Related Research Articles
Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations.
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 characteristics. Once an air mass moves away from its source region, underlying vegetation and water bodies can quickly modify its character. Classification schemes tackle an air mass's characteristics, as well as modification.
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation.
In meteorology, the synoptic scale is a horizontal length scale of the order of 1,000 km (620 mi) or more. This corresponds to a horizontal scale typical of mid-latitude depressions. Most high- and low-pressure areas seen on weather maps 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. Most precipitation areas occur near frontal zones. The word synoptic is derived from the Ancient Greek word συνοπτικός (sunoptikós), meaning "seen together".
A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient. Warm fronts lie within broader troughs of low pressure than cold fronts, and move more slowly than the cold fronts which usually follow because cold air is denser and less easy to remove from the Earth's surface. This also forces temperature differences across warm fronts to be broader in scale. Clouds ahead of the warm front are mostly stratiform, and rainfall defiantly increases as the front approaches. Fog can also occur preceding a warm frontal passage. Clearing and warming is usually rapid after frontal passage. If the warm air mass is unstable, thunderstorms may be embedded among the stratiform clouds ahead of the front, and after frontal passage thundershowers may continue. On weather maps, the surface location of a warm front is marked with a red line of semicircles pointing in the direction of travel.
A stationary front is a weather front or transition zone between two air masses when each air mass is advancing into the other at speeds exceeding 5 knots at the ground surface. On weather maps, it is illustrated as a solid line of alternating blue spikes pointing to the warmer air mass and red domes facing the colder air mass.
In meteorology, an occluded front is a type of weather front formed during cyclogenesis. The classical and usual view of an occluded front is that it starts when a cold front overtakes a warm front near a cyclone, such that the warm air is separated (occluded) from the cyclone center at the surface. The point where the warm front becomes the occluded front is the triple point; a new area of low-pressure that develops at this point is called a triple-point low. A more modern view of the formation process suggests that occluded fronts form directly without the influence of other fronts during the wrap-up of the baroclinic zone during cyclogenesis, and then lengthen due to flow deformation and rotation around the cyclone as the cyclone forms.
A stationary bicycle is a device used as exercise equipment for indoor cycling. It includes a saddle, pedals, and some form of handlebars arranged as on a (stationary) bicycle.
In meteorology, training denotes repeated areas of rain, typically associated with thunderstorms, that move over the same region in a relatively short period of time. Training thunderstorms are capable of producing excessive rainfall totals, often causing flash flooding. The name training is derived from how a train and its cars travel along a track, without the track moving.
In meteorology, the polar highs are areas of high atmospheric pressure, sometimes similar to anticyclones, around the north and south poles; the south polar high being the stronger one because land gains and loses heat more effectively than sea, which the north has much less of. The cold temperatures in the polar regions cause air to descend, creating the high pressure, just as the warm temperatures around the equator cause air to rise instead and create the low pressure intertropical convergence zone. Rising air also occurs along bands of low pressure situated just below the polar highs around the 50th parallel of latitude. These extratropical convergence zones are occupied by the polar fronts where air masses of polar origin meet and clash with those of tropical or subtropical origin in a stationary front. This convergence of rising air completes the vertical cycle around the polar cell in each latitudinal hemisphere's polar region. Closely related to this concept is the polar vortex, a rotating low-pressure circle of cold air around the poles.
A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For instance, cold fronts can bring bands of thunderstorms and cumulonimbus precipitation or be preceded by squall lines, while warm fronts are usually preceded by stratiform precipitation and fog. In summer, subtler humidity gradients known as dry lines can trigger severe weather. Some fronts produce no precipitation and little cloudiness, although there is invariably a wind shift.
In meteorology, the polar front is the weather front boundary between the polar cell and the Ferrel cell around the 60° latitude, near the polar regions, in both hemispheres. At this boundary a sharp gradient in temperature occurs between these two air masses, each at very different temperatures.
Ice pellets or sleet is a form of precipitation consisting of small, hard, translucent balls of ice. Ice pellets are different from graupel, which is made of frosty white opaque rime, and from a mixture of rain and snow, which is a slushy liquid or semisolid. Ice pellets often bounce when they hit the ground or other solid objects, and make a higher-pitched "tap" when striking objects like jackets, windshields, and dried leaves, compared to the dull splat of liquid raindrops. Pellets generally do not freeze into other solid masses unless mixed with freezing rain. The METAR code for ice pellets is PL.
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of producing anything from cloudiness and mild showers to severe gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale (synoptic) low pressure weather systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, about the center of the cyclone.
In meteorology, a pseudo-cold front is a boundary between a supercell's inflow region and the rear flank downdraft. It usually extends outward from a mesocyclone center, usually toward the south or southwest, and is characterized by advancing of the downdraft air toward the inflow region. It is a particular form of gust front.
A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone, at the leading edge of its cold air advection pattern—known as the cyclone's dry "conveyor belt" flow. Temperature differences across the boundary can exceed 30 °C (54 °F) from one side to the other. When enough moisture is present, rain can occur along the boundary. If there is significant instability along the boundary, a narrow line of thunderstorms can form along the frontal zone. If instability is weak, a broad shield of rain can move in behind the front, and evaporative cooling of the rain can increase the temperature difference across the front. Cold fronts are stronger in the fall and spring transition seasons and are weakest during the summer.
A col, also called saddle point or neutral point, is in meteorology, the point of intersection of a trough and a 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.
The meiyu front, also known as baiu front, is a persistent nearly stationary weak baroclinic zone in the lower troposphere. It is located over the east coast of China and Taiwan at its western end, and over the Pacific Ocean south of Japan at its eastern end.
Trilateration is the use of distances for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning). When more than three distances are involved, it may be called multilateration, for emphasis.
The Australian High, also known as the Australian subtropical ridge, is a large, semi-permanent high pressure area or subtropical anticyclone that seasonally vacillates between the Great Australian Bight in the south to the Northern Territory in the north. It is generally located between 25 and 40 degrees of south latitude, depending on the season.
References
- ↑ Branick, Michael. "A Comprehensive Glossary of Weather" . Retrieved 2007-05-28.
 | This meteorology–related article is a stub. You can help Wikipedia by expanding it. |