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Weather is the state of the Earth's atmosphere at a specific place and time, typically described in terms of temperature, humidity, cloud cover, and stability. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature, precipitation, and other atmospheric conditions, whereas climate 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 by air pressure, temperature, and moisture differences between one place and another. These differences can occur due to the Sun's angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations: the Hadley cell, the Ferrel cell, the polar cell, and the jet stream. Weather systems in the middle latitudes, such as extratropical cyclones, are caused by instabilities of the jet streamflow. Because Earth's axis is tilted relative to its orbital plane (called the ecliptic), sunlight is incident at different 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's orbit can affect the amount and distribution of solar energy received by Earth, thus influencing long-term climate and global climate 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 the atmosphere for a future time and a given location. Earth's weather system is a chaotic 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 to control the weather have occurred throughout history, and there is evidence that human 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 the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years. However, the weather is not limited to planetary bodies. A star'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 the Sun is known as the solar wind. (Full article...)
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Tropical Storm Allison was a tropical storm that devastated southeast Texas in June of the 2001 Atlantic hurricane season. The first storm of the season, Allison lasted unusually long for a June storm, remaining tropical or subtropical for 15 days. The storm developed from a tropical wave in the northern Gulf of Mexico on June 4, 2001, and struck the upper Texas coast shortly thereafter. It drifted northward through the state, turned back to the south, and re-entered the Gulf of Mexico. The storm continued to the east-northeast, made landfall on Louisiana, then moved across the southeast United States and Mid-Atlantic. Allison was the first storm since Tropical Storm Frances in 1998 to strike the northern Texas coastline.
The storm dropped heavy rainfall along its path, peaking at over 40 inches (1,000 mm) in Texas. The worst flooding occurred in Houston, where most of Allison's damage occurred: 30,000 became homeless after the storm flooded over 70,000 houses and destroyed 2,744 homes. Downtown Houston was inundated with flooding, causing severe damage to hospitals and businesses. Twenty-three people died in Texas. Throughout its entire path, Allison caused $5.5 billion ($6.7 billion 2008 USD) in damage and 41 deaths. Aside from Texas, the places worst hit were Louisiana and southeastern Pennsylvania.
Following the storm, President George W. Bush designated 75 counties along Allison's path as disaster areas (the first time he had to do so), which enabled the citizens affected to apply for aid. Allison is the only tropical storm to have its name retired without ever having reached hurricane strength.
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Did you know (auto-generated) -
- ... that state representative Karl Bohnak, referring to his former profession, said that the Upper Peninsula of Michigan was one of the most challenging places in the U.S. to forecast the weather?
- ... that Richard Davis made the earliest known continuous land-based weather recordings in New Zealand?
- ... that Come In was recorded on a hands-free microphone attached to a pair of headphones?
- ... that Japanese actor Kouhei Higuchi prepared for his role on the television drama adaptation of My Personal Weatherman by learning from a weather forecaster?
- ... that environment minister Peng Chi-ming drafted Taiwan's first weather insurance policy?
- ... that MyRadar uses a custom satellite constellation to help forecast the weather?
Selected image
This tornado struck the town of Elie, Manitoba on June 22, 2007. It was the first tornado outside the United States to be rated F5 on the Fujita scale, the most severe level of tornado damage.
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More did you know...
...that the Flying river is the name given to the transport of water vapor from the Amazon rainforest to southern Brazil?
...that hurricane shutters are required for all homes in Florida unless impact-resistant glass is used?
...that the Joint Institute for Marine and Atmospheric Research is a combined weather and ocean research institute with the cooperation of the Office of Oceanic and Atmospheric Research and the University of Hawaiʻi?
...that the SS Central America was sunk by a hurricane while carrying more than 30,000 pounds (13,600 kg) of gold, contributing to the Panic of 1857?
...that a hurricane force wind warning is issued by the United States National Weather Service for storms that are not tropical cyclones but are expected to produce hurricane-force winds (65 knots (75 mph; 120 km/h) or higher)?
...that the Automated Tropical Cyclone Forecasting System is a software package for tropical cyclone forecasting developed in 1988 that is still used today by meteorologists in various branches of the US Government?
Recent and ongoing weather
This week in weather history...
October 23
1091: The London tornado of 1091, the earliest and possibly strongest know tornado in the history of the British Isles, hit downtown London, killing two people.
October 24
1988: The passenger ferry MV Doña Marilyn sank while sailing from Manila to Tacloban, Philippines during Typhoon Ruby, killing at least 77 passengers, though there were reports of almost 400 killed. The storm also killed more than 200 people elsewhere in the Philippines.
October 25
1992: Tropical Storm Zeke, the record-breaking 24th named storm of the 1992 Pacific hurricane season, formed over the open ocean south of Baja California.
October 26
1996: An unusual autumn tornado outbreak struck the northern Great Plains, including 14 in Minnesota, which was more than had ever struck the state for the entire month of October.
October 27
1959: An unnamed hurricane, the deadliest and one of the strongest ever to make landfall in the northeastern Pacific Ocean, struck Mexico near Manzanillo, Colima, killing around 1800 people.
October 28
1996: The extratropical remnants of Hurricane Lili struck Great Britain, causing ₤150 million in damage and killing two people.
October 29
1867: The San Narciso hurricane struck the Dutch West Indies (present-day Virgin Islands) and Puerto Rico, killing at least 811 people.
Selected biography
Sakuhei Fujiwhara (藤原 咲平, Fujiwara Sakuhei; October 29, 1884 – September 22, 1950) was a Japanese meteorologist who became the namesake for the Fujiwhara effect. Novelist Jirō Nitta is his nephew and mathematician Masahiko Fujiwara is his grandnephew. (Full article...)
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- Featured Article Review: 2005 Atlantic hurricane season (Discussion)
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The scope of WikiProject 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 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 Wikipedia's coverage of tropical 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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