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.
Hurricane Vince was an unusual hurricane which developed in the northeastern Atlantic basin. Forming in October during the 2005 Atlantic hurricane season, the waters over which it developed were considered too cold for tropical development. Vince was the 20th named tropical cyclone and 12th hurricane of the extremely active season. Vince developed from a non-tropical system on October 8, becoming a subtropical storm southeast of the Azores. The National Hurricane Center (NHC) did not officially name the storm until the next day, shortly before Vince became a hurricane. The storm weakened at sea and, on October 11, made landfall on the Iberian Peninsula as a tropical depression. Vince was the first tropical system to do so since the 1842 Spain hurricane. It dissipated over Spain, bringing much needed rain to the region, and its remnants passed into the Mediterranean Sea...
...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
1999: Hurricane Lenny made landfall on Saint Croix. It was an unusual storm in many ways, striking the island as the strongest Atlantic hurricane on record for the month of November, while moving in an unprecedented west-to-east direction through the Caribbean Sea.
John Park Finley (April 11, 1854 – November 24, 1943) was an American meteorologist and Army Signal Service officer who was the first person to study tornadoes intensively. He wrote the first known scientific book on the subject of tornadoes, as well as many other manuals and booklets. He was responsible for the first national network for reporting tornado touchdowns and outbreaks, and kept an archive of tornado reports from across the United States. He also collected vast climatological data, set up a nationwide weather observer network, started one of the first private weather enterprises, and opened an early aviation weather school.
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