Weather is an all-encompassing term used to describe all of the many and varied phenomena that occur in the atmosphere of a planet at a given time. The term usually refers to the activity of these phenomena over short periods of hours or days, as opposed to the term climate, which refers to the average atmospheric conditions over longer periods of time. When used without qualification, "weather" is understood to be the weather of Earth.
Weather most often results from temperature differences from one place to another, caused by the Sun heating areas near the equator more than the poles, or by different areas of the Earth absorbing varying amounts of heat, due to differences in albedo, moisture, and cloud cover. Surface temperature differences in turn cause pressure differences. A hot surface heats the air above it and the air expands, lowering the air pressure. The resulting pressure gradient accelerates the air from high to low pressure, creating wind, and Earth's rotation causes curvature of the flow via the Coriolis effect. These simple systems can interact, producing more complex systems, and thus other weather phenomena.
The strong temperature contrast between polar and tropical air gives rise to the jet stream. Most weather phenomena in the mid-latitudes are caused by instabilities of the jet stream flow (see baroclinity) or by weather fronts. Weather systems in the tropics are caused by different processes, such as monsoons or organized thunderstorm systems.
Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. In June the Northern Hemisphere is tilted towards the sun, while in December it is tilted away, causing yearly changes in the weather known as seasons. In the mid-latitudes, winter weather often includes snow and sleet, while in both the mid-latitudes and most of the tropics, tropical cyclones form in the summer and autumn. Almost all weather phenomena can occur year-round on different parts of the planet, including snow, rain, lightning, and, more rarely, hail and tornadoes.
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.
...that the Tempest Prognosticator, one of the earliest attempts at a weather prediction device, employed live leeches in its operation?
...that in medieval lore, Tempestarii are magicians with the power to control the weather?
- Wikinews weather portal
- May 4: Six dead following flash flooding in Palestine, Texas
- May 2: 60 people still missing after Kenyan house collapse
- December 2: Investigators blame pilot error for AirAsia crash into Java Sea
- October 19: Typhoon Koppu makes landfall in the Philippines, displacing at least 16,000
- September 11: Typhoon Etau causes more leakage at Fukushima
- 2018 Atlantic hurricane season
- 2018 Pacific typhoon season
- Tornadoes of 2018
1997: Hurricane Danny formed as Tropical Depression Four, eventually dropping 36.71 inches (932 mm) of rain on Dauphin Island, Alabama. This was the most rain ever recorded from a tropical cyclone in the state.
Dr. Robert Homer Simpson (born November 19, 1912) is an American meteorologist and hurricane specialist. He was the first director of the National Hurricane Research Project (1955-1959), and a former director (1967-1974) of the National Hurricane Center. He is also the co-developer of the Saffir-Simpson Hurricane Scale, used for measuring tropical cyclone intensity in the Western Hemisphere.
- Tropical Storm Debby (2006)
- 1991 Pacific hurricane season
- Tropical Storm Laura (2008)
- Tropical cyclone observation
Template:/box-header Weather: Meteorology | Atmosphere | Basic meteorological concepts and phenomena | Climate | Clouds | Cyclones | Floods | Precipitation| Seasons | Severe weather and convection | Snow | Storms | Tornadoes | Tropical cyclones | Weather events | Weather lore | Weather hazards | Weather modification | Weather prediction | Weather warnings and advisories| Winds Template:/box-footer
Template:/box-header 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 Tropical cyclones is a daughter project of WikiProject meteorology. The dozens of semi-active members and several full-time members focus on improving Wikipdia's coverage of tropical cyclones.
WikiProject Non-tropical storms is a collaborative project to improve articles related to winter storms, wind storms, and extratropical weather.
Here are some tasks you can do: