In meteorology, a cyclone is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above. Cyclones are characterized by inward-spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes, and dust devils lie within the smaller mesoscale.
A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning, heavy precipitation, heavy freezing rain, strong winds, wind transporting some substance through the atmosphere such as in a dust storm, among other forms of severe weather.
A nor'easter is a large-scale extratropical cyclone in the western North Atlantic Ocean. The name derives from the direction of the winds that blow from the northeast. Typically, such storms originate as a low-pressure area that forms within 100 miles (160 km) of the shore between North Carolina and Massachusetts. The precipitation pattern is similar to that of other extratropical storms, although nor'easters are usually accompanied by heavy rain or snow, and can cause severe coastal flooding, coastal erosion, hurricane-force winds, or blizzard conditions. They tend to develop most often and most powerfully between the months of November and March, because of the difference in temperature between the cold polar air mass coming down from central Canada and the warm ocean waters off the upper East Coast. The susceptible regions—the upper north Atlantic coast of the United States and the Atlantic Provinces of Canada—are generally impacted by nor'easters a few times each winter.
Project Stormfury was an attempt to weaken tropical cyclones by flying aircraft into them and seeding them with silver iodide. The project was run by the United States Government from 1962 to 1983. The hypothesis was that the silver iodide would cause supercooled water in the storm to freeze, disrupting the inner structure of the hurricane, and this led to seeding several Atlantic hurricanes. However, it was later shown that this hypothesis was incorrect. It was determined that most hurricanes do not contain enough supercooled water for cloud seeding to be effective. Additionally, researchers found that unseeded hurricanes often undergo the same structural changes that were expected from seeded hurricanes. This finding called Stormfury's successes into question, as the changes reported now had a natural explanation.
The 1993 Storm of the Century was a cyclonic storm that formed over the Gulf of Mexico on March 12, 1993. The cold weather, heavy snowfall, high winds and storm surges that the storm brought affected a very large area; at its height, it stretched from Canada to Honduras. The cyclone moved through the Gulf of Mexico and then through the eastern United States before moving on to eastern Canada. It eventually dissipated in the North Atlantic Ocean on March 15.
Hurricane Catarina, or Cyclone Catarina was an extraordinarily rare South Atlantic tropical cyclone, the only hurricane-strength storm on record in the South Atlantic Ocean. Catarina made landfall on Southern Brazil at peak intensity, with the equivalent of Category 2 hurricane-force sustained winds, on 28 March 2004.
The appearances of tropical cyclones in popular culture spans many genres of media and encompasses many different plot uses.
A Pacific hurricane is a tropical cyclone that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regions: the eastern, central, and western, while the southern Pacific is divided into 2 sections, the Australian region and the southern Pacific basin between 160°E and 120°W. Identical phenomena in the western north Pacific are called typhoons. This separation between the two basins has a practical convenience, however, as tropical cyclones rarely form in the central north Pacific due to high vertical wind shear, and few cross the dateline.
The 1991 Perfect Storm, also known as The No-Name Storm and the Halloween Gale/Storm, was a damaging and deadly nor'easter in October 1991. Initially an extratropical cyclone, the storm absorbed Hurricane Grace to its south and evolved into a small unnamed hurricane later in its life. Damage from the storm totaled over $200 million and thirteen people were killed in total, six of which were an outcome of the sinking of Andrea Gail, which inspired the book and later movie, The Perfect Storm. The nor'easter received the name, playing off the common expression, after a conversation between Boston National Weather Service forecaster Robert Case and author Sebastian Junger.
The 1804 New England hurricane was the first tropical cyclone in recorded history known to have produced snowfall. An unusual late-season storm in 1804, it yielded vast amounts of snow, rain, and powerful winds across the northeastern United States. Prior to its approach towards the East Coast of the United States, it passed through the Caribbean Sea on October 4, and later emerged near Georgetown, South Carolina. By early on October 9, a trough near the Virginia Capes turned the disturbance toward New England. Soon thereafter, the hurricane's abundant moisture clashed with an influx of cold Canadian air, leading to the deepening of the resulting pressure gradient and provoking inland intensification. While situated over Massachusetts, it attained its peak intensity of 110 mph (175 km/h), undergoing an extratropical transition. Even as it drifted towards the Canadian maritimes, consequently gradually weakening, precipitation persisted for another two days before the snowstorm finally subsided on October 11.
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of producing anything from cloudiness and mild showers to severe gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale (synoptic) low pressure weather systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, about the center of the cyclone.
Explosive cyclogenesis is the rapid deepening of an extratropical cyclonic low-pressure area. The change in pressure needed to classify something as explosive cyclogenesis is latitude dependent. For example, at 60° latitude, explosive cyclogenesis occurs if the central pressure decreases by 24 millibars (0.71 inHg) or more in 24 hours. This is a predominantly maritime, winter event, but also occurs in continental settings. This process is the extratropical equivalent of the tropical rapid deepening. Although their cyclogenesis is entirely different from that of tropical cyclones, bomb cyclones can produce winds of 74 to 95 mph, the same order as the first categories of the Saffir–Simpson scale, and yield heavy precipitation. Even though only a minority of bomb cyclones become this strong, some weaker ones can also cause significant damage.
Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. These vary depending on the latitude, altitude, topography, and atmospheric conditions. High winds, hail, excessive precipitation, and wildfires are forms and effects, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal phenomena include blizzards (snowstorms), ice storms, and duststorms.
Robert Allen "Bob" Case was a meteorologist who worked for the National Weather Service (NWS) for 28 years. Over the course of his career, he worked in NWS various offices, developing a diverse background in various types of weather forecasting, including a lengthy stint as a hurricane forecaster. He is best known for inspiring the naming of the 1991 Perfect Storm as The Perfect Storm.
The following outline is provided as an overview of and topical guide to the field of Meteorology.
Hurricane Grace was a short-lived Category 2 hurricane that contributed to the formation of the powerful 1991 Perfect Storm. Forming on October 26, Grace initially had subtropical origins, meaning it was partially tropical and partially extratropical in nature. It became a tropical cyclone on October 27, and ultimately peaked with winds of 105 mph (165 km/h). The storm had minor effects on the island of Bermuda as it passed to the south. A developing extratropical storm to the north turned Grace eastward; the hurricane was eventually absorbed into the large circulation of the larger low-pressure system. Fed by the contrast between cold air to the northwest and warm air from the remnants of Grace, this storm became a large and powerful nor'easter that caused extremely high waves and resulted in severe coastal damage along the East Coast of the United States.
Hybrid low may refer to a number of different meteorological depressions:
Winter storm naming in the United States has been used sporadically since the mid-1700s in various ways to describe historical winter storms. These names have been coined using schemes such as the days of the year that the storm impacted or noteworthy structures that the storm had damaged and/or destroyed. In the 2010s, winter storm naming became controversial with The Weather Channel coming up with its own list of names for winter storms similar to that of hurricanes. The marketing of weather became a big part of media revenue by the 1990s. Various other media outlets soon followed The Weather Channel with their own naming lists. Most government and research meteorologists argue that winter storms can reform more than once, making the process of naming them both difficult and redundant. The United States National Weather Service (NWS) has refrained from commenting on the system and stated that they do not name winter storms.
The Miller classification is a technique that meteorologists use to classify nor'easters. The system splits nor'easters into five categories: Miller A, Miller B, Miller C, Miller D, and Miller E; the classification system initially started out with the first two categories. The system was derived by meteorologist and researcher J.E. Miller in 1946,.
