The weather portal

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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The Ice Storm of 1998 (also known as Ice Storm '98) was a massive ice storm that struck areas of Eastern Ontario, southern Québec, and Nova Scotia in Canada, and bordering areas from Northern New York to Northern Maine in the United States. From January 4-10, 1998, up to 5 inches (120 mm) of ice accumulated on surfaces in these areas due to an unusually long period of freezing rain. The tremendous weight of ice accretion caused massive damage to trees and electrical infrastructure all over the area, leading to widespread power outages. Millions were left without power for periods varying from days to weeks, leading to more than 30 fatalities, a shut down of activities in large cities like Montreal and Ottawa, and an unprecedented reconstruction of the power grid. More than $5 million in damages were attributed to this storm.

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Virga is precipitation which evaporates before reaching the ground, forming a translucent, wispy cloud. It can be seen descending from the dark foreground clouds over the London skyline in this May, 2007 photograph.

Recently selected pictures: Hurricane Isabel satellite, Hurricane Katrina Eye, Lightning strike near Swifts Creek, Victoria, Australia, 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...

July 13

2010: Typhoon Conson struck the northern Philippines, killing more than 100 people.

July 14

1977: The first of the Himawari series of weather satellites, operated by the Japan Meteorological Agency, was launched from Cape Canaveral Air Force Station.

July 15

2001: The South African Weather Service was formed.

July 16

1904: A destructive tornado struck Chappaqua, New York, killing two people.

July 17

2013: Tropical Storm Cimaron formed near Calayan, Cagayan, Philippines. A lightning strike from the storm in Ilocos Sur killed two people.

July 18

1996: An F5 tornado struck the village of Oakfield, Wisconsin.

July 19

1983: A derecho, which moved along a path parallel to Interstate 94 from Minnesota to Illinois, knocked out power to 250,000 people and injured at least 34.

Selected biography

Robert FitzRoy

Vice-Admiral Robert FitzRoy FRS (5 July 1805 – 30 April 1865) was an English officer of the Royal Navy and a scientist. He achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, FitzRoy's second expedition to Tierra del Fuego and the Southern Cone.

FitzRoy was a pioneering meteorologist who made accurate daily weather predictions, which he called by a new name of his own invention: "forecasts". In 1854 he established what would later be called the Met Office, and created systems to get weather information to sailors and fishermen for their safety. He was an able surveyor and hydrographer. As Governor of New Zealand, serving from 1843 to 1845, he tried to protect the Māori from illegal land sales claimed by British settlers. (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!

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