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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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Satellite image of the storm
Satellite image of the storm

The Christmas 1994 nor'easter was an intense cyclone along the East Coast of the United States and Atlantic Canada. It developed from an area of low pressure in the southeast Gulf of Mexico near the Florida Keys, and moved across the state of Florida. As it entered the warm waters of the Gulf Stream in the Atlantic Ocean, it began to rapidly intensify, exhibiting traits of a tropical system, including the formation of an eye. It attained a pressure of 970 millibars on December 23 and 24, and after moving northward, it came ashore near New York City on Christmas Eve. Due to the uncertain nature of the storm, the National Hurricane Center (NHC) did not classify it as a tropical cyclone.

Heavy rain from the developing storm contributed to significant flooding in South Carolina. Much of the rest of the East Coast was affected by high winds, coastal flooding, and beach erosion. New York State and New England bore the brunt of the storm; damage was extensive on Long Island, and in Connecticut, 130,000 households lost electric power during the storm. Widespread damage and power outages also occurred throughout Rhode Island and Massachusetts, where the storm generated 30-foot (9.1 m) waves along the coast. Due to the warm weather pattern that contributed to the storm's development, precipitation was limited to rain. Two people were killed, and damage amounted to at least $21 million dollars.

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An animation of changing snow cover across the Earth over the period of a year. Snow cover is much more abundant in the Northern Hemisphere, which is not surprising considering that the large majority of land in the colder latitudes is in the Northern Hemisphere. Antarctica is perennially covered by snow or ice cap, except for a few places in the Antarctic Peninsula and the McMurdo Dry Valleys.

Recently selected pictures: Snow flakes, Sun dogs, Pyrocumulus clouds, More...

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...

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.

June 8

1953: On the second day of a deadly three-day tornado outbreak, an F5 tornado killed 116 people in Flint, Michigan.

June 9

1972: Intense rainfall led to the failure of Canyon Lake Dam along Rapid Creek near Rapid City, South Dakota. The resulting flooding killed 238 people and caused over $160 million in damage.

June 10

1682: The first known tornado in the history of Connecticut caused severe tree damage in the southwestern part of the state.

Selected biography

Picture of Ted Fujita

Tetsuya Theodore Fujita (/fˈtɑː/; FOO-jee-tah) (藤田 哲也, Fujita Tetsuya, October 23, 1920 – November 19, 1998) was a Japanese-American meteorologist whose research primarily focused on severe weather. His research at the University of Chicago on severe thunderstorms, tornadoes, hurricanes, and typhoons revolutionized the knowledge of each. Although he is best known for creating the Fujita scale of tornado intensity and damage, he also discovered downbursts and microbursts and was an instrumental figure in advancing modern understanding of many severe weather phenomena and how they affect people and communities, especially through his work exploring the relationship between wind speed and damage. (Full article...)

Previously selected biographies: Sakuhei Fujiwhara, Robert Simpson, More...

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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!

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