In meteorology Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and short term forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century. The nineteenth century saw breakthroughs occur after observing networks developed, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth Earth's rotation is the rotation of the solid Earth around its own axis. The Earth rotates towards the east. As viewed from the North Star Polaris, the Earth turns counter-clockwise[1][2]. This is usually characterized by inward spiraling In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point winds Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial that rotate counter clockwise A clockwise motion is one that proceeds 'like the clock's hands': from the top to the right, then down and then to the left, and back to the top. In a mathematical sense, a circle defined parametrically in a positive Cartesian plane by the equations x = sin t and y = cos t is traced clockwise as t increases in value. Described another way, in the Northern Hemisphere The Northern Hemisphere is the half of a planet that is north of equator—the word hemisphere literally means 'half sphere'. It is also that half of the celestial sphere north of the celestial equator. Earth's northern hemisphere contains most of its land area and most of its human population and clockwise A clockwise motion is one that proceeds 'like the clock's hands': from the top to the right, then down and then to the left, and back to the top. In a mathematical sense, a circle defined parametrically in a positive Cartesian plane by the equations x = sin t and y = cos t is traced clockwise as t increases in value. Described another way, in the Southern Hemisphere The Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere (from the Greek word σφαιρα +ημι(half)) literally means 'half ball'. It is also that half of the celestial sphere south of the celestial equator of the Earth. Most large-scale cyclonic circulations are centered on areas of low atmospheric pressure Atmospheric pressure is the force per unit area exerted against a surface by the weight of air above that surface in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above[3][4]. The largest low-pressure systems are cold-core polar cyclones and extratropical cyclones which lie on the synoptic scale The synoptic scale in meteorology is a horizontal length scale of the order of 1000 kilometres (about 620 miles) or more. This corresponds to a horizontal scale typical of mid-latitude depressions. Most high and low pressure areas seen on weather maps such as surface weather analyses are synoptic-scale systems, driven by the location of rossby. Warm-core cyclones such as tropical cyclones, mesocyclones A mesocyclone is a vortex of air, approximately 2 to 10 km in diameter , within a convective storm. That is, it is air that rises and rotates around a vertical axis, usually in the same direction as low pressure systems in a given hemisphere. They are most often cyclonic, that is, associated with a localized low-pressure region within a severe, and polar lows lie within the smaller mesoscale 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. Subtropical cyclones are of intermediate size.[5][6] Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the Tropical Upper Tropospheric Trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on other planets outside of the Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet,[note 6] or by its Latin name, Terra.[note 7], such as Mars Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact and Neptune Neptune is the eighth and farthest planet from the Sun in our Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third-largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 Earth masses and not as dense. On average, Neptune.[7][8]
Cyclogenesis Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere . Cyclogenesis is an umbrella term for several different processes, all of which result in the development of some sort of cyclone. It can occur at various scales, from the microscale to the synoptic scale. Extratropical cyclones form as waves along weather describes the process of cyclone formation and intensification.[9] Extratropical cyclones Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere . Cyclogenesis is an umbrella term for several different processes, all of which result in the development of some sort of cyclone. It can occur at various scales, from the microscale to the synoptic scale. Extratropical cyclones form as waves along weather form as waves in large regions of enhanced midlatitude temperature contrasts called baroclinic zones In fluid dynamics, the baroclinity is a measure of the stratification in a fluid. In meteorology a baroclinic atmosphere is one for which the density depends on both the temperature and the pressure; contrast this with barotropic atmosphere, for which the density depends only on the pressure. In atmospheric terms, the barotropic zones of the Earth. These zones contract to form weather fronts A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front. The air masses separated by a front usually differ in temperature and humidity. Cold as the cyclonic circulation closes and intensifies. Later in their life cycle, cyclones occlude An occluded front is formed during the process of cyclogenesis when a cold front overtakes a warm front. When this occurs, the warm air is separated from the cyclone center at the Earth's surface. The point where the front and the occluded front meet (and consequently the nearest location of warm air to the center of the cyclone) is called the as cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the cancer or subtropical jet stream Jet streams are fast flowing, narrow air currents found in the atmospheres of some planets. The main jet streams are located near the tropopause, the transition between the troposphere and the stratosphere (where temperature increases with height). The major jet streams on Earth are westerly winds (flowing west to east). Their paths typically have.
Weather fronts separate two masses of air In meteorology, an air mass is a large volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according to latitude and their continental or maritime source regions. Colder air masses are termed polar of different densities The density of a material is defined as its mass per unit volume. The symbol of density is ρ . In some countries (for instance, in the United States), density is also defined as its weight per unit volume . The density of a substance is the reciprocal of its specific volume, a representation commonly used in thermodynamics and are associated with the most prominent meteorological phenomena A meteorological phenomenon is a weather event which can be explained by the principles of meteorology. Air masses separated by a front may differ in temperature Historically, two equivalent concepts of temperature have developed, the thermodynamic description and a microscopic explanation based on statistical physics. Since thermodynamics deals entirely with macroscopic measurements, the thermodynamic definition of temperature, first stated by Lord Kelvin, is stated entirely in empirical, measurable or humidity Humidity is the amount of water vapor in the air. Relative humidity is defined as the ratio of the partial pressure of water vapor in a parcel of air to the saturated vapor pressure of water vapor at a prescribed temperature. Humidity may also be expressed as specific humidity. Relative humidity is an important metric used in forecasting weather. Strong cold fronts typically feature narrow bands of thunderstorms A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the thunderstorm is the cumulonimbus. Thunderstorms are and severe weather Severe weather refers to any dangerous meteorological or hydro-meteorological phenomena with the potential to cause damage, serious social disruption and loss of human life, and may on occasion be preceded by squall lines A squall line is a line of severe thunderstorms that can form along and/or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front. It contains heavy precipitation, hail, frequent lightning, strong straight line winds, and possibly tornadoes and waterspouts. Severe weather, in form of strong straight-line or dry lines A dry line separates moist air from the Gulf of Mexico (to the east) and dry desert air from the south-western states (to the west). The dry line is an important factor in severe weather frequency in the Great Plains of North America. It typically lies north-south across the High Plains states in the warm sector of an extratropical cyclone and. They form west of the circulation center and generally move from west to east. Warm fronts A warm front is defined as the leading edge of an advancing mass of warm air; it separates warm air from the colder air ahead form east of the cyclone center and are usually preceded by stratiform A stratus cloud is a cloud belonging to a class characterized by horizontal layering with a uniform base, as opposed to convective clouds that are as tall or taller than wide (these are termed cumulus clouds). More specifically, the term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color from dark gray to precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that is pulled down by gravity and deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel. It occurs when the atmosphere, a large gaseous solution, becomes saturated with water vapour and the water and fog Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of a cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated locally. They move poleward A geographical pole is either of the two points—the north pole and the south pole—on the surface of a rotating planet (or other rotating body) where the axis of rotation (or simply "axis") meets the surface of the body. The north geographic pole of a body lies 90 degrees north of the equator, while the south geographic pole lies 90 ahead of the cyclone path. Occluded fronts form late in the cyclone life cycle near the center of the cyclone and often wrap around the storm center.
Tropical cyclogenesis Tropical cyclogenesis is the technical term describing 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 mid-latitude cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to describes the process of development of tropical cyclones. Tropical cyclones form due to latent heat driven by significant thunderstorm activity, and are warm core.[10] Cyclones can transition between extratropical, subtropical, and tropical phases under the right conditions. Mesocyclones form as warm core cyclones over land, and can lead to tornado A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. Tornadoes come in many shapes and sizes, but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled formation.[11] Waterspouts A waterspout is an intense columnar vortex that occurs over a body of water and is connected to a cumuliform cloud. In the common form, it is a non-supercell tornado over water. While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur. Waterspouts do not suck up water; the water seen in the can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere. Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across fronts and near the coast, and vertical shear typically near the surface,.[12]
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Structure
There are a number of structural characteristics common to all cyclones. As they are low pressure areas A low pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low pressure area is known as cyclogenesis. Within the field of atmospheric, their center is the area of lowest atmospheric pressure in the region, often known in mature tropical cyclones as the eye The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather of a cyclone occurs. The cyclone's lowest barometric pressure occurs in the.[13] Near the center, the pressure gradient force The pressure gradient force is not actually a 'force' but the acceleration of air due to pressure difference . It is usually responsible for accelerating a parcel of air from a high atmospheric pressure region to a low pressure region, resulting in wind. In meteorology, pressure gradient force refers to the horizontal movement of air according to (from the pressure in the center of the cyclone compared to the pressure outside the cyclone) and the Coriolis force In physics, the Coriolis effect is an apparent deflection of moving objects when they are viewed from a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with anti-clockwise rotation, the deflection is to the right. The mathematical expression for the Coriolis must be in an approximate balance, or the cyclone would collapse on itself as a result of the difference in pressure.[14] The wind flow around a large cyclone is counterclockwise A clockwise motion is one that proceeds 'like the clock's hands': from the top to the right, then down and then to the left, and back to the top. In a mathematical sense, a circle defined parametrically in a positive Cartesian plane by the equations x = sin t and y = cos t is traced clockwise as t increases in value. Described another way, in the northern hemisphere and clockwise in the southern hemisphere as a result of the Coriolis effect.[15] (An anticyclone An anticyclone is a weather phenomenon defined by the National Weather Service's glossary as "A large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere". Effects of surface-based anticyclones include clearing skies as well as, on the other hand, rotates clockwise in the northern hemisphere, and counterclockwise in the southern hemisphere.)
Formation
The initial extratropical low pressure area forms at the location of the red dot on the image. It is usually perpendicular (at a right angle to) the leaf-like cloud formation seen on satellite during the early stage of cyclogenesis. The location of the axis of the upper level jet stream Jet streams are fast flowing, narrow air currents found in the atmospheres of some planets. The main jet streams are located near the tropopause, the transition between the troposphere and the stratosphere (where temperature increases with height). The major jet streams on Earth are westerly winds (flowing west to east). Their paths typically have is in light blue. Main articles: Cyclogenesis Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere . Cyclogenesis is an umbrella term for several different processes, all of which result in the development of some sort of cyclone. It can occur at various scales, from the microscale to the synoptic scale. Extratropical cyclones form as waves along weather and Tropical cyclogenesis Tropical cyclogenesis is the technical term describing 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 mid-latitude cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due toCyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low pressure area).[9] Cyclogenesis is an umbrella term for several different processes, all of which result in the development of some sort of cyclone. It can occur at various scales, from the microscale to the synoptic scale. Extratropical cyclones form as waves along weather fronts A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front. The air masses separated by a front usually differ in temperature and humidity. Cold before occluding later in their life cycle as cold core cyclones. Tropical cyclones form due to latent heat driven by significant thunderstorm activity, and are warm core.[10] Mesocyclones form as warm core cyclones over land, and can lead to tornado formation.[11] Waterspouts A waterspout is an intense columnar vortex that occurs over a body of water and is connected to a cumuliform cloud. In the common form, it is a non-supercell tornado over water. While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur. Waterspouts do not suck up water; the water seen in the can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear.[12] Cyclogenesis is the opposite of cyclolysis, and has an anticyclonic (high pressure system) equivalent which deals with the formation of high pressure areas—Anticyclogenesis.[16]
The surface low has a variety of ways of forming. Topography can force a surface low when dense low-level high pressure system ridges in east of a north-south mountain barrier.[17] Mesoscale convective systems can spawn surface lows which are initially warm core.[18] The disturbance can grow into a wave-like formation along the front and the low will be positioned at the crest. Around the low, flow will become cyclonic, by definition. This rotational flow will push polar air equatorward west of the low via its trailing cold front, and warmer air with push poleward low via the warm front. Usually the cold front will move at a quicker pace than the warm front and “catch up” with it due to the slow erosion of higher density airmass located out ahead of the cyclone and the higher density airmass sweeping in behind the cyclone, usually resulting in a narrowing warm sector.[19] At this point an occluded front forms where the warm air mass is pushed upwards into a trough of warm air aloft, which is also known as a trowal.[20]
Tropical cyclones form when the energy released by the condensation of moisture in rising air causes a positive feedback loop over warm ocean waters.[21]Tropical cyclogenesis is the technical term describing the development and strengthening of a tropical cyclone in the atmosphere.[22] The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment. There are six main requirements for tropical cyclogenesis: sufficiently warm sea surface temperatures, atmospheric instability, high humidity in the lower to middle levels of the troposphere, enough Coriolis force to develop a low pressure center, a preexisting low level focus or disturbance, and low vertical wind shear.[23] An average of 86 tropical cyclones of tropical storm intensity form annually worldwide, with 47 reaching hurricane/typhoon strength, and 20 becoming intense tropical cyclones (at least Category 3 intensity on the Saffir-Simpson Hurricane Scale).[24]
Surface-based types
See also: Low pressure areaThere are six main types of cyclones: Polar cyclones, Polar lows, Extratropical cyclones, Subtropical cyclones, Tropical cyclones, and Mesocyclones
Polar cyclone
Main article: Polar cycloneA polar, sub-polar, or Arctic cyclone (also known as a polar vortex)[25] is a vast area of low pressure which strengthens in the winter and weakens in the summer.[26] A polar cyclone is a low pressure weather system, usually spanning 1,000 kilometres (620 mi) to 2,000 kilometres (1,200 mi), in which the air circulates in a counterclockwise direction in the northern hemisphere, and a clockwise direction in the southern hemisphere. In the Northern Hemisphere, the polar cyclone has two centers on average. One center lies near Baffin Island and the other over northeast Siberia.[25] In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude.[27] When the polar vortex is strong, westerly flow descends to the Earth's surface. When the polar cyclone is weak, significant cold outbreaks occur.[28]
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Mon, 09 Aug 2010 09:34:27 GMT+00:00
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Rampage (2009) mHD x264-. CyClone. Rampage (2009) mHD x264-. CyClone. Language: English 01:19:42 | 1024 x 432 | x264 1270 Kbps | 23.976 fps | AAC 6ch 128 Kbps | 797 MB Genre: Action | Crime | Drama | Thriller A man with a thirst for revenge ...
