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1981–82 South-West Indian Ocean Cyclone Season
The 1981–82 South-West Indian Ocean cyclone season was destructive and deadly in Madagascar, where four cyclones killed 100 people and caused $250 million (USD) in damage. The season was fairly active, lasting from October to May. There were nine named storms that attained gale-force winds, or at least . Five of the storms attained tropical cyclone status, which have 10-minute sustained winds of at least . The first storm was Tropical Cyclone Alex, which was named by the Australian Bureau of Meteorology (BoM). this was due to the boundary of the basin at the time, which incorporated the Indian Ocean south of the equator and extended from the east coast of Africa to 80° E; the eastern extent was later moved to 90° E. Two other storms – Armelle and Damia – also originated in the Australian basin. The latter was the strongest cyclone on record in the basin at the time by barometric pressure, estimated at . The first storm to affect Madagascar was Bened ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1979–80 South-West Indian Ocean Cyclone Season
The 1979–80 South-West Indian Ocean cyclone season was an above-average cyclone season. The season officially ran from November 1, 1979, to April 30, 1980. Systems Tropical Cyclone Tony On 26 August, the BoM reported that a tropical low had developed on a shear line about to the northwest of Cocos Island. Over the next couple of days the depression gradually developed further before at 1800 UTC on 27 August, TCWC Perth estimated that it had become a tropical cyclone and named it Tony. During the next couple of days, the system moved towards the west-southwest before on 29 August it reached its peak intensity of and a peak pressure of as it approached the edge of TCWC Perth's area of responsibility. During the next day, Tony moved into the South West Indian Ocean and weakened gradually before it dissipated during 31 August. Neither the Mauritius or Reunion meteorological services monitored Tony as a tropical cyclone while it was active, while it was not included in the JTWC' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dvorak Technique
The Dvorak technique (developed between 1969 and 1984 by Vernon Dvorak) is a widely used system to estimate tropical cyclone intensity (which includes tropical depression, tropical storm, and hurricane/typhoon/intense tropical cyclone intensities) based solely on visible and infrared satellite images. Within the Dvorak satellite strength estimate for tropical cyclones, there are several visual patterns that a cyclone may take on which define the upper and lower bounds on its intensity. The primary patterns used are curved band pattern (T1.0-T4.5), shear pattern (T1.5–T3.5), central dense overcast (CDO) pattern (T2.5–T5.0), central cold cover (CCC) pattern, banding eye pattern (T4.0–T4.5), and eye pattern (T4.5–T8.0). Both the central dense overcast and embedded eye pattern use the size of the CDO. The CDO pattern intensities start at T2.5, equivalent to minimal tropical storm intensity (40 mph, 65 km/h). The shape of the central dense overcast is also con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christmas Island
Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the closest point on the Australian mainland. It lies northwest of Perth and south of Singapore. It has an area of . Christmas Island had a population of 1,692 residents , the majority living in settlements on the northern edge of the island. The main settlement is Flying Fish Cove. Historically, Asian Australians of Chinese, Malay, and Indian descent formed the majority of the population. Today, around two-thirds of the island's population is estimated to have Straits Chinese origin (though just 22.2% of the population declared a Chinese ancestry in 2021), with significant numbers of Malays and European Australians and smaller numbers of Straits Indians and Eurasians. Several languages are in use, including English, Malay, and various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antsiranana
Antsiranana ( mg, Antsiran̈ana ), named Diego-Suárez prior to 1975, is a city in the far north of Madagascar. Antsiranana is the capital of Diana Region. It had an estimated population of 115,015 in 2013. History The bay and city originally used the name ''Diego-Suárez'', named after Diogo Soares, a Portuguese navigator who visited the bay in 1543–44. In the 1880s, the bay was coveted by France, which desired it as a coaling station for steamships. After the first Franco-Hova War, Queen Ranavalona III signed a treaty on December 17, 1885, granting France a protectorate over the bay and surrounding territory, as well as the islands of Nosy-Be and Ste. Marie de Madagascar. The colony's administration was subsumed into that of Madagascar in 1896. The Second Pacific Squadron of Imperial Russia anchored and was resupplied at Diego-Suárez on its way to the Battle of Tsushima in 1905. In 1942, Diego-Suárez was the primary objective of Operation Ironclad, the starting point ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malawi
Malawi (; or aláwi Tumbuka: ''Malaŵi''), officially the Republic of Malawi, is a landlocked country in Southeastern Africa that was formerly known as Nyasaland. It is bordered by Zambia to the west, Tanzania to the north and northeast, and Mozambique to the east, south and southwest. Malawi spans over and has an estimated population of 19,431,566 (as of January 2021). Malawi's capital (and largest city) is Lilongwe. Its second-largest is Blantyre, its third-largest is Mzuzu and its fourth-largest is its former capital, Zomba. The name ''Malawi'' comes from the Maravi, an old name for the Chewa people who inhabit the area. The country is nicknamed "The Warm Heart of Africa" because of the friendliness of its people. The part of Africa now known as Malawi was settled around the 10th century by migrating Bantu groups . Centuries later, in 1891, the area was colonised by the British and became a protectorate of the United Kingdom known as Nyasaland. In 1953, it became ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye (cyclone)
The eye is a region of mostly calm weather at the center of tropical cyclones. The eye of a storm is a roughly circular area, typically in diameter. It is surrounded by the ''eyewall'', a ring of towering thunderstorms where the most severe weather and highest winds occur. The cyclone's lowest barometric pressure occurs in the eye and can be as much as 15 percent lower than the pressure outside the storm. In strong tropical cyclones, the eye is characterized by light winds and clear skies, surrounded on all sides by a towering, symmetric eyewall. In weaker tropical cyclones, the eye is less well defined and can be covered by the central dense overcast, an area of high, thick clouds that show up brightly on satellite imagery. Weaker or disorganized storms may also feature an eyewall that does not completely encircle the eye or have an eye that features heavy rain. In all storms, however, the eye is the location of the storm's minimum barometric pressure—where the atmospheric pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tromelin Island
Tromelin Island (; french: Île Tromelin, ) is a low, flat island in the Indian Ocean about north of Réunion and about east of Madagascar. Tromelin is administered as part of the French Southern and Antarctic Lands, a French Overseas Territory, but Mauritius claims sovereignty over the island. Tromelin has facilities for scientific expeditions and a weather station. It is a nesting site for birds and green sea turtles. Etymology The island is named in honour of Jacques Marie Boudin de Tromelin de La Nuguy, captain of the French corvette ''Dauphine''. He arrived at the island on 29 November 1776, and rescued eight stranded enslaved Malagasy people who had been on the island for 15 years. Description Tromelin is situated in the Mascarene Basin and is part of the Îles Éparses. It is currently only high. It formed as a volcano, now eroded, and developed an atoll ring of coral. Tromelin is about long and wide, with an area of 80 ha (200 acres), cover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convection (meteorology)
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes. Overview There are a few general archetypes of atmospheric instability that are used to explain convection (or lack thereof). A necessary (but not sufficient) condition for convection is that the environmental lapse rate (the rate of decrease of temperature with height) is steeper than the lapse rate experienced by a rising parcel of air. When this condition is met, upward-displaced air parcels can become buoyant an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Shear
Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude. Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on the control of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sumatra
Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent islands such as the Simeulue, Nias, Mentawai, Enggano, Riau Islands, Bangka Belitung and Krakatoa archipelago. Sumatra is an elongated landmass spanning a diagonal northwest–southeast axis. The Indian Ocean borders the northwest, west, and southwest coasts of Sumatra, with the island chain of Simeulue, Nias, Mentawai, and Enggano off the western coast. In the northeast, the narrow Strait of Malacca separates the island from the Malay Peninsula, which is an extension of the Eurasian continent. In the southeast, the narrow Sunda Strait, containing the Krakatoa Archipelago, separates Sumatra from Java. The northern tip of Sumatra is near the Andaman Islands, while off the southeastern coast lie the islands of Bangka and Belitung, Karim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-pressure Area
In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible rain or storms), while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis force, Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the Atmosphere of Earth, atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In Meteorology#Dynamic meteorology, meteorology, atmospheric divergence aloft occurs in two kinds of places: * The first is in the area on the east side of upper Trough (meteorology), troughs, which form half of a Rossby wave within the Westerlies (a trough (meteorology), trough with la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intertropical Convergence Zone
The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator though its specific position varies seasonally. When it lies near the geographic Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation, it is sometimes referred to as a monsoon trough, a usage that is more common in Australia and parts of Asia. Meteorology The ITCZ was originally identified from the 1920s to the 1940s as the ''Intertropical Front'' (''ITF''), but after the recognition in the 1940s and the 1950s of the significance of wind field convergence in tropical weather production, the term ''Intertropical Convergence Zone'' (''ITCZ'') was then applied. The ITCZ appears as a band of clouds, usually thunderstorms, that encircle the globe near the Equator. In the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
