Siberian High

The Siberian High (also Siberian Anticyclone) is a massive collection of cold dry air that accumulates in the northeastern part of Eurasia from September until April. It is usually centered on Lake Baikal.[1] It reaches its greatest size and strength in the winter when the air temperature near the center of the high-pressure area is often lower than −40 °C (−40 °F). The atmospheric pressure is often above 1,040 millibars (31 inHg). The Siberian High is the strongest semi-permanent high in the northern hemisphere and is responsible for both the lowest temperature in the Northern Hemisphere, of −67.8 °C (−90.0 °F) on 15 January 1885 at Verkhoyansk, and the highest pressure, 1083.8 mbar (108.38 kPa, 32.01 inHg) at Agata, Krasnoyarsk Krai on 31 December 1968, ever recorded.[2] The Siberian High is responsible both for severe winter cold and attendant dry conditions with little snow and few or no glaciers across Siberia, Mongolia, and China. During the summer, the Siberian High is largely replaced by the Asiatic low.

Overview

Siberian High
The plot of mean sea level pressure over the winter months shows a large area of high atmospheric pressure in the South of Siberia.

The Siberian High affects the weather patterns in most parts of the Northern Hemisphere: its influence extends as far west as Italy[3] and as far southeast as Malaysia,[4] where it is a critical component of the northeast monsoon. Occasionally a strong Siberian High can bring unusually cold weather into the tropics as far southeast as the Philippines.[5] It may block or reduce the size of low-pressure cells and generate dry weather across much of the Asian landscape with the exception of regions such as Hokuriku and the Caspian Sea coast of Iran that receive orographic rainfall from the winds it generates. As a result of the Siberian High, coastal winters in the main city of Pacific Russia Vladivostok are very cold in relation to its latitude and proximity to the ocean.

Siberian air is generally colder than Arctic air, because unlike Arctic air which forms over the sea ice around the North Pole, Siberian air forms over the cold tundra of Siberia, which does not radiate heat the same way the ice of the Arctic does.[6]

Genesis and variability

In general, the Siberian High-pressure system begins to build up at the end of August, reaches its peak in the winter, and remains strong until the end of April. Its genesis at the end of the Arctic summer is caused by the convergence of summer air flows being cooled over interior northeast Asia as days shorten. In the process of the Siberian High's formation, the upper-level jet is transferred across northern Eurasia by adiabatic cooling and descending advection, which in extreme cases creates "cold domes" that outbreak over warmer parts of East Asia.

In spite of its immense influence on the weather experienced by a large proportion of the world’s population, scientific studies of the Siberian High have been late in coming, though variability of its behavior was observed as early as the 1960s.[1] However, recent studies of observed global warming over Asia have shown that weakening of the Siberian High is a prime driver of warmer winters in almost all of inland extra-tropical Asia and even over most parts of Europe,[1] with the strongest relationship over the West Siberian Plain and significant relationships as far west as Hungary and as far southeast as Guangdong. Precipitation has also been found to be similarly inversely related to the mean central pressure of the Siberian High over almost all of Eastern Europe during the boreal winter, and similar relationships are found in southern China, whilst the opposite correlation exists over the Coromandel Coast and Sri Lanka. Other studies have suggested that the strength of the Siberian High shows an inverse correlation with the high-pressure systems over North Africa. Another correlation has been noted, a connection of a weaker Siberian High and Arctic oscillation when the Antarctic oscillation (AAO) is stronger.[7]

See also

References

  1. ^ a b c “The Siberian High and Climate Change over Middle to High-Latitude Asia” Archived 26 April 2012 at the Wayback Machine
  2. ^ Encyclopedia of world climatology by John E. Oliver, 2005, ISBN 1-402-03264-1
  3. ^ D'Arrigo, Rosanne; Jacoby, Gordon; Wilson, Rob; Panagiotopoulos, Fotis (2005). "A reconstructed Siberian High index since A.D. 1599 from Eurasian and North American tree rings". Geophysical Research Letters. 32 (5). doi:10.1029/2004GL022271.
  4. ^ Chang Chih-peh, The East Asian Monsoon; p. 55. ISBN 978-9-812-38769-1
  5. ^ "Record Chill Spreads Deep into Southeast Asia"
  6. ^ http://www.britannica.com/EBchecked/topic/542609/Siberian-anticyclone
  7. ^ Fan, Ke. "Antarctic oscillation and the dust weather frequency in North China". Geophysical Research Letters. 31. Bibcode:2004GeoRL..3110201F. doi:10.1029/2004GL019465.

Coordinates: 66°53′N 93°28′E / 66.883°N 93.467°E

Centers of action

Centers of action are extensive and almost stationary low-pressure areas or anticyclones which control the movement of atmospheric disturbances over a large area. This does not mean that the position of the center is constant over a specific area but that the monthly atmospheric pressure corresponds to a high or a low pressure.The French meteorologist Léon Teisserenc de Bort was the first in 1881 to apply this term to maxima and minima of pressure on daily charts. The main centers of action in the Northern Hemisphere are the Icelandic Low, the Aleutian Low, the Azores/Bermuda High, the Pacific High, the Siberian High (in winter), and the Asiatic Low (in summer). Sir Gilbert Walker used the same term to relate meteorological elements in a region to weather in the following season in other regions for the Southern Oscillation.

Climate of Seoul

The climate of Seoul features a humid continental/subtropical climate with dry winter, called "Dwa"/"Cwa" in the Köppen climate classification. Seoul is classed as having a temperate climate with four distinct seasons, but temperature differences between the hottest part of summer and the depths of winter are extreme. In summer the influence of the North Pacific high-pressure system brings hot, humid weather with temperatures soaring as high as 35 °C (95 °F) on occasion. In winter the city is topographically influenced by expanding Siberian High-pressure zones and prevailing west winds, temperatures dropping almost as low as -20 °C (-4 °F) in severe cold waves. The bitterly cold days tend to come in three-day cycles regulated by rising and falling pressure systems, during winter snowfall can cause frosty weather in the city. The most pleasant seasons, for most people in the city are spring and autumn, when azure blue skies and comfortable temperatures are regular. Most of Seoul's precipitation falls in the summer monsoon period between June and September, as a part of East Asian monsoon season.

East Asian Monsoon

The East Asian monsoon is a monsoonal flow that carries moist air from the Indian Ocean and Pacific Ocean to East Asia. It affects approximately one-third of the global population, influencing the climate of Japan (including Okinawa), the Koreas, Taiwan, Hong Kong, Macau, and much of Mainland China. It is driven by temperature differences between the East Asian continent and the Pacific Ocean. The East Asian monsoon is divided into a warm and wet summer monsoon and a cold and dry winter monsoon. This cold and dry winter monsoon is responsible for the aeolian dust deposition and pedogenesis that resulted in the creation of the Loess Plateau. The monsoon influences weather patterns as far north as Siberia, causing wet summers that contrast with the cold and dry winters caused by the Siberian High, which counterbalances the monsoon's effect on northerly latitudes.

In most years, the monsoonal flow shifts in a very predictable pattern, with winds being southeasterly in late June, bringing significant rainfall to the Korean Peninsula and Japan (in Taiwan and Okinawa this flow starts in May). This leads to a reliable precipitation spike in July and August. However, this pattern occasionally fails, leading to drought and crop failure. In the winter, the winds are northeasterly and the monsoonal precipitation bands move back to the south, and intense precipitation occurs over southern China and Taiwan.

The East Asian monsoon is known as jangma (장마) in Korea. In Japan the monsoon boundary is referred to as the tsuyu (梅雨) as it advances northward during the spring, while it is referred to as the shurin when the boundary retreats back southward during the autumn months. Over Japan and Korea, the monsoon boundary typically takes the form of a quasi-stationary front separating the cooler air mass associated with the Okhotsk High to the north from the hot, humid air mass associated with the subtropical ridge to the south. After the monsoon boundary passes north of a given location, it is not uncommon for daytime temperatures to exceed 32 °C (90 °F) with dewpoints of 24 °C (75 °F) or higher.

High-pressure area

A high-pressure area, high, or anticyclone, is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment.

Winds within high-pressure areas flow outward from the higher pressure areas near their centers towards the lower pressure areas further from their centers. Gravity adds to the forces causing this general movement, because the higher pressure compresses the column of air near the center of the area into greater density – and so greater weight compared to lower pressure, lower density, and lower weight of the air outside the center.

However, because the planet is rotating underneath the atmosphere, and frictional forces arise as the planetary surface drags some atmosphere with it, the air flow from center to periphery is not direct, but is twisted due to the Coriolis effect, or the merely apparent force that arise when the observer is in a rotating frame of reference. Viewed from above this twist in wind direction is in the same direction as the rotation of the planet.

The strongest high-pressure areas are associated with cold air masses which push away out of polar regions during the winter when there is less sun to warm neighboring regions. These Highs change character and weaken once they move further over relatively warmer water bodies.

Somewhat weaker but more common are high-pressure areas caused by atmospheric subsidence, that is, areas where large masses of cooler, drier air descend from an elevation of 8 to 15 km after the lower temperatures have precipitated out the water vapor.

Many of the features of Highs may be understood in context of middle- or meso-scale and relatively enduring dynamics of a planet's atmospheric circulation. For example, massive atmospheric subsidences occur as part of the descending branches of Ferrel cells and Hadley cells. Hadley cells help form the subtropical ridge, steer tropical waves and tropical cyclones across the ocean and is strongest during the summer. The subtropical ridge also helps form most of the world's deserts.

On English-language weather maps, high-pressure centers are identified by the letter H. Weather maps in other languages may use different letters or symbols.

January 2016 East Asia cold wave

In late January 2016, a cold wave struck much of East Asia, parts of mainland Southeast Asia and parts of northern South Asia, bringing record cold temperatures and snowfall to many regions. Sleet was reported in Okinawa for the first time on record, and many other regions saw their coldest temperatures in decades. Snowfall and frigid weather stranded thousands of people across four countries. At least 85 people in Taiwan died from hypothermia and cardiac arrest following a sudden drop in temperature during the weekend of January 22–24. The cold claimed a further fourteen lives in Thailand, and snowstorms resulted in six deaths across Japan. This event was driven by a fast Arctic warming that occurred within the troposphere, forcing the Arctic Oscillation to change phase rapidly from positive (in late December) to negative (in late January), facilitating the atmospheric blocking and associated Siberian high buildup.

Kalahari High

The Kalahari High is an anticyclone that forms in winter over the interior of southern Africa, replacing a summer trough. It is part of the subtropical ridge system and the reason the Kalahari is a desert. It is the descending limb of a Hadley cell.

Luodian County

Luodian County (simplified Chinese: 罗甸县; traditional Chinese: 羅甸縣; pinyin: Luódiàn Xiàn) is a county under the administration of Qiannan Buyei and Miao Autonomous Prefecture in the south of Guizhou province, China, bordering Guangxi to the south.

The climate in the area is humid subtropical, with strong monsoon influences bringing heavy rain during the summer. Winters are dry due to the influence of the Siberian high-pressure system.

The county seat and the largest town in the county is also named Luodian; it was formerly known as Longping.

The county is frequented by both Chinese and foreign geologists, with the core area of work called Big Guizhoutan, or Big Guizhou Shoal. This has been called a "treasure land for Triassic Period research."

Mesohigh

A mesohigh (sometimes called a "bubble high") is a mesoscale high-pressure area that forms beneath thunderstorms. While not always the case, it is usually associated with a mesoscale convective system. In the early stages of research on the subject, the mesohigh was often referred to as a "thunderstorm high".

Mesoscale meteorology

Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers. Examples of mesoscale weather systems are sea breezes, squall lines, and mesoscale convective complexes.

Vertical velocity often equals or exceeds horizontal velocities in mesoscale meteorological systems due to nonhydrostatic processes such as buoyant acceleration of a rising thermal or acceleration through a narrow mountain pass.

Multiple-vortex tornado

A multiple-vortex tornado is a tornado that contains several vortices (called subvortices or suction vortices) rotating around, inside of, and as part of the main vortex. The only times multiple vortices may be visible are when the tornado is first forming or when condensation and debris are balanced such that subvortices are apparent without being obscured. They can add over 100 mph to the ground-relative wind in a tornado circulation, and are responsible for most (if not all) cases where narrow arcs of extreme destruction lie right next to weak damage within tornado paths.

North American High

The North American High (also Canadian High/Anticyclone, sometimes in Europe Greenland High/Anticyclone) is an impermanent high-pressure area or anticyclone created by a formative process that occurs when cool or cold dry air settles over North America. During the summer, it is replaced with an Arctic Low, or if it moves over continental land, a North American Low.

North American Highs move eastward across the continent, often in the company of one or more low-pressure cells or cyclones. Its cold, dense air does not extend usually above 3 km (1.9 mi), lower than the Canadian Rockies. Sometimes, during the winter, it breaks free and passes over the Rockies, and brings a cold front into Southwestern United States and Mexico, freezing crops and bringing snow into Mexico's mountains, as far south as Jalisco. The high’s usual location east of the Rockies shelters it from the relatively warm Pacific Ocean and helps it maintain its strength. The average January sea level pressure at its centre is about 1,020 millibars (30.12 inches of mercury). The Canadian high often moves southeastward until it eventually reaches the Atlantic Ocean, where it merges with the Azores high. In the summer the Canadian high circulates cool, dry air to the United States east of the Rockies and parts of southern Canada.

The North American High is akin to the Siberian High of Eurasia, but it is much smaller, and it has much less influence, merely affecting the weather of the Northern Hemisphere. The sea-level pressure (atmospheric pressure) rarely, if ever, exceeds 1055.0 millibars (1055.0 hectopascals)(hPa)(SI).

Often, in the winter months, cool or cold dry air settles over the land in the vicinity of the Great Basin where it builds into a high-pressure cell or anticyclone that moves across the United States with a cold front on its leading edge. After reaching the Atlantic Ocean, the moist environment brings on changes of the qualities of the air and the dissipation of the high-pressure cell or anticyclone as the cold air warms and becomes humid.

In Europe, a portion of the North American/Canadian high usually over Greenland called the Greenland high which settles over Greenland affects northern European weather and may merge with the Scandinavian High.

North Pacific High

The North Pacific High is a semi-permanent, subtropical anticyclone located in the northeastern portion of the Pacific Ocean, located northeast of Hawaii and west of California. It is strongest during the northern hemisphere summer and shifts towards the equator during the winter, when the Aleutian Low becomes more active. It is responsible for California's typically dry summer and fall and typically wet winter and spring, as well as Hawaii's year-round trade winds.During the 2011–2017 California drought, the North Pacific High persisted longer than usual, due to a mass of warm water in the Pacific Ocean, resulting in the Ridiculously Resilient Ridge. This significantly limited the number of powerful winter storms that were able to reach California, resulting in historic drought conditions in the state for several years.

Rapid intensification

Rapid intensification is a meteorological condition that occurs when a tropical cyclone intensifies dramatically in a short period of time. The United States National Hurricane Center (NHC) defines rapid intensification as an increase in the maximum 1-min sustained winds of a tropical cyclone of at least 30 knots (35 mph; 55 km/h) in a 24-hour period.

Rudnaya Pristan

Rudnaya Pristan (Russian: Ру́дная При́стань, lit. Ore Wharf) is a village (selo) located at the mouth of the Rudnaya River, on the Pacific coast of Primorsky Krai. It is situated 35 km east of Dalnegorsk (also in Primorsky Krai) and approximately 514 km north of Vladivostok. Its population was 2,107 in 2010, 2,389 in 2002, and 2,947 in 1989.Lead smelting has been the town's primary industry since a plant was built there in 1930. The plant has provided steady employment for most of the area's families since that time, but at enormous cost to both the health of the residents and the local environment. The residents suffer from many health problems, including an inordinately high rate of cancer, and the soil has become heavily contaminated with lead-related by-products. The Blacksmith Institute consequently declared Rudnaya Pristan, along with Dalnegorsk, one of the ten worst polluted places on earth, although Anatoly Lebedev, leader of the ecological NGO BROK, disputes this inclusion.Despite its coastal location, Rudnaya Pristan's harbor has remained largely undeveloped, and its climate is harsh, dominated in winter by the vast Siberian high-pressure system and in summer by remnants of the East Asian monsoon. This combination results in very cold, dry winters with generally high winds, and muggy summers that provide ideal conditions for the breeding of mosquitoes.

South Pacific High

The South Pacific High is a semi-permanent subtropical anticyclone located in the southeast Pacific Ocean. The area of high atmospheric pressure and the presence of the Humboldt Current in the underlying ocean make the west coast of Peru and northern Chile extremely arid. The Sechura and Atacama deserts, as the whole climate of Chile, are heavily influenced by this semi-permanent high-pressure area. This high-pressure system plays a major role in the El Niño–Southern Oscillation (ENSO), and it is also a major source of trade winds across the equatorial Pacific.

Superstorm

A superstorm is a large, unusually-occurring, destructive storm without another distinct meteorological classification, such as hurricane or blizzard. As the term is of recent coinage and lacks a formal definition, there is some debate as to its usefulness.

Tōhoku region

The Tōhoku region (東北地方, Tōhoku-chihō), Northeast region, or Northeast Japan consists of the northeastern portion of Honshu, the largest island of Japan. This traditional region consists of six prefectures (ken): Akita, Aomori, Fukushima, Iwate, Miyagi, and Yamagata.Tōhoku retains a reputation as a remote, scenic region with a harsh climate. In the 20th century, tourism became a major industry in the Tōhoku region.

Whirlwind

A whirlwind is a weather phenomenon in which a vortex of wind (a vertically oriented rotating column of air) forms due to instabilities and turbulence created by heating and flow (current) gradients. Whirlwinds occur all over the world and in any season.

Concepts
Anticyclone
Cyclone

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