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Subtropical Storm Alpha (2020)
Subtropical Storm Alpha was the first subtropical or tropical cyclone ever observed to make landfall in mainland Portugal. The twenty-second tropical or subtropical cyclone and twenty-first named storm of the extremely active and record-breaking 2020 Atlantic hurricane season, Alpha originated from a large non-tropical low that was first monitored by the National Hurricane Center on 15 September. Initially not anticipated to transition into a tropical cyclone, the low gradually tracked south-southeastward for several days with little development. By early on 17 September, the low had separated from its frontal features and exhibited sufficient organization to be classified as a subtropical cyclone, as it approached the Iberian Peninsula, becoming a subtropical storm around that time. Alpha then made landfall just south of Figueira da Foz, Portugal during the evening of 18 September, then rapidly weakened as it moved over the mountainous terrain of Northeastern Po ...
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Portugal
Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of the Azores and Madeira. It features the westernmost point in continental Europe, and its Iberian portion is bordered to the west and south by the Atlantic Ocean and to the north and east by Spain, the sole country to have a land border with Portugal. Its two archipelagos form two autonomous regions with their own regional governments. Lisbon is the capital and largest city by population. Portugal is the oldest continuously existing nation state on the Iberian Peninsula and one of the oldest in Europe, its territory having been continuously settled, invaded and fought over since prehistoric times. It was inhabited by pre-Celtic and Celtic peoples who had contact with Phoenicians and Ancient Greek traders, it was ruled by the Ro ...
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Extratropical Cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of producing anything from cloudiness and mild showers to severe gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale (synoptic) low pressure weather systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, about the center of the cyclone. Terminology The term " cyclone" applies to numerous types of low pressure areas, one of which is the extratropical cyclone. The descriptor ''extratropical'' signifies that this type of cyclone generally occurs outside the tropics and in the middle latitudes of Earth between 30° and 60° latitude. They are term ...
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Monte Real
Monte Real is a town (''vila'' in Portuguese) and a former civil parish in the municipality of Leiria, Portugal. In 2013, the parish merged into the new parish Monte Real e Carvide. It covers an area of 12.23 km² and has a population of 2,778 people. Monte Real, which in English means Royal Mount, was once a municipality (pt: ''concelho''), before being annexed to Leiria municipality. Monte Real hosts an air base (''base aérea''), Monte Real Air Base for the Portuguese Air Force. Monte Real is also known for its hot springs A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by circ ..., (''Termas de Monte Real''). Climate Termas de Monte Real - Portugal (37008272484).jpg Monte Real - Portugal (23864521498).jpg Igreja Paroquial de Monte Real - Portugal (23864521678).jpg Paços Reai ...
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Scatterometer
A scatterometer or diffusionmeter is a scientific instrument to measure the return of a beam of light or radar waves scattered by diffusion in a medium such as air. Diffusionmeters using visible light are found in airports or along roads to measure horizontal visibility. Radar scatterometers use radio or microwaves to determine the normalized radar cross section (σ0, "sigma zero" or "sigma naught") of a surface. They are often mounted on weather satellites to find wind speed and direction, and are used in industries to analyze the roughness of surfaces. Optical Optical diffusionmeters are devices used in meteorology to find the optical range or the horizontal visibility. They consist of a light source, usually a laser, and a receiver. Both are placed at a 35° angle downward, aimed at a common area. Lateral scattering by the air along the light beam is quantified as an attenuation coefficient. Any departure from the clear air extinction coefficient (e.g. in fog) is measured an ...
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Coordinated Universal Time
Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about one second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted as CCIR Recommendation 374, ''Standard-Frequency and Time-Signal Emissions'', in 1963, but the official abbreviation of UTC and the official English name of Coordinated Universal Time (along with the French equivalent) were not adopted until 1967. The system has been adjusted several times, including a brief period during which the time-coordination radio signals broadcast both UTC and "Stepped Atomic Time (SAT)" before a new UTC was adopted in 1970 and implemented in 1972. This change also a ...
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Convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convection is unspecified, convection due to the effects of thermal expansion and buoyancy can be assumed. Convection may also take place in soft solids or mixtures where particles can flow. Convective flow may be transient (such as when a multiphase mixture of oil and water separates) or steady state (see Convection cell). The convection may be due to gravitational, electromagnetic or fictitious body forces. Heat transfer by natural convection plays a role in the structure of Earth's atmosphere, its oceans, and its mantle. Discrete convective cells in the atmosphere can be identified by clouds, with stronger convection resulting in thunderstorms. Natural convection also plays a role in stellar physics. Convection is often categorised or d ...
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Tropical Cyclogenesis
Tropical cyclogenesis is the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which temperate cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment. Tropical cyclogenesis requires six main factors: sufficiently warm sea surface temperatures (at least ), atmospheric instability, high humidity in the lower to middle levels of the troposphere, enough Coriolis force to develop a low-pressure center, a pre-existing low-level focus or disturbance, and low vertical wind shear. Tropical cyclones tend to develop during the summer, but have been noted in nearly every month in most basins. Climate cycles such as ENSO and the Madden–Julian oscillation modulate the timing and frequency of tropical cyclone development. There is a limit on tropical cyclone i ...
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Sea Surface Temperature
Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a short distance of the shore. Localized areas of heavy snow can form in bands downwind of warm water bodies within an otherwise cold air mass. Warm sea surface temperatures are known to be a cause of tropical cyclogenesis over the Earth's oceans. Tropical cyclones can also cause a cool wake, due to turbulent mixing of the upper of the ocean. SST changes diurnally, like the air above it, but to a lesser degree. There is less SST variation on breezy days than on calm days. In addition, ocean currents such as the Atlantic Multidecadal Oscillation (AMO), can affect SST's on multi-decadal time scales, a major impact results from the global thermohaline ci ...
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Atmospheric Pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 760mm Hg, 29.9212 inchesHg, or 14.696psi.International Civil Aviation Organization. ''Manual of the ICAO Standard Atmosphere'', Doc 7488-CD, Third Edition, 1993. . The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is approximately 1 atm. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitudes—the Earth's gravi ...
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Explosive Cyclogenesis
Explosive cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, bomb cyclone, or bombogenesis) is the rapid deepening of an Extratropical cyclone, extratropical cyclonic low-pressure area. The change in pressure needed to classify something as explosive cyclogenesis is latitude dependent. For example, at 60° latitude, explosive cyclogenesis occurs if the central pressure decreases by or more in 24 hours. This is a predominantly maritime, winter event, but also occurs in continental settings, This process is the extratropical equivalent of the tropical rapid deepening. Although their cyclogenesis is entirely different from that of tropical cyclones, bomb cyclones can produce winds of , the same order as the first categories of the Saffir–Simpson scale, and yield heavy precipitation. Even though only a minority of the bomb cyclones become so strong, some weaker ones have also caused significant damage. History In the 1940s and 1950s, mete ...
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Weather Front
A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For instance, cold fronts can bring bands of thunderstorms and cumulonimbus precipitation or be preceded by squall lines, while warm fronts are usually preceded by stratiform precipitation and fog. In summer, subtler humidity gradients are known as dry lines can trigger severe weather. Some fronts produce no precipitation and little cloudiness, although there is invariably always a wind shift. Cold fronts generally move from west to east, whereas warm fronts move poleward, although any direction is possible. Occluded fronts are a hybrid merge of the two, and stationary fronts are stalled in their motion. Cold fronts and cold occlusions move faster than warm fronts and warm occlusions because the dense air behind them can lift as well as push ...
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Azores
) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores within the European Union , subdivision_type=Sovereign state , subdivision_name=Portugal , established_title=Settlement , established_date=1432 , established_title3=Autonomous status , established_date3=30 April 1976 , official_languages=Portuguese , demonym= ( en, Azorean) , capital_type= Capitals , capital = Ponta Delgada (executive) Angra do Heroísmo (judicial) Horta (legislative) , largest_city = Ponta Delgada , government_type=Autonomous Region , leader_title1=Representative of the Republic , leader_name1=Pedro Manuel dos Reis Alves Catarino , leader_title2= President of the Legislative Assembly , leader_name2= Luís Garcia , leader_title3= President of the Regional Government , leader_name3=José Manuel Bolieiro , le ...
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