There are four main scales, or sizes of systems, dealt with in meteorology: the macroscale, the synoptic scale, the mesoscale, and the microscale. The macroscale deals with systems with global size, such as the Madden–Julian oscillation. Synoptic scale systems cover a portion of a continent, such as extratropical cyclones, with dimensions of across. The mesoscale is the next smaller scale, and often is divided into two ranges: meso-alpha phenomena range from across (the realm of the tropical cyclone), while meso-beta phenomena range from across (the scale of the mesocyclone). The microscale is the smallest of the meteorological scales, with a size under (the scale of tornadoes and waterspouts).
Meteorological scales
Cyclogenesis
Cyclogenesis | Meteorological scales
It deals with systems with global size, such as the Madden–Julian oscillation It deals with systems with global size, such as the Madden–Julian oscillation. The macroscale deals with systems with global size, such as the Madden–Julian oscillation It deals with systems with global size, such as the Madden–Julian oscillation.
we would expect what with low pressure in the northern hemisphere
user
234 significant extratropical cyclones form each winter
assistant
how does a low pressure area form?
user
Cyclogenesis is the development and strengthening of cyclonic circulations
assistant
what does the first word mean?
user
It  is the development and strengthening of cyclonic circulations in the atmosphere results in the formation of low pressure area
assistant
how is this associated with the weather?
user
Sorry. I cannot find the answer based on the context.
assistant
what are some of its related terms?
user
It is the opposite of cyclolysis
assistant
which scaled are used to measure it?
user
The macroscale, the synoptic scale, the mesoscale, and the microscale
assistant
what does the first one do?
user
There are four main scales, or sizes of systems, dealt with in meteorology: the macroscale, the synoptic scale, the mesoscale, and the microscale. The macroscale deals with systems with global size, such as the Madden–Julian oscillation. Synoptic scale systems cover a portion of a continent, such as extratropical cyclones, with dimensions of across. The mesoscale is the next smaller scale, and often is divided into two ranges: meso-alpha phenomena range from across (the realm of the tropical cyclone), while meso-beta phenomena range from across (the scale of the mesocyclone). The microscale is the smallest of the meteorological scales, with a size under (the scale of tornadoes and waterspouts).
Cyclogenesis | Meteorological scales
These horizontal dimensions are not rigid divisions but instead reflect typical sizes of phenomena having certain dynamic characteristics. For example, a system does not necessarily transition from meso-alpha to synoptic scale when its horizontal extent grows from .
Cyclogenesis | Meteorological scales
Tornadoes exist on the microscale or low end of the mesoscale gamma domain. The cycle begins when a strong thunderstorm develops a rotating mesocyclone a few miles up in the atmosphere, becoming a supercell. As rainfall in the storm increases, it drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the rotating mesocyclone towards the ground with it. As the mesocyclone approaches the ground, a visible condensation funnel appears to descend from the base of the storm, often from a rotating wall cloud.
Cyclogenesis | Tornadoes
Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere. Cyclogenesis is an umbrella term for several different processes that all result in the development of some sort of cyclone. It can occur at various scales, from the microscale to the synoptic scale. Extratropical cyclones begin as waves along weather fronts before occluding later in their life cycle as cold-core systems. However, some intense extratropical cyclones can become warm-core systems when a warm seclusion occurs. Tropical cyclones form as a result of significant convective activity, and are warm core. Mesocyclones form as warm core cyclones over land, and can lead to tornado formation.
Cyclone | Formation
As the updraft rotates, it may form what is known as a wall cloud. The wall cloud is a spinning layer of clouds descending from the mesocyclone. The wall cloud tends to form closer to the center of the mesocyclone. The wall clouds do not necessarily need a mesocyclone to form and do not always rotate. As the wall cloud descends, a funnel-shaped cloud may form at its center. This is the first stage of tornado formation. The presence of a mesocyclone is believed to be a key factor in the formation of the strong tornadoes associated with severe thunderstorms.
Cyclogenesis | Mesocyclones
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 intensity which is strongly related to the water temperatures along its path.
Tropical cyclogenesis | Introduction
A preexisting frontal boundary, as defined in surface weather analysis, is required for the development of a mid-latitude cyclone. The cyclonic flow begins around a disturbed section of the stationary front due to an upper level disturbance, such as a short wave or an upper-level trough, near a favorable quadrant of the upper level jet. However, enhanced along-frontal stretching rates in the lower troposphere can suppress the growth of extratropical cyclones.
Cyclogenesis | Precursors for development
The synoptic scale in meteorology (also known as large scale or cyclonic scale) is a horizontal length scale of the order of 1000 kilometers (about 620 miles) or more. This corresponds to a horizontal scale typical of mid-latitude depressions (e.g., extratropical cyclones). 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 waves in their respective hemisphere. Low-pressure areas and their related frontal zones occur on the leading edge of a trough within the Rossby wave pattern, while high-pressure areas form on the back edge of the trough.
Synoptic scale meteorology | Introduction
Mesocyclones range in size from mesoscale beta to microscale. The term mesocyclone is usually reserved for mid-level rotations within severe thunderstorms, and are warm core cyclones driven by latent heat of its associated thunderstorm activity. Tornadoes form in the warm sector of extratropical cyclones where a strong upper level jet stream exists. Mesocyclones are believed to form when strong changes of wind speed and/or direction with height ("wind shear") sets parts of the lower part of the atmosphere spinning in invisible tube-like rolls. The convective updraft of a thunderstorm is then thought to draw up this spinning air, tilting the rolls' orientation upward (from parallel to the ground to perpendicular) and causing the entire updraft to rotate as a vertical column.
Cyclogenesis | Mesocyclones
The Norwegian cyclone model is an idealized formation model of cold-core cyclonic storms developed by Norwegian meteorologists during the First World War. The main concept behind this model, relating to cyclogenesis, is that cyclones progress through a predictable evolution as they move up a frontal boundary, with the most mature cyclone near the northeast end of the front and the least mature near the tail end of the front.
Cyclogenesis | Norwegian cyclone model
Subtropical cyclones are of intermediate size. Cyclogenesis can occur at various scales, from the microscale to the synoptic scale. Larger-scale troughs, also called Rossby waves, are synoptic in scale. Shortwave troughs embedded within the flow around larger scale troughs are smaller in scale, or mesoscale in nature. Both Rossby waves and shortwaves embedded within the flow around Rossby waves migrate equatorward of the polar cyclones located in both the Northern and Southern hemispheres. All share one important aspect, that of upward vertical motion within the troposphere. Such upward motions decrease the mass of local atmospheric columns of air, which lowers surface pressure.
Low-pressure area | Formation
Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale. The process in which an extratropical cyclone undergoes a rapid drop in atmospheric pressure (24 millibars or more) in a 24-hour period is referred to as explosive cyclogenesis, and is usually present during the formation of a nor'easter. The anticyclonic equivalent, the process of formation of high pressure areas, is anticyclogenesis.
Cyclogenesis | Introduction
Microscale meteorology is the study of atmospheric phenomena on a scale of about or less. Individual thunderstorms, clouds, and local turbulence caused by buildings and other obstacles (such as individual hills) are modeled on this scale.
Meteorology | Microscale
Such upward motions decrease the mass of local atmospheric columns of air, which lower surface pressure.
Cyclogenesis | Modes of development
In smaller systems, the development of a significant mesoscale convective complex in a sheared environment can send out a large enough outflow boundary to destroy the surface cyclone. Moderate wind shear can lead to the initial development of the convective complex and surface low similar to the mid-latitudes, but it must relax to allow tropical cyclogenesis to continue.
Tropical cyclogenesis | Weak vertical wind shear
These warm core cyclones tend to form over the oceans between 10 and 30 degrees of the equator.
Cyclogenesis | Tropical cyclones
Misoscale is an unofficial scale of meteorological phenomena that ranges in size from 40 meters to about 4 kilometers. This scale was proposed by Ted Fujita, the father of the Fujita scale, to classify phenomenon of the order of the rotation within a thunderstorm, the scale of the funnel cloud of a tornado, and the size of the swath of destruction of a microburst. It is a subdivision of the microscale.
Misoscale meteorology | Introduction
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.
Tropical cyclogenesis | Introduction
Tropical cyclones exist within a mesoscale alpha domain. As opposed to mid-latitude cyclogenesis, tropical cyclogenesis is driven by strong convection organised into a central core with no baroclinic zones, or fronts, extending through their center. Although the formation of tropical cyclones is the topic of extensive ongoing research and is still not fully understood, there are six main requirements for tropical cyclogenesis: sea surface temperatures that are warm enough, atmospheric instability, high humidity in 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.
Cyclogenesis | Tropical cyclones
The majority of extratropical cyclones tend to restrengthen after completing the transition period.
Tropical cyclogenesis | Middle latitudes
Under a cold cyclone, 500 hPa temperatures can fall as low as −30 °C, which can initiate convection even in the driest atmospheres. This also explains why moisture in the mid-levels of the troposphere, roughly at the 500 hPa level, is normally a requirement for development. However, when dry air is found at the same height, temperatures at 500 hPa need to be even colder as dry atmospheres require a greater lapse rate for instability than moist atmospheres. At heights near the tropopause, the 30-year average temperature (as measured in the period encompassing 1961 through 1990) was −77 °C (−105 °F).
Tropical cyclogenesis | Warm waters, instability, and mid-level moisture
This potential energy sink creates a kinetic energy source which injects a final burst of energy into the storm's motions. After this process occurs, the growth period of the cyclone, or cyclogenesis, ends, and the low begins to spin down (fill) as more air is converging into the bottom of the cyclone than is being removed out the top since upper-level divergence has decreased. Occasionally, cyclogenesis will re-occur with occluded cyclones. When this happens a new low center will form on the triple-point (the point where the cold front, warm front, and occluded front meet). During triple-point cyclogenesis, the occluded parent low will fill as the secondary low deepens into the main weathermaker.
Cyclogenesis | Maturity
Most precipitation areas occur near frontal zones. The word "synoptic" is derived from the Greek word (""), meaning "seen together". The Navier–Stokes equations applied to atmospheric motion can be simplified by scale analysis in the synoptic scale. It can be shown that the main terms in horizontal equations are Coriolis force and pressure gradient terms; therefore, one can use geostrophic approximation. In vertical coordinates, the momentum equation simplifies to the hydrostatic equilibrium equation.
Synoptic scale meteorology | Introduction
In a moist atmosphere, this lapse rate is 6.5 °C/km, while in an atmosphere with less than 100% relative humidity, the required lapse rate is 9.8 °C/km. At the 500 hPa level, the air temperature averages −7 °C (18 °F) within the tropics, but air in the tropics is normally dry at this level, giving the air room to wet-bulb, or cool as it moistens, to a more favorable temperature that can then support convection. A wetbulb temperature at 500 hPa in a tropical atmosphere of −13.2 °C is required to initiate convection if the water temperature is 26.5 °C, and this temperature requirement increases or decreases proportionally by 1 °C in the sea surface temperature for each 1 °C change at 500 hpa.
Tropical cyclogenesis | Warm waters, instability, and mid-level moisture
Maturity is after the time of occlusion when the storm has completed strengthening and the cyclonic flow is at its most intense. Thereafter, the strength of the storm diminishes as the cyclone couples with the upper level trough or upper level low, becoming increasingly cold core. The spin-down of cyclones, also known as cyclolysis, can be understood from an energetics perspective. As occlusion occurs and the warm air mass is pushed upwards over a cold air airmass, the atmosphere becomes increasingly stable and the centre of gravity of the system lowers. As the occlusion process extends further down the warm front and away from the central low, more and more of the available potential energy of the system is exhausted.
Cyclogenesis | Maturity
Mesoscale Meteorology is divided into these subclasses: As a note, tropical and subtropical cyclones are classified by National Hurricane Center as synoptic scale rather than mesoscale.
Mesoscale meteorology | Subclasses
Microscale meteorology is the study of short-lived atmospheric phenomena smaller than mesoscale, about 1 km or less. These two branches of meteorology are sometimes grouped together as "mesoscale and microscale meteorology" (MMM) and together study all phenomena smaller than synoptic scale; that is they study features generally too small to be depicted on a weather map. These include small and generally fleeting cloud "puffs" and other small cloud features. Microscale meteorology controls the most important mixing and dilution processes in the atmosphere. Important topics in microscale meteorology include heat transfer and gas exchange between soil, vegetation, and/or surface water and the atmosphere caused by near-ground turbulence.
Microscale meteorology | Introduction
Cyclogenesis is the development and strengthening of cyclonic circulations, or low-pressure areas, within the atmosphere. Cyclogenesis is the opposite of , and has an anticyclonic (high-pressure system) equivalent which deals with the formation of high-pressure areas—anticyclogenesis. Cyclogenesis is an umbrella term for several different processes, all of which result in the development of some sort of cyclone. Meteorologists use the term "cyclone" where circular pressure systems flow in the direction of the Earth's rotation, which normally coincides with areas of low pressure. The largest low-pressure systems are cold-core polar cyclones and extratropical cyclones which lie on the synoptic scale. Warm-core cyclones such as tropical cyclones, mesocyclones, and polar lows lie within the smaller mesoscale.
Low-pressure area | Formation
Synoptic scale meteorology predicts atmospheric changes at scales up to 1000 km and 10 sec (28 days), in time and space. At the synoptic scale, the Coriolis acceleration acting on moving air masses (outside of the tropics) plays a dominant role in predictions. The phenomena typically described by synoptic meteorology include events such as extratropical cyclones, baroclinic troughs and ridges, frontal zones, and to some extent jet streams. All of these are typically given on weather maps for a specific time. The minimum horizontal scale of synoptic phenomena is limited to the spacing between surface observation stations.
Meteorology | Synoptic scale
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.
Mesoscale meteorology | Introduction
Cyclogenesis is the opposite of cyclolysis, which concerns the weakening of surface cyclones. The term has an anticyclonic (high pressure system) equivalent—Anticyclogenesis, which deals with the formation of surface high pressure systems.
Cyclogenesis | Related terms
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 pre-existing low level focus or disturbance, and low vertical wind shear. While these conditions are necessary for tropical cyclone formation, they do not guarantee that a tropical cyclone will form. Normally, an ocean temperature of 26.5 °C (79.7 °F) spanning through a depth of at least is considered the minimum to maintain the special mesocyclone that is the tropical cyclone. These warm waters are needed to maintain the warm core that fuels tropical systems.
Typhoon | Genesis
Waterspouts exist on the microscale. While some waterspouts are strong (tornadic) like their land-based counterparts, most are much weaker and caused by different atmospheric dynamics. They normally develop in moisture-laden environments with little vertical wind shear along lines of convergence, such as land breezes, lines of frictional convergence from nearby landmasses, or surface troughs. Their parent cloud can be as innocuous as a moderate cumulus, or as significant as a thunderstorm. Waterspouts normally develop as their parent clouds are in the process of development, and it is theorized that they spin up as they move up the surface boundary from the horizontal wind shear near the surface, and then stretch upwards to the cloud once the low level shear vortex aligns with a developing cumulus or thunderstorm.
Cyclogenesis | Waterspouts
The existence of a significant Coriolis force allows the developing vortex to achieve gradient wind balance. This is a balance condition found in mature tropical cyclones that allows latent heat to concentrate near the storm core; this results in the maintenance or intensification of the vortex if other development factors are neutral.
Tropical cyclogenesis | Coriolis force
Due to the initial cold temperatures aloft, sea surface temperatures usually need to reach at least for this initial round of thunderstorms. The initial thunderstorm activity moistens up the environment around the low, which destabilizes the atmosphere by reducing the lapse rate needed for convection. When the next shortwave or upper level jet streak (wind maximum within the jet stream) moves nearby, convection reignites closer to the center and the system develops into a true subtropical cyclone. The average sea surface temperature that helps lead to subtropical cyclogenesis is . If the thunderstorm activity becomes deep and persistent, allowing its initial low level warm core to deepen, tropical cyclogenesis is possible.
Subtropical cyclone | Formation
As the funnel descends, the RFD also reaches the ground, creating a gust front that can cause damage a good distance from the tornado. Usually, the funnel cloud begins causing damage on the ground (becoming a tornado) within minutes of the RFD reaching the ground.
Cyclogenesis | Tornadoes
Whether it be a depression in the intertropical convergence zone (ITCZ), a tropical wave, a broad surface front, or an outflow boundary, a low level feature with sufficient vorticity and convergence is required to begin tropical cyclogenesis. Even with perfect upper level conditions and the required atmospheric instability, the lack of a surface focus will prevent the development of organized convection and a surface low. Tropical cyclones can form when smaller circulations within the Intertropical Convergence Zone merge.
Tropical cyclogenesis | Low level disturbance
The study of the atmosphere can be divided into distinct areas that depend on both time and spatial scales. At one extreme of this scale is climatology. In the timescales of hours to days, meteorology separates into micro-, meso-, and synoptic scale meteorology. Respectively, the geospatial size of each of these three scales relates directly with the appropriate timescale. Other subclassifications are used to describe the unique, local, or broad effects within those subclasses.
Meteorology | Spatial scales
Microscale meteorology is the study of short-lived atmospheric phenomena smaller than mesoscale, about 1 km or less. These two branches of meteorology are sometimes grouped together as "mesoscale and microscale meteorology" (MMM) and together study all phenomena smaller than synoptic scale; that is they study features generally too small to be depicted on a weather map. These include small and generally fleeting cloud "puffs" and other small cloud features.
Weather | Microscale meteorology
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 sustain a low pressure center, a preexisting low level focus or disturbance, and low vertical wind shear. While these conditions are necessary for tropical cyclone formation, they do not guarantee that a tropical cyclone will form.
Tropical cyclogenesis | Requirements for tropical cyclone formation
Extratropical cyclones form along linear bands of temperature/dewpoint gradient with significant vertical wind shear, and are thus classified as baroclinic cyclones. Initially, cyclogenesis, or low pressure formation, occurs along frontal zones near a favorable quadrant of a maximum in the upper level jetstream known as a jet streak. The favorable quadrants are usually at the right rear and left front quadrants, where divergence ensues. The divergence causes air to rush out from the top of the air column. As mass in the column is reduced, atmospheric pressure at surface level (the weight of the air column) is reduced. The lowered pressure strengthens the cyclone (a low pressure system).
Extratropical cyclone | Cyclogenesis
The following types of cyclones are identifiable in synoptic charts.
Cyclone | Synoptic scale
Mesoscale meteorology is the study of atmospheric phenomena that has horizontal scales ranging from 1 km to 1000 km and a vertical scale that starts at the Earth's surface and includes the atmospheric boundary layer, troposphere, tropopause, and the lower section of the stratosphere. Mesoscale timescales last from less than a day to weeks. The events typically of interest are thunderstorms, squall lines, fronts, precipitation bands in tropical and extratropical cyclones, and topographically generated weather systems such as mountain waves and sea and land breezes.
Meteorology | Mesoscale
Kerry Emanuel created a mathematical model around 1988 to compute the upper limit of tropical cyclone intensity based on sea surface temperature and atmospheric profiles from the latest global model runs. Emanuel's model is called the "maximum potential intensity", or MPI. Maps created from this equation show regions where tropical storm and hurricane formation is possible, based upon the thermodynamics of the atmosphere at the time of the last model run. This does not take into account vertical wind shear.
Tropical cyclogenesis | Role of Maximum Potential Intensity (MPI)
The synoptic scale metrology department deals with areas of remote sensing, using manual and automatic interpretation of satellite and radar data to make forecasts. In the field of numerical models, research focuses on the development of LAM Aladin, as in the new development of nowcasting model INCA.
Central Institution for Meteorology and Geodynamics | Synoptic scale and environmental metrology
The following types of cyclones are not identifiable in synoptic charts.
Cyclone | Mesoscale
Areas of precipitation help determine the frontal type and location. Mesoscale systems and boundaries such as tropical cyclones, outflow boundaries and squall lines are also analyzed on surface weather analyses. Isobars are commonly used to place surface boundaries from the horse latitudes poleward, while streamline analyses are used in the tropics.
Synoptic scale meteorology | Surface weather analysis
Discrete-event models, individual-based models, and agent-based models are special cases of microscale models. However, microscale models do not require discrete individuals or discrete events. Fine details on topography, buildings, and trees can add microscale detail to meteorological simulations and can connect to what are called mesoscale models in that discipline. Square-meter-sized landscape resolution available from images allow waterflow across land surfaces to be modeled, for example rivulets and water pockets, using gigabyte-sized arrays of detail. Models of neural networks may include individual neurons but may run in continuous time and thereby lack precise discrete events.
Microscale and macroscale models | Applications
Two of these storms reached tropical storm and subtropical storm intensity in August 2002 and September 2005 respectively.
Tropical cyclogenesis | Mediterranean and Black Seas
A minimum distance of from the equator (about 4.5 degrees from the equator) is normally needed for tropical cyclogenesis. The Coriolis force imparts rotation on the flow and arises as winds begin to flow in toward the lower pressure created by the pre-existing disturbance. In areas with a very small or non-existent Coriolis force (e.g. near the Equator), the only significant atmospheric forces in play are the "pressure gradient force" (the pressure difference that causes winds to blow from high to low pressure) and a smaller friction force; these two alone would not cause the large-scale rotation required for tropical cyclogenesis.
Tropical cyclogenesis | Coriolis force
A minimum distance of 500 km (300 mi) from the equator is normally needed for tropical cyclogenesis. Whether it be a depression in the Intertropical Convergence Zone (ITCZ) or monsoon trough, a broad surface front, or an outflow boundary, a low level feature with sufficient vorticity and convergence is required to begin tropical cyclogenesis. About 85 to 90 percent of Pacific typhoons form within the monsoon trough. Even with perfect upper-level conditions and the required atmospheric instability, the lack of a surface focus will prevent the development of organized convection and a surface low. Vertical wind shear of less than 10 m/s (20 kn, 33 ft/s) between the ocean surface and the tropopause is required for tropical cyclone development.
Typhoon | Genesis
Explosive cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, bomb cyclone or bombogenesis) is the rapid deepening of an 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 24 mbar (hPa) or more in 24 hours. This is a predominantly maritime, winter event, but also occurs in continental settings, even in the summer. This process is the extratropical equivalent of the tropical rapid deepening. Although their cyclogenesis is totally different from that of tropical cyclones, bomb cyclones can produce winds of 74–95 mph, the same order as the first categories of the Saffir-Simpson scale and give heavy precipitation.
Explosive cyclogenesis | Introduction
1. Holton, J. R. (2004). An introduction to dynamic meteorology. (4 ed., Vol. 88, pp. 269–276). San Diego, CA: Academic Press. 2. Hoskins, B. J., & Bretherton, F. P. (1972). Atmospheric frontogenesis models: Mathematical formulation and solution. J. Atmos. Sci., 29, 11-13. 3. Martin, J. E. (2006). Mid-latitude atmospheric dynamics. (1 ed., pp. 189–194). England: Wiley.
Frontogenesis | References
All of these effects are computed at each time-step in the study period and based not only on wind speed and elevation, but on quantities such as wind direction and thermodynamic properties of the lower atmosphere. This enables a sophisticated time-varying spatial analysis.
Time-varying microscale model | Introduction
In the physical sciences, spatial scale or simply scale refers to the order of magnitude of extent or size of a land area or geographical distance studied or described. For instance, in physics an object or phenomenon can be called microscopic if too small to be visible. In climatology, a micro-climate is a climate which might occur in a mountain, valley or near a lake shore. In statistics, a megatrend is a political, social, economical, environmental or technological trend which involves the whole planet or is supposed to last a very large amount of time. The concept is also used in geography, astronomy, and meteorology.
Spatial scale | Introduction
Meteorological & Geoastrophysical Abstracts is a scholarly bibliographic database that covers meteorology, climatology, atmospheric chemistry and physics, astrophysics, hydrology, glaciology, physical oceanography and environmental sciences.
Meteorological &amp; Geoastrophysical Abstracts | Introduction
Cyclostratigraphy is the study of astronomically forced climate cycles within sedimentary successions. Astronomical cycles are variations of the Earth's orbit around the sun due to the gravitational interaction with other masses within the solar system. Due to this cyclicity, solar irradiation differs through time on different hemispheres and seasonality is affected. These insolation variations have influence on Earth's climate and so on the deposition of sedimentary rocks. The main orbital cycles are precession with at present main periods of 19 and 23 kyr, obliquity with at present main periods of 41 kyr, and 1.2 Myr, and eccentricity with at present main periods of around 100 kyr, 405 kyr, and 2.4 Myr.
Cyclostratigraphy | Introduction
Measuring these transport processes involves use of micrometeorological (or flux) towers. Variables often measured or derived include net radiation, sensible heat flux, latent heat flux, ground heat storage, and fluxes of trace gases important to the atmosphere, biosphere, and hydrosphere. A micronet is an atmospheric and/or environmental observation network, composed of automated weather stations, used to monitor microscale phenomena. Micronets are sometimes considered a subtype of mesonet, and many micronets are a denser spatial resolution sub-network of a mesonet.
Microscale meteorology | Introduction
Areas within approximately ten degrees latitude of the equator do not experience a significant Coriolis Force, a vital ingredient in tropical cyclone formation. However, a few tropical cyclones have been observed forming within five degrees of the equator.
Tropical cyclogenesis | Near the Equator
Vertical wind shear of less than 10 m/s (20 kt, 22 mph) between the surface and the tropopause is favored for tropical cyclone development. A weaker vertical shear makes the storm grow faster vertically into the air, which helps the storm develop and become stronger. If the vertical shear is too strong, the storm cannot rise to its full potential and its energy becomes spread out over too large of an area for the storm to strengthen. Strong wind shear can "blow" the tropical cyclone apart, as it displaces the mid-level warm core from the surface circulation and dries out the mid-levels of the troposphere, halting development.
Tropical cyclogenesis | Weak vertical wind shear
Pressure differences in troposphere are "ΔP" = 10 Pa and density of air ρ = 10 kg·m. Other physical properties are approximately:
Scale analysis (mathematics) | Example: vertical momentum in synoptic-scale meteorology
The opposite of cyclogenesis is cyclolysis.
Cyclogenesis | Introduction
MCC is generally too small for synoptic scale measurements, but too large for single point measurements. However, satellite observations are able to monitor the development of the cloud patterns because of their large field of view. Satellites images from TIROS helped to highlight one of the main differences between laboratory convection cells and those that occur in the atmosphere. The ratio of the diameter of the hexagon compared to the depth of the cloud was much larger in the atmosphere compared to the same ratio calculated in controlled experiments. This difference showed that viscosity and heat conduction were important for the laboratory measurements, but eddy diffusion of heat and momentum dominated the atmospheric cells.
Remote sensing atmospheric boundary layer | Remote sensing of mesoscale cellular convection
A 2015 simulation of tropical cyclogenesis did not show increased tropical cyclone genesis in the Pliocene, although the simulation did not obtain a decreased East-West Pacific temperature gradient and it did obtain increased tropical cyclone activity in the parts of the Central Pacific most critical for the occurrence of Cyclonic Niño effects. A 2018 simulation implied that adding tropical cyclone mixing induced climate phenomena to simulations of mid-Piacenzian climate can in some aspects improve and in others reduce the match between the modelled climate and the climate reconstructed from paleoclimate data. A 2019 study concluded that tropical cyclone activity in the Western Pacific is correlated to El Niño-associated temperature anomalies months later.
Cyclonic Niño | Subsequent findings
ASOS and AWOS stations are typically spaced apart and report only hourly at many sites. The Cooperative Observer Program (COOP) database consists of only daily reports. "Mesoscale" weather phenomena occur on spatial scales of tens to hundreds of kilometers and temporal (time) scales of minutes to hours. Thus, an observing network with finer temporal and spatial scales is needed for mesoscale research. This need led to the development of the mesonet. Mesonet data is directly used by humans for decision making, but also boosts the skill of numerical weather prediction and is especially beneficial for short-range mesoscale models. Mesonets, along with remote sensing solutions (data assimilation of weather radar, weather satellites, wind profilers), allow for much greater temporal and spatial resolution in a forecast model.
Mesonet | Purpose
Cyclones have also been seen on extraterrestrial planets, such as Mars, Jupiter, and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become 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 subtropical jet stream. Weather fronts mark the boundary between two masses of air of different temperature, humidity, and densities, and are associated with the most prominent meteorological phenomena.
Cyclone | Introduction
It has also been noted that when the monsoon trough lies near 20 degrees north latitude in the Pacific, the frequency of tropical cyclones is 2 to 3 times greater than when it lies closer to 10 degrees north.
Monsoon trough | In tropical cyclogenesis
Since 1984, Colorado State University has been issuing seasonal tropical cyclone forecasts for the north Atlantic basin, with results that are better than climatology. The university has found several statistical relationships for this basin that appear to allow long range prediction of the number of tropical cyclones. Since then, numerous others have followed in the university's steps, with some organizations issuing seasonal forecasts for the northwest Pacific and the Australian region. The predictors are related to regional oscillations in the global climate system: the Walker circulation which is related to the El Niño-Southern Oscillation; the North Atlantic oscillation (NAO); the Arctic oscillation (AO); and the Pacific North American pattern (PNA).
Tropical cyclogenesis | Seasonal forecasts
A majority of Mediterranean tropical cyclones (tropical cyclogenesis) form over two separate regions. The first, more conducive for development than the other, encompasses an area of the western Mediterranean bordered by the Balearic Islands, southern France, and the shorelines of the islands of Corsica and Sardinia. The second identified region of development, in the Ionian Sea between Sicily and Greece and stretching south to Libya, is less favorable for tropical cyclogenesis. An additional two regions, in the Aegean and Adriatic seas, produce fewer medicanes, while activity is minimal in the Levantine region. The geographical distribution of Mediterranean tropical-like cyclones is markedly different from that of other cyclones, with the formation of regular cyclones centering on the Pyrenees and Atlas mountain ranges, the Gulf of Genoa, and the island of Cyprus in the Ionian Sea.
Mediterranean tropical-like cyclone | Climatology
Tropical cyclogenesis in the Northwestern Pacific is suppressed west of 150°E in the year following an El Niño event.
Tropical cyclogenesis | Influence of ENSO
Areas farther than 30 degrees from the equator (except in the vicinity of a warm current) are not normally conducive to tropical cyclone formation or strengthening, and areas more than 40 degrees from the equator are often very hostile to such development. The primary limiting factor is water temperatures, although higher shear at increasing latitudes is also a factor. These areas are sometimes frequented by cyclones moving poleward from tropical latitudes. On rare occasions, such as Pablo in 2019, Alex in 2004, Alberto in 1988, and the 1975 Pacific Northwest hurricane, storms may form or strengthen in this region. Typically, tropical cyclones will undergo extratropical transition after recurving polewards, and typically become fully extratropical after reaching 45–50˚ of latitude.
Tropical cyclogenesis | Middle latitudes
Cyclogenesis can only occur when temperature decreases polewards (to the north, in the northern hemisphere), and pressure perturbation lines tilt westward with height. Cyclogenesis is most likely to occur in regions of cyclonic vorticity advection, downstream of a strong westerly jet. The combination of vorticity advection and thermal advection created by the temperature gradient and a low pressure center cause upward motion around the low. If the temperature gradient is strong enough, temperature advection will increase, driving more vertical motion. This increases the overall strength of the system. Shearwise updrafts are the most important factor in determining cyclonic growth and strength.
Cyclogenesis | Vertical motion affecting development
A recent example of a tropical cyclone that maintained itself over cooler waters was Epsilon of the 2005 Atlantic hurricane season.
Tropical cyclogenesis | Warm waters, instability, and mid-level moisture
Eventually, the cyclone will become barotropically cold and begin to weaken. Atmospheric pressure can fall very rapidly when there are strong upper level forces on the system. When pressures fall more than per hour, the process is called explosive cyclogenesis, and the cyclone can be described as a bomb. These bombs rapidly drop in pressure to below under favorable conditions such as near a natural temperature gradient like the Gulf Stream, or at a preferred quadrant of an upper-level jet streak, where upper level divergence is best. The stronger the upper level divergence over the cyclone, the deeper the cyclone can become.
Extratropical cyclone | Cyclogenesis
An inverse relationship exists between tropical cyclone activity in the western north Pacific basin and the north Atlantic basin, however. When one basin is active, the other is normally quiet, and vice versa. The main reason for this appears to be the phase of the MJO, which is normally in opposite modes between the two basins at any given time. While this relationship appears robust, the MJO is one of many factors that contribute to the development of tropical cyclones. For example, sea surface temperatures must be sufficiently warm and vertical wind shear must be sufficiently weak for tropical disturbances to form and persist.
Madden–Julian oscillation | Influence on tropical cyclogenesis
The data are assumed to be reset to their initial values on each invocation of formula_16." Figure 3. "Graphical comparison of the dynamics of macroscale and microscale simulations of Figures 1 and 2, respectively."
Microscale and macroscale models | Figures
The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the thermal decomposition of trimethylcyclopropylammonium hydroxide over platinized clay at 320–330 °C under a CO atmosphere. This reaction produces mainly trimethylamine and dimethylcyclopropyl amine, together with about 5% of cyclopropene. Cyclopropene can also be obtained in about 1% yield by thermolysis of the adduct of cycloheptatriene and dimethyl acetylenedicarboxylate.
Cyclopropene | Early syntheses
A case study of the Manual of Synoptic Satellite Meteorology featured by the Austrian Meteorological Institute (ZAMG) identified an area of secondary cyclogenesis which brought gusts in excess of 90 km/h to Northern France, Belgium and Southwestern Germany. The system formed in the wake of Lothar, and crossed Europe before the arrival of the later Cyclone Martin. The identification of this secondary area and its frontal systems contrasts with the analysis of the German Weather Service which suggested that solely a 'trough line' crossed Germany.
Cyclone Lothar | Lothar successor
As Kohler and Reed put it, Korotayev and Turchin have demonstrated that "human population movements and sociopolitical strife play the roles of sometimes endogenous, sometimes exogenous, factors that on small spatial scales may seem inexplicable but which on longer temporal and wider spatial scales may have understandable rhythms".
Andrey Korotayev | Cliodynamics and the study of the Arab Spring
For these reasons, only the frequency of storms can be reliably estimated from tree ring isotopic records, not their intensity. Speleothems, deposits formed in caves through the dissolution and redeposition of dolomite and limestone, can store isotope signatures associated with tropical cyclones, especially in fast growing speleothems, areas with thin soils and speleothems which have undergone little alteration. Such deposits have a high temporal resolution, and are also protected from many confounding factors although the extraction of annual layers has become possible only recently, with a two-week resolution (two separate layers correlated to two hurricanes that struck two weeks apart) achieved in one case.
Paleotempestology | Isotope ratios
The database is produced by the American Meteorological Society, and is published by DIALOG and Cambridge Scientific Abstracts.
Meteorological &amp; Geoastrophysical Abstracts | Production and Access
There are several forms of mesoscale meteorology, including simplistic isolated thunderstorms unrelated to advancing cold fronts, to the more complex daytime/nocturnal Mesoscale Convective System (MCS) and Mesoscale Convective Complex (MCC), to squall line thunderstorms.
Squall | Squall line life cycle
Tropical cyclones are known to form even when normal conditions are not met. For example, cooler air temperatures at a higher altitude (e.g., at the 500 hPa level, or 5.9 km) can lead to tropical cyclogenesis at lower water temperatures, as a certain lapse rate is required to force the atmosphere to be unstable enough for convection. In a moist atmosphere, this lapse rate is 6.5 °C/km, while in an atmosphere with less than 100% relative humidity, the required lapse rate is 9.8 °C/km. At the 500 hPa level, the air temperature averages −7 °C (18 °F) within the tropics, but air in the tropics is normally dry at this height, giving the air room to wet-bulb, or cool as it moistens, to a more favorable temperature that can then support convection.
Sea surface temperature | Tropical cyclones
Simulations using the CESM climate model conducted in 2018 showed a reduced temperature gradient between the East and West Pacific and a deeper thermocline in response to tropical cyclone driven mixing and anomalous eastward sea currents in the Pacific; this is accompanied by a cooling of the areas where mixing is strongest and a warming of the Eastern Pacific. There are also effects on the East Asian monsoon such as a stronger winter monsoon but in the simulations the background climate of the Piacenzian was more significant than the tropical cyclone effects.
Cyclonic Niño | Computer simulations concerning the Pliocene
A synoptic scale feature is one whose dimensions are large in scale, more than several hundred kilometers in length. Migratory pressure systems and frontal zones exist on this scale.
Surface weather analysis | Synoptic scale features
The Renaissance brought significant development of instruments to measure atmospheric phenomena and scales to compare them. Subsequent developments in atmospheric science in the 18th Century confirmed the need for widespread measurement and uniform transnational measurement scales. In the early 19th Century countries began to share meteorological data, and on this basis a conference was held in Cambridge in 1845 with representation by the leading British and European meteorologists, including: Matthew Fontaine Maury, of the US Navy, initiated the convening of the first true International Meteorological conference from late August through early September 1853. The Conference opened its proceedings at Brussels, Belgium, on the 23d August 1853, in the residence of M.
International Meteorological Organization | History
Mammal zones were, like all biozones, established using geographic place names where fossil materials were obtained. The basic unit of measure is the first/last boundary statement. This shows that the first appearance event of one taxon is known to predate the last appearance event of another. If two taxa are found in the same fossil quarry or at the same stratigraphic horizon, then their age-range zones overlap. The terrestrial stratigraphy of the Cenozoic is more difficult than that of marine deposits. The geologic timescale of the ICS is therefore based on marine fossils, that don't occur in terrestrial sediments. This makes the correlation of terrestrial deposits with the ICS timescale often difficult.
European land mammal age | Biostratigraphic methods
The April 1960 launch of the first successful weather satellite, TIROS-1, marked the beginning of the age where weather information became available globally.
Meteorology | Instruments and classification scales
Consider for example the momentum equation of the Navier–Stokes equations in the vertical coordinate direction of the atmosphere where "R" is Earth radius, Ω is frequency of rotation of the Earth, "g" is gravitational acceleration, φ is latitude, ρ is density of air and ν is kinematic viscosity of air (we can neglect turbulence in free atmosphere). In synoptic scale we can expect horizontal velocities about "U" = 10 m.s and vertical about "W" = 10 m.s. Horizontal scale is "L" = 10 m and vertical scale is "H" = 10 m. Typical time scale is "T" = "L"/"U" = 10 s.
Scale analysis (mathematics) | Example: vertical momentum in synoptic-scale meteorology
Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear. Cyclolysis is the opposite of cyclogenesis, and is the high-pressure system equivalent, which deals with the formation of high-pressure areas—Anticyclogenesis.
Cyclone | Formation
The horizontal shear and horizontal deformation direct to concentrate the pole-equator temperature gradient over a large synoptic scale (1000 km). The quasi-geostrophic equations fail in the dynamics of frontogenesis because this weather phenomenon is of smaller scale compared to the Rossby radius; so semigeostrophic theory is used. Generally, Rossby number—ratio of inertial to coriolis terms—is used to formulate a condition of geostrophic flow. Across the front, the Rossby number is on the order of udu/dx/fv = (10 m/s)^2/(1000 km)/(1e-4 s-1)/(1 m/s) = 1; this shows we cannot ignore the inertial term (one must take into account the ageostrophic wind). Along the front, the Rossby number is on the order of udv/dx/fu = (10 m/s)/(1000 km)*(1e-4 s-1)*(10 m/s) = 0.01, which means it is in geostrophic and thermal wind balance.
Frontogenesis | Elements of Frontogenesis
Beginning in the late 1840s, the Smithsonian Institution became the first organization to draw real-time surface analyses. Use of surface analyses began first in the United States, spreading worldwide during the 1870s. Use of the Norwegian cyclone model for frontal analysis began in the late 1910s across Europe, with its use finally spreading to the United States during World War II. Surface weather analyses have special symbols which show frontal systems, cloud cover, precipitation, or other important information. For example, an "H" represents high pressure, implying good and fair weather. An "L" represents low pressure, which frequently accompanies precipitation. Various symbols are used not just for frontal zones and other surface boundaries on weather maps, but also to depict the present weather at various locations on the weather map.
Synoptic scale meteorology | Surface weather analysis
The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. The exine is what is preserved in the fossil record. Two basic types of microsporogenesis are recognised, simultaneous and successive. In simultaneous microsporogenesis meiotic steps I and II are completed before cytokinesis, whereas in successive microsporogenesis cytokinesis follows. While there may be a continuum with intermediate forms, the type of microsporogenesis has systematic significance. The predominant form amongst the monocots is successive, but there are important exceptions.
Pollen | Formation
Numerical Weather Prediction is a main focus in understanding air–sea interaction, tropical meteorology, atmospheric predictability, and tropospheric/stratospheric processes. The Naval Research Laboratory in Monterey, California, developed a global atmospheric model called Navy Operational Global Atmospheric Prediction System (NOGAPS). NOGAPS is run operationally at Fleet Numerical Meteorology and Oceanography Center for the United States Military. Many other global atmospheric models are run by national meteorological agencies.
Meteorology | Global scale
This effect can take up to a century to set in and its strength is dependent on the exact pattern of ocean mixing. It is also subject to positive feedback, as the warming of the eastern Pacific in turn increases tropical cyclone activity; eventually a climate state featuring a permanent El Niño and a weaker El Niño Southern Oscillation can arise. During the mid-Piacenzian where carbon dioxide concentrations were close to present-day levels, Earth was about warmer than present and simulations indicate that tropical cyclones were more intense; the modelled distribution of tropical cyclones however was different from the one reconstructed for other stages of the Pliocene.
Cyclonic Niño | Computer simulations concerning the Pliocene
The Cooperative Institute for Mesoscale Meteorological Studies is a research organization created in 1978 by a cooperative agreement between the University of Oklahoma (OU) and the National Oceanic and Atmospheric Administration (NOAA). CIMMS promotes collaborative research between NOAA and OU scientists on problems of mutual interest to improve basic understanding of mesoscale meteorological phenomena, weather radar, and regional climate to help produce better forecasts and warnings that save lives and property. CIMMS research contributes to the NOAA mission through improvement of the observation, analysis, understanding, and prediction of weather elements and systems and climate anomalies ranging in size from cloud nuclei to multi-state areas.
Cooperative Institute for Mesoscale Meteorological Studies | Introduction
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. 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 (a trough of warm air aloft). All developing low pressure areas share one important aspect, that of upward vertical motion within the troposphere.
Cyclogenesis | Modes of development
In biology, the BBCH-scale for peas describes the phenological development of peas using the BBCH-scale. The phenological growth stages and BBCH-identification keys of peas are: 1 The first internode extends from the scale leaf node to the first true leaf node
BBCH-scale (pea) | Introduction
Subsequent to the first extinctions, excursions in the δC and δO records are observed; δC rises from +1.4‰ to +4.5‰, while δO increases from −5.6‰ to −5.0‰.
Telychian | Geochemistry
On the first approximation listed above—that birth and death rates are constant—the macroscale model of the Figure 1 is exactly the mean of a large number of stochastic trials with the growth rate fluctuating randomly in each instance of time. Microscale stochastic details are subsumed into a partial differential diffusion equation and that equation is used to establish the equivalence.
Microscale and macroscale models | Example