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Col (meteorology)
A col, also called saddle point or neutral point, is in meteorology, the point of intersection of a Trough (meteorology), trough and a Ridge (meteorology), ridge in the pressure pattern of a weather map. It takes the form of a saddle where the air pressure is relatively higher than that of the low-pressure regions, but lower than that of the anticyclonic zones. In a barometric col, the winds are relatively calm and varying in direction. The weather is also unsettle and favorable for winter fog or summer storms due to the accumulation of moisture in the air mass due to lack of ventilation. It is thus often the position of a stationary or quasi-stationary front. Description In a weather map as the one to the right, a col is a region where the position of highs (H) and lows (L) produces a Convergence zone, convergence or divergence of the airflow; this includes 2 juxtaposed highs and 2 juxtaposed lows. This pattern packs Isotherm (contour line), isotherms and moisture: warm air is ad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure without a closed isobaric contour that would define it as a low pressure area. Since low pressure implies a low height on a pressure surface, troughs and ridges refer to features in an identical sense as those on a topographic map. Troughs may be at the surface, or aloft. Near-surface troughs sometimes mark a weather front associated with clouds, showers, and a wind direction shift. Upper-level troughs in the jet stream (as shown in diagram) reflect cyclonic filaments of vorticity. Their motion induces upper-level wind divergence, lifting and cooling the air ahead (downstream) of the trough and helping to produce cloudy and rain conditions there. Unlike fronts, there is not a universal symbol for a trough on a surface weather analysis chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked as a dashed line or bold line. In the UK, Hong Kong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ridge (meteorology)
A ridge or barometric ridge is a term in meteorology describing an elongated area of relatively high atmospheric pressure compared to the surrounding environment, without being a closed circulation. It is associated with an area of maximum anticyclonic curvature of wind flow. The ridge originates in the center of an anticyclone and sandwiched between two low-pressure areas, and the locus of the maximum curvature is called the ''ridge line''. This phenomenon is the opposite of a trough. Description Ridges can be represented in two ways: * On surface weather maps, the pressure isobars form contours where the maximum pressure is found along the axis of the ridge. * In upper-air maps, geopotential height isohypses form similar contours where the maximum defines the ridge. Related weather Given the direction of the winds around an anticyclonic circulation and the fact that weather systems move from west to east: *ahead of an upper-ridge, the airflow that comes from the polar regi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Map
A weather map, also known as synoptic weather chart, displays various meteorological features across a particular area at a particular point in time and has various symbols which all have specific meanings. Such maps have been in use since the mid-19th century and are used for research and weather forecasting purposes. Maps using isotherms show temperature gradients, which can help locate weather fronts. Isotach maps, analyzing lines of equal wind speed, on a constant pressure surface of 300 or 250 hPa show where the jet stream is located. Use of constant pressure charts at the 700 and 500 hPa level can indicate tropical cyclone motion. Two-dimensional streamlines based on wind speeds at various levels show areas of convergence and divergence in the wind field, which are helpful in determining the location of features within the wind pattern. A popular type of surface weather map is the surface weather analysis, which plots isobars to depict areas of high pressure and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saddle
The saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not known precisely when riders first began to use some sort of padding or protection, but a blanket attached by some form of surcingle or girth was probably the first "saddle", followed later by more elaborate padded designs. The solid saddle tree was a later invention, and though early stirrup designs predated the invention of the solid tree, the paired stirrup, which attached to the tree, was the last element of the saddle to reach the basic form that is still used today. Today, modern saddles come in a wide variety of styles, each designed for a specific equestrianism discipline, and require careful fit to both the rider and the horse. Proper saddle care can extend the useful life of a saddle, often for decades. The saddle was a crucial step ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Meteorological Society
The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the Atmospheric sciences, atmospheric, Oceanography, oceanic, and Hydrology, hydrologic sciences. Its mission is to advance the atmospheric and related sciences, technologies, applications, and services for the benefit of society. Background Founded on December 29, 1919, by Charles Franklin Brooks at a meeting of the American Association for the Advancement of Science in St. Louis and incorporated on January 21, 1920, the American Meteorological Society has a membership of more than 13,000 weather, water, and climate scientists, professionals, researchers, educators, students, and enthusiasts. AMS offers numerous programs and services in the sphere of water, weather and climate sciences. It publishes eleven atmospheric and related oceanic and hydrologic journals (in print and online), sponsors as many as twelve conf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Mass
In meteorology, an air mass is a volume of air defined by its temperature and humidity. Air masses cover many hundreds or thousands of square miles, and adapt to 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 or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry, while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density (temperature or moisture) characteristics. Once an air mass moves away from its source region, underlying vegetation and body of water, water bodies can quickly modify its character. Classification schemes tackle an air mass' characteristics, as well as modification. Classification and notation The Tor Bergeron, Bergeron classification is the most widely accepted form of air mass classification, though others have produced more refined versions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergence Zone
A convergence zone in meteorology is a region in the atmosphere where two prevailing flows meet and interact, usually resulting in distinctive weather conditions. This causes a mass accumulation that eventually leads to a vertical movement and to the formation of clouds and precipitation. Large-scale convergence, called synoptic-scale convergence, is associated with weather systems such as baroclinic troughs, low-pressure areas, and cyclones. The large-scale convergence zone formed over the equator, the Intertropical Convergence Zone, has condensed and intensified as a result of the global increase in temperature. Small-scale convergence will give phenomena from isolated cumulus clouds to large areas of thunderstorms. The inverse of convergence is divergence. Large scale An example of a convergence zone is the Intertropical Convergence Zone (ITCZ), a low pressure area which girdles the Earth at the Equator.Waliser, D.E.; Jiang, X. (2015). "Tropical Meteorology and Climate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Divergence
In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the quantity of the vector field's source at each point. More technically, the divergence represents the volume density of the outward flux of a vector field from an infinitesimal volume around a given point. As an example, consider air as it is heated or cooled. The velocity of the air at each point defines a vector field. While air is heated in a region, it expands in all directions, and thus the velocity field points outward from that region. The divergence of the velocity field in that region would thus have a positive value. While the air is cooled and thus contracting, the divergence of the velocity has a negative value. Physical interpretation of divergence In physical terms, the divergence of a vector field is the extent to which the vector field flux behaves like a source at a given point. It is a local measure of its "outgoingness" – the extent to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotherm (contour Line)
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function f(x,y) parallel to the (x,y)-plane. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value. In cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines. The gradient of the function is always perpendicular to the contour lines. When the lines are close together the magnitude of the gradie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stationary Front
A stationary front (or quasi-stationary front) is a weather front or transition zone between two air masses when both air mass is advancing into the other at speeds exceeding 5 knots (about 6 miles per hour or about 9 kilometers per hour) at the ground surface. On weather maps, it's illustrated as a solid line of alternating blue spikes pointing to the warmer air mass and red domes facing the colder air mass. Development A stationary front may form when a cold or warm front slows down or grows over time from underlying surface temperature differences, like a coastal front. Winds on the cold air and warm air sides often flow nearly parallel to the stationary front, often in opposite directions along either side of the stationary front. A stationary front usually remains in the same area for hours to days and may undulate as atmospheric waves move eastward along the front. Stationary fronts may also change into a cold or warm front and may form one or more extratropical or mid-latit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (meteorology)
Deformation is the rate of change of shape of fluid bodies. Meteorologically, this quantity is very important in the formation of atmospheric fronts, in the explanation of cloud shapes, and in the diffusion of materials and properties.Djurić, D: "Weather Analysis". Prentice Hall, 1994. . Equations The deformation of horizontal wind is defined as \operatorname \mathbf = \sqrt, where \ A = \frac + \frac and \ B = \frac - \frac, representing the derivatives of wind component. Because these derivatives vary greatly with the rotation of the coordinate system, so do \ A and \ B. Stretching direction The deformation elements \ A and \ B (above) can be used to find the ''direction of the dilatation axis'', the line along which the material elements stretch (also known as the ''stretching direction''). Several flow patterns are characteristic of large deformation: confluence, diffluence, and shear flow. , also known as ''stretching'', is the elongating of a fluid body along the flow ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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