Portal:Weather

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The Weather Portal

Weather is an all-encompassing term used to describe all of the many and varied phenomena that occur in the atmosphere of a planet at a given time. The term usually refers to the activity of these phenomena over short periods of hours or days, as opposed to the term climate, which refers to the average atmospheric conditions over longer periods of time. When used without qualification, "weather" is understood to be the weather of Earth.

Weather most often results from temperature differences from one place to another, caused by the Sun heating areas near the equator more than the poles, or by different areas of the Earth absorbing varying amounts of heat, due to differences in albedo, moisture, and cloud cover. Surface temperature differences in turn cause pressure differences. A hot surface heats the air above it and the air expands, lowering the air pressure. The resulting pressure gradient accelerates the air from high to low pressure, creating wind, and Earth's rotation causes curvature of the flow via the Coriolis effect. These simple systems can interact, producing more complex systems, and thus other weather phenomena.

The strong temperature contrast between polar and tropical air gives rise to the jet stream. Most weather phenomena in the mid-latitudes are caused by instabilities of the jet stream flow (see baroclinity) or by weather fronts. Weather systems in the tropics are caused by different processes, such as monsoons or organized thunderstorm systems.

Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. In June the Northern Hemisphere is tilted towards the sun, while in December it is tilted away, causing yearly changes in the weather known as seasons. In the mid-latitudes, winter weather often includes snow and sleet, while in both the mid-latitudes and most of the tropics, tropical cyclones form in the summer and autumn. Almost all weather phenomena can occur year-round on different parts of the planet, including snow, rain, lightning, and, more rarely, hail and tornadoes.

Related portals: Earth sciences (Atmosphere  · Atmospheric Sciences)  · Tropical cyclones Featured article  · Disasters  · Water

Selected picture

DustStormInSpearmanTexas19350414.jpg

This dust storm occurred around Spearman, Texas on April 14, 1935. This was in the heart of the Dust Bowl, a period of severe dust storms and drought, which contributed to the Great Depression in the United States.

Recently selected pictures: Cordell, Oklahoma tornado, Mammatus clouds, Von Kármán vortex street, More...

Selected article

Satellite image of Hurricane Floyd over The Bahamas

Hurricane Floyd was the sixth named storm, fourth hurricane, and third major hurricane in the 1999 Atlantic hurricane season. Floyd triggered the third largest evacuation in US history (behind Hurricane Gustav and Hurricane Rita, respectively) when 2.6 million coastal residents of five states including Florida were ordered from their homes as Hurricane Floyd approached. The Cape Verde-type hurricane formed off the coast of Africa and lasted from September 7 to September 19, peaking in strength as a very strong Category 4 hurricane—just short of the highest possible rating—on the Saffir-Simpson Hurricane Scale. It was among the largest Atlantic hurricanes of its strength ever recorded.

Floyd struck The Bahamas at peak strength, causing heavy damage. It then paralleled the East Coast of the United States, causing massive evacuations and costly preparations. The storm weakened significantly, however, before making landfall in North Carolina as a Category 2 hurricane, and caused further damage as it traveled up the Mid-Atlantic region and into New England.

The hurricane produced torrential rainfall in eastern North Carolina, adding more rain to an area hit by Hurricane Dennis just weeks earlier. The rains caused widespread flooding over a period of several weeks; nearly every river basin in the eastern part of the state exceeded 500-year flood levels. In total, Floyd was responsible for 57 fatalities and $4.5 billion ($6.0 billion in 2008 U.S. dollars) in damage, mostly in North Carolina.

Recently selected articles: Hurricane Dean, Weather forecasting, Climate of India, More...

Did you know...

...that Hurricane Debbie is the only known tropical cyclone ever to strike Ireland?

...that the Tempest Prognosticator, one of the earliest attempts at a weather prediction device, employed live leeches in its operation?

...that eyewall replacement cycles are among the biggest challenges in forecasting tropical cyclone intensity?

...that the Braer Storm of January 1993 is the strongest extratropical cyclone ever recorded in the north Atlantic Ocean?

...that in medieval lore, Tempestarii are magicians with the power to control the weather?

...that the omega equation is essential to numerical weather prediction?

Recent and ongoing weather

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This week in weather history...

January 25

1990: A European windstorm known as the Burns' Day storm killed almost 100 people, mainly in the United Kingdom.

2008: The first in a series of winter storms impacted China, beginning what would be China's most severe winter in half a century.

January 26

1978: The Great Blizzard of 1978 struck the Great Lakes and Ohio Valley with several feet of snow and winds gusting to 100 mph. Seventy people died in the storm.

January 27

1982: The World Airways Flight 30 skidded off an icy runway at Boston Logan International Airport, killing 2 people.

2008: Cyclone Gene made landfall on Fiji, killing 8 people.

January 28

1922: The Knickerbocker Storm, one of the worst blizzards ever to strike Washington, D.C., collapsed the roof of the Knickerbocker Theater, killing 98 people.

1977: A severe blizzard which would last five days hit western New York.

2004: Cyclone Elita made its first of three landfalls on Madagascar.

January 29

1992: Tropical Storm Ekeka reached hurricane strength, the earliest and southernmost hurricane ever to form in the eastern Pacific Ocean.

January 30

1930: The first radiosonde was launched in Pavlovsk, USSR by Pavel Molchanov, sending weather data from high in the atmosphere to the Leningrad Weather Bureau and Moscow Central Forecast Institute.

2009: A severe heat wave reached its peak in southeastern Australia, with nearly half of Tasmania recording all-time record temperatures as high as 42 °C (108 °F).

January 31

1966: Oswego, New York received 50 inches (127 cm) of snow, which was the last of five consecutive days of heavy snow.

Selected biography

Clement Lindley Wragge (September 19, 1852 – December 10, 1922) was a meteorologist born in Stourbridge, Worcestershire, England. After training in law, Wragge became renowned in the field of meteorology, winning the Scottish Meteorological Society's Gold Medal. He set up an extensive network of weather stations around Australia, and was the first to give human names to cyclones. He traveled widely, and in his later years was a reliable authority on Australia, India and the Pacific Islands.


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Categories

Weather: Meteorology | Atmosphere | Basic meteorological concepts and phenomena | Climate | Clouds | Cyclones | Floods | Precipitation| Seasons | Severe weather and convection | Snow | Storms | Tornadoes | Tropical cyclones | Weather events | Weather lore | Weather hazards | Weather modification | Weather prediction | Weather warnings and advisories| Winds

Wikiprojects

WikiProject Meteorology is a collaborative effort by dozens of Wikipedians to improve the quality of meteorology- and weather-related articles. If you would like to help, visit the project talk page, and see what needs doing.

WikiProject Severe weather is a similar project specific to articles about severe weather. Their talk page is located here.

WikiProject Tropical cyclones is a daughter project of WikiProject meteorology. The dozens of semi-active members and several full-time members focus on improving Wikipdia's coverage of tropical cyclones.

WikiProject Non-tropical storms is a collaborative project to improve articles related to winter storms, wind storms, and extratropical weather.

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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