Portal:Weather
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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 · Atmospheric Sciences) · Tropical cyclones 
· Disasters · Water
Virga is precipitation which evaporates before reaching the ground, forming a translucent, wispy cloud. It can be seen decending from the dark foreground clouds over the London skyline in this May, 2007 photograph.
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Wladimir Köppen (September 25, 1846 — June 22, 1940) was a Russian born geographer, meteorologist, climatologist and botanist of German descent. After studies in St. Petersburg, he spent the bulk of his life and professional career in Germany and Austria. His most notable contribution to science was the development of the Köppen climate classification system, which, with some modifications, is still commonly used. Köppen was one of the last scholars with a broad enough background and intellectual ability to make significant contributions to several branches of science.
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- Wikinews weather portal
- October 8: Passenger plane crashes in Nepal killing 18
- October 4: Hurricanes may be associated with sunspots
- September 21: Fresh floods in India claims sixteen lives
- September 9: 50,000 people refuse evacuation after flooding in India caused by river changing course
- September 8: Hurricane Ike makes landfall on Cuba
- Winter storms of 2008–09
- 2008-09 South-West Indian Ocean cyclone season
- 2008 Pacific typhoon season
- Tornadoes of 2008
October 10
1780: The Great Hurricane of 1780, the deadliest tropical cyclone ever in the Atlantic Ocean, began its trek through the Carribean Sea, which eventually led to the deaths of 27,500 people.
October 11
1846: The Great Havana Hurricane of 1846 killed 163 people in Cuba.
October 12
1634: The Burchardi flood struck the north coast of Germany and Denmark, killing thousands.
1962: The Columbus Day Storm brought damaging winds of more than 100 mph (160 km/h) to a large area of the Pacific Northwest.
1979: The record lowest surface air pressure outside of a tornado, 870 mbar, was measured in the eye of Typhoon Tip.
October 13
2006: Lake Storm "Aphid" dumped two feet of incredibly heavy snow on Buffalo, New York, destroying 90% of the city's trees and resulting in 13 deaths.
October 15
1987: The Great Storm of 1987 hit France and England.
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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
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.
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