Portal:Weather

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Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. 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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A tornado is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The most intense of all atmospheric phenomena, tornadoes come in many shapes and sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris and dust. Most tornadoes have wind speeds between 40 mph (64 km/h) and 110 mph (177 km/h), are approximately 250 feet (75 m) across, and travel a few miles (several kilometers) before dissipating. The most extreme can attain wind speeds of more than 300 mph (480 km/h), stretch more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 km).

Various types of tornadoes include the landspout, multiple-vortex tornado, and waterspout. Waterspouts have similar characteristics to tornadoes, characterized by a spiraling funnel-shaped wind current that form over bodies of water, connecting to large cumulus and thunderstorm clouds. These spiraling columns of air frequently develop in tropical areas close to the equator, and are less common at high latitudes. Other tornado-like phenomena which exist in nature include the gustnado, dust devil, fire whirls, and steam devil.

Tornadoes have been observed on every continent except Antarctica. The vast majority of tornadoes in the world occur in the Tornado Alley region of the United States, although they frequently occur in a large portion in North America. They also occasionally occur in south-central and eastern Asia, the Philippines, east-central South America, Southern Africa, northwestern and southeast Europe, western and southeastern Australia, and New Zealand. Tornadoes can be detected before or as they occur through the use of pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes, as well as by the efforts of storm spotters.

There are several different scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused, and has been replaced in some countries by the updated Enhanced Fujita scale. An F0 or EF0 tornado, the weakest category, damages trees but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and assign a rating.

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Did you know (auto-generated) - show different entries

... that in the 1980s, "Sherman Bonner, The Human Thermometer" presented the weather on an Arkansas TV station?
... that the weather forecast for HD 189733 b is "Westerly winds at 2000 m/s, with molten glass showers"?
... that an attempted British-Norwegian attack on the German battleship Tirpitz was abandoned after two Chariot manned torpedoes were lost due to bad weather?
... that after Irish post office clerk Maureen Flavin Sweeney reported worsening weather conditions, Dwight D. Eisenhower agreed to postpone D-Day by 24 hours?
... that weather whiplash is the phenomenon of rapid swings between extremes of weather conditions?
... that extreme event attribution estimates how much climate change causes weather events, such as the 2021 Western North America heat wave?

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An atmospheric gravity wave manifests itself as altocumulus undulatus clouds in an arid environment, in the Tadrart Acacus region of southeast Algeria.

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...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?

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Recent and ongoing weather

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This week in weather history...

April 16

1998: A deadly tornado outbreak struck Tennessee and Kentucky, including a rare F5 tornado that killed 3 people, and another tornado that struck downtown Nashville, Tennessee, killing one person.

April 17

1970: A multi-day tornado outbreak began in the southern High Plains of the United States, including 3 F4 tornadoes in the Texas Panhandle that killed 6 people.

April 18

2014: An avalanche killed 16 Sherpa guides working on Mount Everest.

April 19

2008: Typhoon Neoguri made landfall in Guangdong province of southern China, the earliest tropical cyclone to strike the nation in recorded history.

April 20

2012: Bhoja Air Flight 213 crashed while attempting to land in a thunderstorm, killing all 127 people aboard.

April 21

1965: A devastating tornado outbreak killed 58 people near Chicago.

April 22: Earth Day

1992: A subtropical cyclone, the first ever recorded in the Atlantic Ocean in the month of April, reached peak intensity far south of Bermuda.

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Vilhelm Friman Koren Bjerknes ForMemRS (/ˈbjɜːrknɪs/ BYURK-niss, Norwegian: [ˈbjæ̂rkneːs]; 14 March 1862 – 9 April 1951) was a Norwegian physicist and meteorologist who did much to found the modern practice of weather forecasting. He formulated the primitive equations that are still in use in numerical weather prediction and climate modeling, and he developed the so-called Bergen School of Meteorology, which was successful in advancing weather prediction and meteorology in the early 20th century. (Full article...)

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WikiProjects

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!