APOD and General Astronomy Discussion Forum
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Stephen Rasey wrote:That sounds like a "hurricane" to me. A polar cyclone, but a hurricane by another name.“The most powerful storm to affect the Bering Sea coast of Alaska in 37 years is pounding Alaska’s west coast and Eastern Siberia with hurricane-force winds, a destructive storm surge up to 7 feet high, waves up to 35 feet high, and blinding snow,” ...." central pressure of 945 mb." ... "6 foot storm surge in Nome Alaska." -- November 8-9, 2011.
Should storms like these be on the map?
http://en.wikipedia.org/wiki/Polar_cyclone wrote: <<A polar vortex (also known as Polar cyclones, polar vortices, Arctic cyclones, sub-polar cyclones, and the circumpolar whirl) is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer. They usually span 1,000–2,000 kilometers in which the air is circulating in a counter-clockwise fashion (in the northern hemisphere). The reason for the rotation is the same as any other cyclone, the Coriolis effect.
Other astronomical bodies are also known to have polar vortices, including Venus (double vortex - that is, two polar vortices at a pole ), Mars, Jupiter, Saturn and Saturn's moon Titan.>>
http://en.wikipedia.org/wiki/Tropical_cyclone wrote: <<A tropical cyclone is a storm system characterized by a low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. They usually span 300–700 kilometers. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic windstorms such as nor'easters, European windstorms, and polar lows. The characteristic that separates tropical cyclones from other cyclonic systems is that at any height in the atmosphere, the center of a tropical cyclone will be warmer than its surroundings; a phenomenon called "warm core" storm systems. A tropical cyclone's primary energy source is the release of the heat of condensation from water vapor condensing, with solar heating being the initial source for evaporation. Therefore, a tropical cyclone can be visualized as a giant vertical heat engine supported by mechanics driven by physical forces such as the rotation and gravity of the Earth. In another way, tropical cyclones could be viewed as a special type of mesoscale convective complex, which continues to develop over a vast source of relative warmth and moisture. While an initial warm core system, such as an organized thunderstorm complex, is necessary for the formation of a tropical cyclone, a large flux of energy is needed to lower atmospheric pressure more than a few millibars (0.10 inch of mercury). The inflow of warmth and moisture from the underlying ocean surface is critical for tropical cyclone strengthening. A significant amount of the inflow in the cyclone is in the lowest 1 kilometre of the atmosphere.>>
Polar cyclone is synonymous with polar vortex, not to be confused with a polar low.Stephen Rasey wrote:Polar Vortex and Polar Cyclones are different things.
A polar vortex that you describe has it's eye on or near the pole.
A polar cyclone, or a polar low, such as the Nov. 2011 storm described in the Bering Sea is warm center convection cyclonic storm, albeit with a very cold upper atmosphere over a cool sea. It is a traveling low pressure storm system. http://nsidc.org/arcticmet/patterns/polar_low.html
Even though cyclone is a synonym for both hurricane and typhoon, but not for vortex. --thesaurus.com. Go figure.Polar lows have been referred to by many other terms, such as polar mesoscale vortex, Arctic hurricane, Arctic low, and cold air depression. Today the term is usually reserved for the more vigorous systems that have near-surface winds of at least 17 m/s.[30]-- Wikipedia-Polar Low
The subject is "water" NOT "evaporation" :Henk wrote:
I'm a bit surprised by the remark in the original text that 'evaporation of warm water gives hurricanes their energy'.
Evaporation costs energy, it's the condensation afterwards that can give off the energy again...
A combination of factors led to having little or no records pre-1950. The most obvious is the lack of satellite observation. Additionally, there has never been much shipping passed the Eastern South American coast during the southern summer. Even before the Panama Canal opened, most commercial shipping passed around Southern Africa or passed through in Spring and Fall. There also has been much less naval warfare in the region, so a lack of recorded observation.do_japan wrote:Why is there no record of Hurricanes/Typhoons in the southern hemisphere before 1950?
The eye of Typhoon VaMei remained in the Northern Hemisphere:Luiz wrote:
A portion of Typhoon Varnei http://en.wikipedia.org/wiki/Tropical_Storm_Vamei has indeed crossed equator.
Catarina is the only South Atlantic cyclone known to have reached hurricane strength.Luiz wrote:
There were another South Atlantic hurricane besides 2003 Catarina, check November 19th 1980 in the same region.
http://en.wikipedia.org/wiki/South_Atlantic_tropical_cyclone wrote:
<<South Atlantic tropical cyclones are unusual weather events that occur in the southern hemisphere. Strong wind shear (which disrupts cyclone formation) and a lack of weather disturbances favorable for tropical cyclone development make any hurricane-strength cyclones extremely rare. If a "hurricane season" were to be demarcated in the South Atlantic, it would most likely be the opposite of the North Atlantic season, from November to the end of April with mid-March being the peak when the oceans are warmest in the Southern Hemisphere. These tropical cyclones would be given identifiers starting with SL in the future.
According to a study published in 2008, there were 92 subtropical cyclones in the Southern Atlantic between 1957 and 2008.>>
