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Weather refers to the state of the Earth'satmosphere at a specific place and time, typically described in terms of temperature, humidity,cloud cover, andstability. OnEarth, most weather phenomena occur in the lowest layer of the planet'satmosphere, thetroposphere, just below thestratosphere. Weather refers to day-to-day temperature,precipitation, and other atmospheric conditions, whereasclimate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, "weather" is generally understood to mean the weather of Earth.
Weather is driven byair pressure,temperature, andmoisture differences between one place and another. These differences can occur due to theSun's angle at any particular spot, which varies withlatitude. The strong temperature contrast between polar and tropical air gives rise to the largest scaleatmospheric circulations: theHadley cell, theFerrel cell, thepolar cell, and thejet stream. Weather systems in themiddle latitudes, such asextratropical cyclones, are caused by instabilities of the jet streamflow. Because Earth'saxis is tilted relative to itsorbital plane (called theecliptic),sunlight is incident atdifferent angles at different times of the year. On Earth's surface, temperatures usually range ±40 °C (−40 °F to 104 °F) annually. Over thousands of years, changes in Earth'sorbit can affect the amount and distribution ofsolar energy received by Earth, thus influencing long-term climate and globalclimate change.
Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes, as most atmospheric heating is due to contact with the Earth's surface while radiative losses to space are mostly constant.Weather forecasting is the application of science and technology to predict the state of theatmosphere for a future time and a given location. Earth's weather system is achaotic system; as a result, small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts tocontrol the weather have occurred throughout history, and there is evidence thathuman activities such as agriculture and industry have modified weather patterns.
Studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in theSolar System, Jupiter'sGreat Red Spot, is ananticyclonic storm known to have existed for at least 300 years. However, the weather is not limited to planetary bodies. Astar's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from theSun is known as thesolar wind. (Full article...)
Ajet stream is a fast flowing, relatively narrowair current found at thetropopause, the transition between thetroposphere (where temperature decreases with height) and thestratosphere (where temperature increases with height). Jet streams are typically located at 10-15 kilometers above the surface of theEarth. They form near boundaries of adjacent air masses with significant differences intemperature, such as thepolar region and the warmer air to the south. The path of the jet typically has ameandering shape, and these meanders known asRossby waves. Rossby waves propagate westward with respect to the flow in which they are embedded, which translates to a slower eastward migration across the globe than smaller scaleshort wave troughs. The major jet streams are westerly winds (flowing west to east) in theNorthern Hemisphere.
During thesummer, low-level easterly jets can form in tropical regions. A southerly low level jet in theGreat Plains of North America helps fuel overnightthunderstorm activity, normally in the form ofmesoscale convective systems. A similar northerly low-level jet can form acrossAustralia, instigated by cut-off lows which develop across southwest portions of the country.
Meteorologists use the location of the jet stream as an aid inweather forecasting. The main commercial use of the jet stream is during airline travel, as flying long distances along the jet stream can cut hours off a long distance trip. One type ofclear-air turbulence is found in the jet stream's vicinity, which can be a hazard to aircraft. One future benefit of the jet stream could be to augment power generation within the next 10 to 20 years, if technological hurdles can be overcome.
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Anoctilucent cloud photographed fromSoomaa National Park,Estonia. Noctilucent clouds are the highest clouds that form on Earth, being found in themesosphere at altitudes of more than 70 kilometres (43 mi) above the ground. They are also among the rarest seen types of clouds: they are very dim (can only be seen after sunset illuminated by the sun below the horizon), and are typically only seen at latitudes between 50 and 70 degrees from the equator during the summertime.
...that theFlying river is the name given to the transport ofwater vapor from theAmazon rainforest to southernBrazil?
...thathurricane shutters are required for all homes inFlorida unless impact-resistant glass is used?
...that theJoint Institute for Marine and Atmospheric Research is a combined weather and ocean research institute with the cooperation of theOffice of Oceanic and Atmospheric Research and theUniversity of Hawaiʻi?
...that theSS Central America was sunk by ahurricane while carrying more than 30,000 pounds (13,600 kg) of gold, contributing to thePanic of 1857?
...that ahurricane force wind warning is issued by theUnited StatesNational Weather Service for storms that are nottropical cyclones but are expected to produce hurricane-force winds (65 knots (75 mph; 120 km/h) or higher)?
...that theAutomated Tropical Cyclone Forecasting System is a software package fortropical cycloneforecasting developed in 1988 that is still used today bymeteorologists in various branches of theUS Government?
1992:Cyclone Forrest, which had prompted unprecedented evacuations inBangladesh before veering eastward, made landfall in northwesternMyanmar causing relatively minor damage.
1970:Typhoon Patsy struck the coast ofVietnam, causing major damage and killing more than 200 people.
1984: An unusually strongearly-season Nor'easter reached its peak intensity off the coast ofFlorida.
1703: Anintense European windstorm began to affect southern England and theEnglish Channel. This storm or series of storms would last for more than a week, killing as many as 15,000 at sea.
2003:Typhoon Lupit passed close toUlithi,FSM, completely inundating theatoll.
2009:Typhoon Nida, one of the most powerful typhoons of the decade, reached peak intensity over the northwesternPacific Ocean, withmaximum sustained winds of 285 kilometres per hour (180 mph).
1997: TheTropical Rainfall Measuring Mission satellite was launched.
Tetsuya Theodore Fujita (/ˈfuːdʒiːtɑː/;FOO-jee-tah) (藤田 哲也,Fujita Tetsuya; October 23, 1920 – November 19, 1998) was a Japanese and Americanmeteorologist whose research primarily focused on severe weather. His research at theUniversity of Chicago on severe thunderstorms, tornadoes, hurricanes, and typhoons revolutionized the knowledge of each. Although he is best known for creating theFujita scale oftornado intensity and damage, he also discovereddownbursts andmicrobursts and was an instrumental figure in advancing modern understanding of many severe weather phenomena and how they affect people, airplanes, and communities, especially through his work exploring the relationship between wind speed and damage. (Full article...)
Previously selected biographies:Sakuhei Fujiwhara,Robert Simpson,More...
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The scope ofWikiProject Weather is to have a single location for all weather-related articles on Wikipedia.
WikiProject Meteorology is a collaborative effort by dozens of Wikipedians to improve the quality ofmeteorology- andweather-related articles. If you would like to help, visit theproject talk page, and see what needs doing.
WikiProject Severe weather is a similar project specific to articles aboutsevere weather. Their talk page is locatedhere.
WikiProject Tropical cyclones is a daughter project of WikiProject meteorology. The dozens of semi-active members and several full-time members focus on improving Wikipedia's coverage oftropical cyclones.
WikiProject Non-tropical storms is a collaborative project to improve articles related to winter storms, wind storms, and extratropical cyclones.
Wikipedia is a fully collaborative effort by volunteers. So if you see something you think you can improve,be bold and get to editing! We appreciate any help you can provide!
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