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 weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front. The air masses separated by a front usually differ in temperature and humidity. Cold fronts may feature narrow bands of thunderstorms and severe weather, and may on occasion be preceded by squall lines or dry lines. Warm fronts are usually preceded by stratiform precipitation and fog. The weather usually clears quickly after a front's passage. Some fronts produce no precipitation and little cloudiness, although there is invariably a wind shift.

Cold fronts and occluded fronts generally move from west to east, while warm fronts move poleward. Because of the greater density of air in their wake, cold fronts and cold occlusions move faster than warm fronts and warm occlusions. Mountains and warm bodies of water can slow the movement of fronts. When a front becomes stationary, and the density contrast across the frontal boundary vanishes, the front can degenerate into a line which separates regions of differing wind velocity, known as a shearline. This is most common over the open ocean.

Different air masses which affect North America, as well as other continents, tend to be separated by frontal boundaries. In this illustration, the Arctic front separates Arctic from Polar air masses, while the Polar front separates Polar air from warm air masses.

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

... that Eric Berger wrote about weather for the Houston Chronicle even before he became a certified meteorologist?
... 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 Japanese actor Kouhei Higuchi prepared for his role on the television drama adaptation of My Personal Weatherman by learning from a weather forecaster?
... that weather whiplash is the phenomenon of rapid swings between extremes of weather conditions?
... that the weather forecast for HD 189733 b is "Westerly winds at 2000 m/s, with molten glass showers"?
... that in the 1980s, "Sherman Bonner, The Human Thermometer" presented the weather on an Arkansas TV station?

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A cumulonimbus cloud near Swifts Creek, Victoria, Australia. Cumulonimbus are so named because they combine the characteristics of cumulus clouds (puffy in nature) and nimbus clouds (causing precipitation). They are typically around 30,000-50,000 ft (10,000-15,000 m) in height, and commonly produce precipitation and lightning. Cumulonimbus clouds occasionally become severe thunderstorms, and, if rotation is present in the atmosphere, can become supercells, producing high winds, heavy rain, hail, and rarely tornadoes. Fortunately, this only happens in a small fraction of cases; most cumulonimbus produce innocuous showers or thundershowers.

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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?

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Recent and ongoing weather

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This week in weather history...

June 1: Start of the Central Pacific and Atlantic hurricane seasons

1988: Tropical Depression One brought over 40 inches (100 cm) of rain to parts of Cuba, killing 37 people due to flooding.

June 2

1990: Thirty-seven tornadoes struck the US state of Indiana, the most ever recorded in that state in a single day.

June 3

2010: Cyclone Phet made landfall near Al Ashkharah, Oman, causing major flooding in the desert nation.

June 4

1958: A tornado outbreak killed 28 people in Wisconsin, including 21 deaths from a single F5 tornado.

June 5

1972: The United Nations Conference on the Human Environment began in Stockholm, Sweden.

June 6

1973: Hurricane Ava became the earliest Category 5 hurricane on record in the Pacific Ocean.

June 7

1997: Cyclone Keli formed in the South Pacific Ocean, the first tropical cyclone ever recorded in the month of June in that region.

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Wladimir Petrovich Köppen (/ˈkɜːpən/ KUR-pən; German: [ˈkœpn̩]; Russian: Влади́мир Петро́вич Кёппен, romanized: Vladímir Petróvich Kyoppen, IPA: [vlɐˈdʲimʲɪr pʲɪˈtrovʲɪtɕ ˈkʲɵp(ː)ʲɪn]; 25 September 1846 – 22 June 1940) was a Russian–German geographer, meteorologist, climatologist and botanist. 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 made significant contributions to several branches of science, and coined the name aerology for the science of measuring the upper air/atmosphere. (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!