Diferencia entre revisiones de «Frente de ráfaga»

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[[archivo:Thunderstorm with lead gust front - NOAA.jpg|thumb|right|250 px|Tormenta con pesado frente, Brookhaven, New Mexico]]
Un flujo del tipo frente de ráfaga, o nube de arco, es el principio de los vientos en ráfagas, más fríos, de tormentas con [[ascendente (meteoro)|ascendente]]s; a veces asociados con una [[nube en arco]]. Un súbito salto en la presión es asociado con su pasaje.<ref>{{cite web|publisher=[[American Meteorological Society]]|author=Glossary of Meteorology|date=2009|accessdate=3 de julio 2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=gust+front&submit=Search|title=Gust Front}}</ref> Y pueden persistir por más de 24 [[hora|h]] y atravesar centenares de miles de [[km]] desde su área de origen.<ref>{{cite web|author=[[National Weather Service]]|date=1 de noviembre 2004|url=http://www.weather.gov/glossary/index.php?word=OUTFLOW%20Boundary|title=Outflow Boundary|accessdate=9 de julio 2008}}</ref> <!--A wrapping gust front is a front that wraps around the [[mesocyclone]], cutting off the inflow of warm moist air and resulting in occlusion. This is sometimes the case during the event of a collapsing storm, in which the wind literally "rips it apart".<ref>{{cite web|author=[[National Weather Service]]|url=http://www.weather.gov/glossary/index.php?word=Wrapping+gust+front|title=Wrapping Gust Front|accessdate=3 de julio 2009|date=1 de noviembre 2004}}</ref>
[[archivo:Microburstnasa.JPG|250px|thumb|right|IllustrationIlustración ofde aun microburstmicrofrente. TheEl windrégimen regimeventoso inen ael microburstmicrofrente ises oppositeopuesto toal thatde of aun tornado.]]<!--
{{See also|Downburst|Squall line}}
A [[microburst]] is a very localized column of sinking air known as a downburst, producing damaging divergent and [[straight-line winds]] at the surface that are similar to but distinguishable from [[tornado]]es which generally have convergent damage.<ref>{{cite web|author=Dr. Nolan Atkins|date=2009|publisher=[[Lyndon State College]] Meteorology|url=http://apollo.lsc.vsc.edu/classes/met130/notes/chapter14/tornado_mb_damage.html|title=How to distinguish between tornado and microburst (straight-line) wind damage|accessdate=2008-07-09}}</ref> The term was defined as affecting an area {{convert|4|km|mi}} in diameter or less,<ref>{{cite web|author=[[National Weather Association]]|date=2003-11-23 de noviembre 2003|url=http://www.nwas.org/committees/avnwxcourse/lesson5.htm|title=Welcome to Lesson 5|accessdate=2008-07-09}}</ref> distinguishing them as a type of downburst and apart from common wind shear which can encompass greater areas. They are normally associated with individual thunderstorms. Microburst soundings show the presence of mid-level dry air, which enhances evaporative cooling.<ref name="micro">{{cite web|author=Fernando Caracena, Ronald L. Holle, and Charles A. Doswell III|date=26 de junio 2002|publisher=Cooperative Institute for Mesoscale Meteorological Studies|url=http://www.cimms.ou.edu/~doswell/microbursts/Handbook.html|title=Microbursts: A Handbook for Visual Identification|accessdate=9 de julio 2008}}</ref>
Organized areas of thunderstorm activity reinforce pre-existing frontal zones, and can outrun cold fronts. This outrunning occurs within the [[westerlies]] in a pattern where the upper level jet splits into two streams. The resultant [[Mesoscale Convective System|mesoscale convective system]] (MCS) forms at the point of the upper level split in the wind pattern in the area of best low level inflow. The convection then moves east and toward the [[equator]] into the warm sector, parallel to low-level thickness lines. When the convection is strong and linear or curved, the MCS is called a [[squall line]], with the feature placed at the leading edge of the significant wind shift and pressure rise which is normally just ahead of its radar signature.<ref>{{cite web|author=Office of the Federal Coordinator for Meteorology|date=2008|url=http://www.ofcm.gov/slso/pdf/slsochp2.pdf|title=Chapter 2: Definitions|page=2-1|publisher=[[NOAA]]|accessdate=2009-05-03}}</ref> This feature is commonly depicted in the warm season across the [[United States]] on surface analyses, as they lie within sharp surface troughs.
==Appearance Apariencia ==
[[Filearchivo:DangerousShelfCloud.jpg|thumb|right|250 px|ThisNube shelfde cloud preceded a [[derecho]] infrente, [[Minnesota]]]]<!--
At ground level, [[shelf cloud]]s and [[roll cloud]]s can be seen at the leading edge of outflow boundaries.<ref>{{cite web|url=http://www.met.utah.edu/class/jhorel/5140/radar_handbook.pdf|title=Federal Meteorological Handbook No. 11 Doppler RADAR Meteorological Observations Part B Doppler RADAR Theory and Meteorology|author=Office of the Federal Coordinator For
Meteorological Services and Supporting Research|publisher=[[Department of Commerce]]|date=December 2005|accessdate=2009-09-01}}</ref> Through [[weather satellite|satellite]] imagery, an arc cloud is visible as an arc of low clouds spreading out from a thunderstorm. If the skies are cloudy behind the arc, or if the arc is moving quickly indicate that high wind gusts are likely behind the gust front.<ref>{{cite book|url=http://books.google.com/books?id=o2wfF7xNqGYC&pg=PA322&lpg=PA322&dq=satellite+arc+cloud+outflow+boundary+book&source=bl&ots=nIBpVqGJw5&sig=n7cafZP3T7-tKw3PcR43TDH3keU&hl=en&ei=d7OdSoH-G86w8QanycG4Aw&sa=X&oi=book_result&ct=result&resnum=2#v=onepage&q=&f=false|author=Pravas Mahapatra, R. J. Doviak, Vladislav Mazur, Dušan S. Zrnić|title=Aviation weather surveillance systems: advanced radar and surface sensors for flight safety and air traffic management, Volume 183|page=322|year=1999|publisher=Institution of Electrical Engineers|ISBN=9780852969373|accessdate=2009-09-01}}</ref> Sometimes a gust front can be seen on [[weather radar]], showing as a thin arc or line of weak radar echos pushing out from a collapsing storm. The thin line of weak radar echoes is known as a fine line.<ref>{{cite web|author=Glossary of Meteorology|date=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=fine+line&submit=Search|title=Fine Line|publisher=[[American Meteorological Society]]|accessdate=2009-07-03}}</ref> Occasionally, winds caused by the gust front are so high in velocity, that they may also show up on radar. This cool outdraft can then energize other storms which it hits by assisting in [[updraft]]s. Gust fronts colliding from two storms can even create new storms. However, there is usually no rain accompanying the shifting winds. An expansion of the rain shaft near ground level, in the general shape of a foot, is a telltale sign of a downburst. Gustnadoes, short-lived vertical circulations near ground level, can be spawned by outflow boundaries.<ref name="micro"/>
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