Cold front
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2008-07-09T16:59:30Z
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{{for|the Star Trek: Enterprise episode|Cold Front (Enterprise)}}
[[Image:Cold front symbol.svg|thumb|right|The symbol of a cold front: a blue line with triangles pointing in the direction of travel]]
A '''cold front''' defined as the leading edge of a cooler and drier mass of air. The air with greater density wedges under the less dense warmer air, lifting it, which can cause the formation of a narrow line of [[showers]] and [[thunderstorms]] when enough [[moisture]] is present. This upward motion causes lowered [[pressure]] along the cold front. On [[weather map]]s, the surface position of the cold front is marked with the symbol of a blue line of triangles/spikes (pips) pointing in the direction of travel. A cold front's location is at the leading edge of the [[temperature]] drop off, which in an [[isotherm]] analysis would show up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface [[trough]]. Cold fronts can move up to twice as fast and produce sharper changes in weather than [[warm front]]s. Since cold air is denser than warm air it rapidly replaces the warm air preceding the boundary. Cold fronts are usually associated with an area of low pressure, and sometimes, a warm front.
==Precipitation==
[[Image:Example of a cold front.svg|thumb|Illustration of a cold front]]
A cold front commonly brings a narrow band of [[Precipitation (meteorology)|precipitation]] that follows along the leading edge of the cold front. These bands of precipitation are often very strong in nature, and especially in the [[Spring (season)|Spring]] and [[Summer]] months, can bring severe thunderstorms and/or [[tornadoes]]. In the spring, these cold fronts can be very strong, and can bring strong winds when the [[pressure gradient]] is tighter than normal. In the [[summer]], cold fronts can cause severe thunderstorms and [[hailstorms]], but in the [[winter]], cold fronts sometimes come through an area with little or no precipitation, and with little or no effect on temperature. In the [[autumn]] months, cold fronts rarely bring severe thunderstorms, but are known for bringing heavy, and widespread rainstorms. These rainstorms sometimes bring [[flooding]], and can move very slowly because cold fronts are more prone to slow movement in the fall. In the [[winter]], cold fronts can bring severe cold spells, and heavy snowstorms. The cold fronts in the late fall become more [[polar]] in nature, and tend to bring very cold weather, and temperature drops by up to 30°F.
==Temperature changes==
Cold fronts are the leading edge of a frigid air mass, hence the name 'cold front'. They can bring several [[cold]] spells in the [[fall]] ([[autumn]]) and [[winter]]. Very often, cold fronts are associated with deadly cold weather. Sometimes, though, cold fronts have no significant effect on the weather. When cold fronts come through, there is usually a quick, yet strong gust of wind, that shows that the cold front is passing. The effects from a cold front can last only a few hours to several weeks, depending on when the next weather front comes through.
==Association with warm fronts==
[[Image:Occluded_cyclone.svg|thumb|right|[[Occluded front|Occluded cyclone]] example. The triple point is the intersection of the cold, warm, and occluded fronts.]]
Cold fronts are very often associated with a [[warm front]], squall line, or other weather front. Very commonly, cold fronts have an adjacent warm front that is ahead of the cold front. This forms an area where warm air is occurring and interacting with the cold front. In this area known as a ''warm sector''. In the warm sector, very often severe thunderstorms, [[tornadoes]], and hailstorms occur, because of the sharp difference between the warm air that is associated with the warm front, and the cold air that is associated with the cold front.
==How cold fronts form==
Cold fronts form when a cooler air mass moves into an area of warmer air. The warmer air interacts with the cooler air mass along the boundary, and usually produces precipitation.
==See also==
*[[Weather front]]
==References==
* [http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/af/frnts/cfrnt/def.rxml Cold Front: transition zone from warm air to cold air]
==External links==
*[http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/af/frnts/cfrnt/def.rxml Cold Front]
*[http://serc.carleton.edu/NAGTWorkshops/visualization/collections/weather_fronts.html Weather Fronts]
*[http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/af/frnts/home.rxml Fronts: the boundaries between air masses]
[[Category:Weather fronts]]
[[cs:Studená fronta]]
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[[pl:Front chłodny]]
[[pt:Frente fria]]
[[ru:Холодный фронт]]
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