegedly one measured 38 cm (15 in) wide. The exact details of the sticking mechanism remain

6372-484: The average time between observations exceeds three hours. This several-hour interval is insufficient to adequately document precipitation because of the transient nature of most precipitation systems as well as the inability of a single satellite to appropriately capture the typical daily cycle of precipitation at a given location. Since the late 1990s, several algorithms have been developed to combine precipitation data from multiple satellites' sensors, seeking to emphasize

6480-531: The best analyses of gauge data take two months or more after the observation time to undergo the necessary transmission, assembly, processing and quality control. Thus, precipitation estimates that include gauge data tend to be produced further after the observation time than the no-gauge estimates. As a result, while estimates that include gauge data may provide a more accurate depiction of the "true" precipitation, they are generally not suited for real- or near-real-time applications. The work described has resulted in

6588-420: The best instantaneous satellite estimate. In either case, the less-emphasized goal is also considered desirable. One key aspect of multi-satellite studies is the ability to include even a small amount of surface gauge data, which can be very useful for controlling the biases that are endemic to satellite estimates. The difficulties in using gauge data are that 1) their availability is limited, as noted above, and 2)

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6696-478: The border of Turkmenistan and Uzbekistan from Halkabat. It is then split by the Tuyamuyun Hydro Complex into many waterways that used to form the river delta joining the Aral Sea, passing Urgench , Daşoguz , and other cities, but it does not reach what is left of the sea any more and is lost in the desert. Use of water from the Amu Darya for irrigation has been a major contributing factor to

6804-548: The canal with the Taliban. The Taliban has made the canal a priority, with images supplied by Planet Labs demonstrate that from April 2022 to February 2023, more than 100 km of canal was excavated. According to the Taliban, the initiative is expected to convert 550,000 hectares of desert into farmland. In January 2023, the Xinjiang Central Asia Petroleum and Gas Company (aka CAPEIC) signed

6912-532: The changing temperature and humidity within the atmosphere through which they fall on their way to the ground. The METAR code for snow is SN, while snow showers are coded SHSN. Diamond dust, also known as ice needles or ice crystals, forms at temperatures approaching −40 °C (−40 °F) due to air with slightly higher moisture from aloft mixing with colder, surface-based air. They are made of simple ice crystals, hexagonal in shape. The METAR identifier for diamond dust within international hourly weather reports

7020-462: The coding of GS, which is short for the French word grésil. Stones just larger than golf ball-sized are one of the most frequently reported hail sizes. Hailstones can grow to 15 centimetres (6 in) and weigh more than 500 grams (1 lb). In large hailstones, latent heat released by further freezing may melt the outer shell of the hailstone. The hailstone then may undergo 'wet growth', where

7128-526: The communities of "the vassal Khanates of Maimene, Khulm, Kunduz, and even the Badakshan and Wahkran." An Englishman, William Moorcroft , visited the Oxus around 1824 during the Great Game period. Another Englishman, a naval officer called John Wood , came with an expedition to find the source of the river in 1839. He found modern-day Lake Zorkul , called it Lake Victoria, and proclaimed he had found

7236-424: The deeper the clouds get, and the greater the precipitation rate becomes. In mountainous areas, heavy snowfall accumulates when air is forced to ascend the mountains and squeeze out precipitation along their windward slopes, which in cold conditions, falls in the form of snow. Because of the ruggedness of terrain, forecasting the location of heavy snowfall remains a significant challenge. The wet, or rainy, season

7344-531: 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 has the second-highest average annual rainfall on Earth, with 12,000 millimetres (460 in). Storm systems affect the state with heavy rains between October and March. Local climates vary considerably on each island due to their topography, divisible into windward ( Koʻolau ) and leeward ( Kona ) regions based upon location relative to

7452-548: The equator in Colombia are amongst the wettest places on Earth. North and south of this are regions of descending air that form subtropical ridges where precipitation is low; the land surface underneath these ridges is usually arid, and these regions make up most of the Earth's deserts. An exception to this rule is in Hawaii, where upslope flow due to the trade winds lead to one of the wettest locations on Earth. Otherwise,

7560-458: The first harvest, which occurs late in the wet season. 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

7668-737: The flow of the Westerlies into the Rocky Mountains lead to the wettest, and at elevation snowiest, locations within North America. In Asia during the wet season, the flow of moist air into the Himalayas leads to some of the greatest rainfall amounts measured on Earth in northeast India. The standard way of measuring rainfall or snowfall is the standard rain gauge, which can be found in 10 cm (3.9 in) plastic and 20 cm (7.9 in) metal varieties. The inner cylinder

7776-579: The form of ice needles, rather than rain or snow. 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 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

7884-400: The funnel needs to be removed before the event begins. For those looking to measure rainfall 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

7992-425: The gauge. Once the snowfall/ice is finished accumulating, or as 30 cm (12 in) is approached, one can either bring it inside to melt, or use lukewarm water to fill the inner cylinder with in order to melt the frozen precipitation in the outer cylinder, keeping track of the warm fluid added, which is subsequently subtracted from the overall total once all the ice/snow is melted. Other types of gauges include

8100-463: The hailstones to the upper part of the cloud. The updraft dissipates and the hailstones fall down, back into the updraft, and are lifted again. Hail has a diameter of 5 millimetres (0.20 in) or more. Within METAR code, GR is used to indicate larger hail, of a diameter of at least 6.4 millimetres (0.25 in). GR is derived from the French word grêle. Smaller-sized hail, as well as snow pellets, use

8208-487: 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 desertlike climate just downwind across western Argentina. The Sierra Nevada range creates the same effect in North America forming

8316-479: The ice crystals the crystals are able to grow to hundreds of micrometers in size at the expense of the water droplets. This process is known as the Wegener–Bergeron–Findeisen process . The corresponding depletion of water vapor causes the droplets to evaporate, meaning that the ice crystals grow at the droplets' expense. These large crystals are an efficient source of precipitation, since they fall through

8424-570: The largest of the irrigation diversions built. However, the Main Turkmen Canal , which would have diverted water along the dry Uzboy River bed into central Turkmenistan, was never built. In the course of the Soviet–Afghan War in the 1970s, Soviet forces used the valley to invade Afghanistan through Termez . The Soviet Union fell in the 1990s and Central Asia split up into the many smaller countries that lie within or partially within

8532-565: The latter's disintegration in the mid-14th century. In the 16th century, the Shaybanids took over Khuttal, and the name itself ceases to be used, being replaced by Kulob . This Tajikistan location article is a stub . You can help Misplaced Pages by expanding it . Amu Darya In classical antiquity , the river was known as the Ōxus in Latin and Ὦξος ( Ôxos ) in Greek —

8640-416: The leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation occurs within the tropics and is caused by convection . The movement of the monsoon trough , or Intertropical Convergence Zone , brings rainy seasons to savannah regions. Precipitation is a major component of the water cycle , and is responsible for depositing fresh water on

8748-454: The liquid outer shell collects other smaller hailstones. The hailstone gains an ice layer and grows increasingly larger with each ascent. Once a hailstone becomes too heavy to be supported by the storm's updraft, it falls from the cloud. Snow crystals form when tiny supercooled cloud droplets (about 10 μm in diameter) freeze. Once a droplet has frozen, it grows in the supersaturated environment. Because water droplets are more numerous than

8856-789: The loose control of the Ghaznavids , and after the middle of the 11th century of the Seljuq Empire . With the decline of Seljuq power, Khuttal passed to the control of the Ghurids and the Khwarazmshahs , under whom no native princely line is known. In the 13th century Khuttal became a part of the Mongol Empire and of its successor, the Chagatai Khanate , emerging once again as an autonomous principality following

8964-514: The main stem and the Uzboy. But in the 18th century, the river again turned north, flowing into the Aral Sea, a path it has taken since. Less and less water flowed down the Uzboy. When Russian explorer Bekovich-Cherkasski surveyed the region in 1720, the Amu Darya did not flow into the Caspian Sea anymore. By the 1800s, the ethnographic makeup of the region was described by Peter Kropotkin as

9072-445: The majestic River floated on, Out of the mist and hum of that low land, Into the frosty starlight, and there moved, Rejoicing, through the hushed Chorasmian waste, Under the solitary moon: — he flowed Right for the polar star, past Orgunjè, Brimming, and bright, and large: then sands begin To hem his watery march, and dam his streams, And split his currents; that for many

9180-462: The planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year: 398,000 cubic kilometres (95,000 cu mi) over oceans and 107,000 cubic kilometres (26,000 cu mi) over land. Given the Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in), but over land it is only 715 millimetres (28.1 in). Climate classification systems such as

9288-424: The popular wedge gauge (the cheapest rain gauge and most fragile), the tipping bucket rain gauge , and the weighing rain gauge . The wedge and tipping bucket gauges have problems with snow. Attempts to compensate for snow/ice by warming the tipping bucket meet with limited success, since snow may sublimate if the gauge is kept much above freezing. Weighing gauges with antifreeze should do fine with snow, but again,

9396-490: 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. On the large scale, the highest precipitation amounts outside topography fall in the tropics, closely tied to the Intertropical Convergence Zone , itself the ascending branch of the Hadley cell . Mountainous locales near

9504-581: 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

9612-402: The reintroduction, at least at this stage. Since March 2022, the building of the 285 km Qosh Tepa Canal has been underway in northern Afghanistan to divert water from the Amu Darya. Uzbekistan has expressed concern that the canal will have an adverse effect on its agriculture. The canal is also expected to make the Aral Sea disaster worse, and in 2023 Uzbek officials held talks on

9720-406: 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. These gauges are used in the winter by removing the funnel and inner cylinder and allowing snow and freezing rain to collect inside the outer cylinder. Some add anti-freeze to their gauge so they do not have to melt the snow or ice that falls into

9828-413: The result at the surface. A temperature profile showing a warm layer above the ground is most likely to be found in advance of a warm front during the cold season, but can occasionally be found behind a passing cold front . Like other precipitation, hail forms in storm clouds when supercooled water droplets freeze on contact with condensation nuclei , such as dust or dirt. The storm's updraft blows

9936-438: 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

10044-655: The river Jaihun . ~ Mirza Nathan describing a battle between the Mughals and Musa Khan of Bengal (translated by M. I. Borah) The Oxus river, and Arnold's poem, fire the imaginations of the children who adventure with ponies over the moors of the West Country in the 1930s children's book The Far-Distant Oxus . There were two sequels, Escape to Persia and Oxus in Summer . Robert Byron 's 1937 travelogue, The Road to Oxiana , describes its author's journey from

10152-630: The same source, the Chelab stream, which bifurcates on the watershed of the Little Pamir, half flowing into Lake Chamaktin and half into the parent stream of the Little Pamir/Sarhad River. Therefore, the Chelab stream may be properly considered the true source or parent stream of the Oxus. The Panj River forms the border of Afghanistan and Tajikistan . It flows west to Ishkashim where it turns north and then north-west through

10260-527: The shrinking of the Aral Sea since the late 1950s. Historical records state that in different periods, the river flowed into the Aral Sea (from the south), into the Caspian Sea (from the east), or both, similar to the Syr Darya (Jaxartes, in Ancient Greek ). Partly based on such records, first Tsarist and later Soviet engineers proposed to divert the Amu Darya to the Caspian Sea by constructing

10368-515: The source. Then, the French explorer and geographer Thibaut Viné collected a lot of information about this area during five expeditions between 1856 and 1862. The question of finding a route between the Oxus valley and India has been of concern historically. A direct route crosses extremely high mountain passes in the Hindu Kush and isolated areas like Kafiristan . Some in Britain feared that

10476-475: The south). About 61% of the drainage lies within Tajikistan, Uzbekistan and Turkmenistan, while 39% is in Afghanistan. The abundant water flowing in the Amu Darya comes almost entirely from glaciers in the Pamir Mountains and Tian Shan , which, standing above the surrounding arid plain, collect atmospheric moisture which otherwise would probably escape elsewhere. Without its mountain water sources,

10584-455: The standard for measuring precipitation, there are many areas in which their use is not feasible. This includes the vast expanses of ocean and remote land areas. In other cases, social, technical or administrative issues prevent the dissemination of gauge observations. As a result, the modern global record of precipitation largely depends on satellite observations. Satellite sensors work by remotely sensing precipitation—recording various parts of

10692-510: The steppe, the annual rainfall is about 300 millimetres (12 in). The ancient Greeks called the Amu Darya the Oxus . In ancient times, the river was regarded as the boundary between Greater Iran and Ṫūrān ( Persian : تُوران ). The river's drainage lies in the area between the former empires of Genghis Khan and Alexander the Great , although they occurred at very different times. When

10800-565: The strengths and minimize the weaknesses of the individual input data sets. The goal is to provide "best" estimates of precipitation on a uniform time/space grid, usually for as much of the globe as possible. In some cases the long-term homogeneity of the dataset is emphasized, which is the Climate Data Record standard. Alternatively, the High Resolution Precipitation Product aims to produce

10908-424: The surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include rain and drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles , ice pellets , hail , and graupel . The dew point

11016-521: The time – most recently from the 13th century to the late 16th century – the Amu Darya emptied into both the Aral and the Caspian Seas, reaching the latter via a large distributary called the Uzboy River . The Uzboy splits off from the main channel just south of the river's delta. Sometimes the flow through the two branches was more or less equal, but often most of the Amu Darya's flow split to

11124-437: The tropics—and becomes progressively less useful in areas where stratiform (layered) precipitation dominates, especially in mid- and high-latitude regions. The more-direct physical connection between hydrometeors and microwave channels gives the microwave estimates greater skill on short time and space scales than is true for IR. However, microwave sensors fly only on low Earth orbit satellites, and there are few enough of them that

11232-495: The water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation; their water vapor does not condense sufficiently to precipitate, so fog and mist do not fall. (Such a non-precipitating combination is a colloid .) Two processes, possibly acting together, can lead to air becoming saturated with water vapor: cooling the air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within

11340-405: The water surface and the air above. Because of this temperature difference, warmth and moisture are transported upward, condensing into vertically oriented clouds (see satellite picture) which produce snow showers. The temperature decrease with height and cloud depth are directly affected by both the water temperature and the large-scale environment. The stronger the temperature decrease with height,

11448-492: The west and flowed into the Caspian. People began to settle along the lower Amu Darya and the Uzboy in the 5th century, establishing a thriving chain of agricultural lands, towns, and cities. In about AD 985, the massive Gurganj Dam at the bifurcation of the forks started to divert water to the Aral. Genghis Khan 's troops destroyed the dam in 1221, and the Amu Darya shifted to distributing its flow more or less equally between

11556-447: 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 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

11664-438: The worst storm expected in any single year. The term 1 in 100 year storm describes a rainfall event which is extremely rare and which will occur with a likelihood of only once in a century, so has a 1 percent likelihood in any given year. The rainfall will be extreme and flooding to be worse than a 1 in 10 year event. As with all probability events, it is possible though unlikely to have two "1 in 100 Year Storms" in

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