Alberta is a western province of Canada. With an estimated population of 4,067,175 as of 2016 census, it is Canada's fourth most populous province and the most populous of Canada's three prairie provinces, its area is about 660,000 square kilometres. Alberta and its neighbour Saskatchewan were districts of the Northwest Territories until they were established as provinces on September 1, 1905; the premier has been Rachel Notley since May 2015. Alberta is bounded by the provinces of British Columbia to the west and Saskatchewan to the east, the Northwest Territories to the north, the U. S. state of Montana to the south. Alberta is one of three Canadian provinces and territories to border only a single U. S. state and one of only two landlocked provinces. It has a predominantly humid continental climate, with stark contrasts over a year. Alberta's capital, Edmonton, is near the geographic centre of the province and is the primary supply and service hub for Canada's crude oil, the Athabasca oil sands and other northern resource industries.
About 290 km south of the capital is the largest city in Alberta. Calgary and Edmonton centre Alberta's two census metropolitan areas, both of which have populations exceeding one million, while the province has 16 census agglomerations. Tourist destinations in the province include Banff, Drumheller, Sylvan Lake and Lake Louise. Alberta is named after the fourth daughter of Queen Victoria. Princess Louise was the wife of Marquess of Lorne, Governor General of Canada. Lake Louise and Mount Alberta were named in her honour. Alberta, with an area of 661,848 km2, is the fourth-largest province after Quebec and British Columbia. To the south, the province borders on the 49th parallel north, separating it from the U. S. state of Montana, while to the north the 60th parallel north divides it from the Northwest Territories. To the east, the 110th meridian west separates it from the province of Saskatchewan, while on the west its boundary with British Columbia follows the 120th meridian west south from the Northwest Territories at 60°N until it reaches the Continental Divide at the Rocky Mountains, from that point follows the line of peaks marking the Continental Divide in a southeasterly direction until it reaches the Montana border at 49°N.
The province extends 660 km east to west at its maximum width. Its highest point is 3,747 m at the summit of Mount Columbia in the Rocky Mountains along the southwest border while its lowest point is 152 m on the Slave River in Wood Buffalo National Park in the northeast. With the exception of the semi-arid steppe of the south-eastern section, the province has adequate water resources. There are numerous lakes used for swimming, fishing and a range of water sports. There are three large lakes, Lake Claire in Wood Buffalo National Park, Lesser Slave Lake, Lake Athabasca which lies in both Alberta and Saskatchewan; the longest river in the province is the Athabasca River which travels 1,538 km from the Columbia Icefield in the Rocky Mountains to Lake Athabasca. The largest river is the Peace River with an average flow of 2161 m3/s; the Peace River originates in the Rocky Mountains of northern British Columbia and flows through northern Alberta and into the Slave River, a tributary of the Mackenzie River.
Alberta's capital city, Edmonton, is located at about the geographic centre of the province. It is the most northerly major city in Canada, serves as a gateway and hub for resource development in northern Canada; the region, with its proximity to Canada's largest oil fields, has most of western Canada's oil refinery capacity. Calgary is about 280 km south of Edmonton and 240 km north of Montana, surrounded by extensive ranching country. 75% of the province's population lives in the Calgary–Edmonton Corridor. The land grant policy to the railroads served as a means to populate the province in its early years. Most of the northern half of the province is boreal forest, while the Rocky Mountains along the southwestern boundary are forested; the southern quarter of the province is prairie, ranging from shortgrass prairie in the southeastern corner to mixed grass prairie in an arc to the west and north of it. The central aspen parkland region extending in a broad arc between the prairies and the forests, from Calgary, north to Edmonton, east to Lloydminster, contains the most fertile soil in the province and most of the population.
Much of the unforested part of Alberta is given over either to grain or to dairy farming, with mixed farming more common in the north and centre, while ranching and irrigated agriculture predominate in the south. The Alberta badlands are located in southeastern Alberta, where the Red Deer River crosses the flat prairie and farmland, features deep canyons and striking landforms. Dinosaur Provincial Park, near Brooks, showcases the badlands terrain, desert flora, remnants from Alberta's past when dinosaurs roamed the lush landscape. Alberta has a humid continental climate with cold winters; the province is open to cold arctic weather systems from the north, which produce cold conditions in winter. As the fronts between the air masses shift north and south across Alberta, the temperature can change rapidly. Arctic
A tornado warning is an alert issued by national weather forecasting agencies to warn the public that severe thunderstorms with tornadoes are imminent or occurring. It can be issued after a tornado, funnel cloud and rotation in the clouds has been spotted by the public, storm chasers, emergency management or law enforcement; when this happens, the tornado sirens may sound in that area if any sirens are present, informing people that a tornado has been sighted or may be forming nearby. The issuance of a tornado warning indicates, it is a higher level of alert than a tornado watch, but it can be surpassed by an higher alert known as a tornado emergency or Particularly Dangerous Situation warning. The first official tornado forecast – and tornado warning – was made by United States Air Force Capt. Robert C. Miller and Major Ernest Fawbush, on March 25, 1948; the first such forecast came after the events that transpired five days earlier on March 20, 1948. S. Weather Bureau surface maps and upper-air charts that failed to note atmospheric instability and moisture content present over Oklahoma that would be suitable for producing thunderstorm activity, erroneously forecasting dry conditions for that night.
Thunderstorms soon developed southwest of Oklahoma City, at 9:30 p.m. forecasters from Will Rogers Airport sent a warning to Tinker that the storm encroaching the city was producing wind gusts of 92 miles per hour and a "Tornado South on Ground Moving NE!" Base personnel received an alert written by the Staff Sarg. on duty with Miller, minutes before the twister struck Tinker several minutes around 10:00 p.m. damaging several military aircraft that could not be secured in time before it crossed the base grounds. Following an inquiry the next day before a tribunal of five generals who traveled to Tinker from Washington, D. C. who ruled that the March 20 tornado was an "act of God not forecastable given the present state of the art", base commander Gen. Fred Borum tasked Miller and Fawbush to follow up on the board's suggestion to consider methods of forecasting tornadic thunderstorms. Over the next three days and Fawbush studied reports and charts from previous tornado events to determine the atmospheric conditions favorable for the development of tornadic activity, in an effort to predict such events with some degree of accuracy.
At the time, there had not been studies on. Miller and Fawbush's findings on atmospheric phenomenon present in past outbreaks would aid in their initial forecast, as the day's surface and upper-air analysis charts determined the same conditions present on March 20 were present on the 25th, concluded that central Oklahoma would have the highest risk for tornadoes during the late-afternoon and evening. Borum, who had put together a severe weather safety plan for base personnel suggested that Miller and Fawbush issue a severe thunderstorm forecast, asked the men if they would issue a tornado forecast based on the similarities between the conditions that produced the tornado which hit the base five days earlier, which they were reluctant to do. Fawbush wrote the forecast message that Miller would type and issued it to base operations at 2:50 p.m. as thunderstorms were approaching from North Texas. Defying the high odds of two tornadoes hitting the same area in five days, one hit the Tinker campus around 6:00 p.m. to the surprise of Miller, who found out about the storm via a radio report.
Miller and Fawbush would not put out another tornado forecast until March 25, 1949, when they predicted tornadic activity would occur in southeastern Oklahoma. Miller and Fawbush soon would distribute their tornado forecasts to the American Red Cross and Oklahoma Highway Patrol, after giving William Maughan, chief meteorologist at the U. S. Weather Bureau's Oklahoma City office, permission to relay their forecasts to those agencies; the relative accuracy of the forecasts restarted a debate over their reliability and whether military or civilian agencies should have jurisdiction over the issuance of weather warnings. The USAF had pioneered tornado forecasting and tornado warnings, although John P. Finley had developed the first experimental tornado forecasts in 1885, before he and other officials with the agency were prohibited by the United States Signal Service's weather service from using the word "tornado" in forecasts two years directing Finley to instead reference "severe local storms", a move motivated by concerns by businessmen in the Great Plains that Finley's forecasts would hurt economic development if potential investors believed their areas were tornado-prone.
This position on tornado forecasting would be shared with the U. S. Weather Bureau after it was formation in 1890, fearing that it would incite panic among the public if tornadoes were predicted to occur.
Inch of mercury
Inch of mercury is a unit of measurement for pressure. It is still used for barometric pressure in weather reports and aviation in the United States, it is the pressure exerted by a column of mercury 1 inch in height at the standard acceleration of gravity. Conversion to metric units depends on the temperature of mercury, hence its density. Aircraft altimeters measure the relative pressure difference between the lower ambient pressure at altitude and a calibrated reading on the ground. Within the United States and Canada, these readings are provided in inches of mercury. Ground readings vary with weather and along the route of the aircraft as it travels, so current readings are relayed periodically by air traffic control. Aircraft operating at higher altitudes set their barometric altimeters to a standard pressure of 29.92 inHg or 1013.25 hPa regardless of the actual sea level pressure. The resulting altimeter readings are known as flight levels. Piston engine aircraft with constant-speed propellers use inches of mercury to measure manifold pressure, indicative of engine power produced.
In automobile racing United States Auto Club and Champ Car Indy car racing, inches of mercury was the unit used to measure turbocharger inlet pressure. However, the inch of mercury is still used today in car performance modification to measure the amount of vacuum within the engine's intake manifold; this can be seen on boost/vacuum gauges. In air conditioning and refrigeration, inHg is used to describe "inches of mercury vacuum", or pressures below ambient atmospheric pressure, for recovery of refrigerants from air conditioning and refrigeration systems, as well as for leak testing of systems while under a vacuum, for dehydration of refrigeration systems; the low-side gauge in a refrigeration gauge manifold indicates pressures below ambient in "inches of mercury vacuum", down to a 30 inHg vacuum. Inches of mercury is used in automotive cooling system vacuum test and fill tools. A technician will use this tool to remove air from modern automotive cooling systems, test the systems ability to hold vacuum and subsequently refill using the vacuum as suction for the new coolant.
Typical minimum vacuum values are between 27 inHg. Inches of mercury was the usual unit of pressure measurement in railway vacuum brakes. Torr Bar Mercury barometer
Edmonton Metropolitan Region
The Edmonton Metropolitan Region commonly referred to as the Alberta Capital Region, Greater Edmonton or Metro Edmonton, is a conglomeration of municipalities centred on Alberta's provincial capital of Edmonton. The EMR's known boundaries are coincident with those of the Edmonton census metropolitan area as delineated by Statistics Canada. However, its boundaries are defined differently for Edmonton Metropolitan Region Board administrative purposes; the EMR is considered a major gateway to northern Alberta and the Canadian North for many companies, including airlines and oil/natural gas exploration. Located within central Alberta and at the northern end of the Calgary–Edmonton Corridor, the EMR is the northernmost metropolitan area in Canada; the Edmonton CMA includes the following 35 census subdivisions: six cities. The Edmonton CMA is the largest CMA in Canada by area at 9,426.73 km2. In the 2016 Census, it had a population of 1,321,426, making it the sixth largest CMA in Canada by population.
The Edmonton CMA comprises the majority of Statistics Canada's Division No. 11 in Alberta. A fragmentation in regional cooperation and partnership has long played a divisive role within the EMR. Edmonton was frustrated that its surrounding municipalities were receiving an increased tax base for major industrial development, while not contributing to Edmonton's burden to maintain and build new infrastructure within Edmonton used by the residents and businesses of the surrounding municipalities. After pulling out of the Alberta Capital Region Alliance, Edmonton lobbied the provincial government to establish some form of regional government that would be more effective in fostering regional cooperation between it and its surrounding municipalities; as a result, Premier Ed Stelmach announced in December 2007 that a governing board would be established for Edmonton's Capital Region. Four months the Capital Region Board was formed on April 15, 2008 with the passing of the Capital Region Board Regulation by Order in Council 127/2008 under the authority of the Municipal Government Act.
On October 26, 2017, the Capital Region Board was renamed to the Edmonton Metropolitan Region Board. The CRB was established with 25 participating or member municipalities – 23 of which were within the Edmonton CMA and two of which were outside the CMA; the number of member municipalities was reduced to 24 on September 10, 2010 after the Village of New Sarepta dissolved to hamlet status under the jurisdiction of Leduc County on September 1, 2010. Concurrent with the CRB's name change to the EMRB in October 2017, municipal membership decreased from 24 to 13 to include only those municipalities with a population of 5,000 or more. More the EMRB includes: six cities. Under the CRB Regulation, the CRB was tasked with preparing a growth plan to cover land use, intermunicipal transit and geographic information services components. In March, 2010, Growing Forward: The Capital Region Growth Plan, consisting of individual plans for these four components and two addenda, was approved by the Government of Alberta.
The CRGP includes a employment forecast for the Capital Region. With a base population of 1.12 million in 2009, the CRB has forecasted the population of the Capital Region to reach 1.31 million by 2019. However, the 2019 population estimate was reached and exceeded by 2014; the CRGP designates priority growth areas and cluster country residential areas within the Capital Region. The following is a list of municipalities in the Edmonton CMA, with those that are members of the EMRB indicated accordingly. ^ Strathcona County's 2016 federal census population of 98,044 includes 70,618 in the Sherwood Park urban service area. ^ The combined Wabamun 133A and 133B population of 1,622 includes 1,592 in Wabamun 133A and 30 in Wabamun 133B. Major industrial areas within the ECR include the northwest and Clover Bar industrial areas in Edmonton, Nisku Industrial Business Park in Leduc County, Acheson Industrial Area in Parkland County, Refinery Row in Strathcona County, Alberta's Industrial Heartland spanning portions of Sturgeon County, Strathcona County, Lamont County and Fort Saskatchewan.
At the moment, two more major industrial areas are in the final stages of establishment. The establishment of the Horse Hills industrial area in northeast Edmonton is in the final planning stages, while Edmonton Airports is planning its inland port development under the Port Alberta initiative at the Edmonton International Airport within Leduc County. Calgary-Edmonton Corridor Calgary Metropolitan Region Edmonton Metropolitan Region Board Edmo
The bar is a metric unit of pressure, but is not approved as part of the International System of Units. It is defined as equal to 100,000 Pa, less than the current average atmospheric pressure on Earth at sea level; the bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, a founder of the modern practice of weather forecasting. The International Bureau of Weights and Measures lists the bar as one of the "non-SI units should have the freedom to use", but has declined to include it among the "Non-SI units accepted for use with the SI"; the bar has been recognised in countries of the European Union since 2004. The US National Institute of Standards and Technology deprecates its use except for "limited use in meteorology" and lists it as one of several units that "must not be introduced in fields where they are not presently used"; the International Astronomical Union lists it under "Non-SI units and symbols whose continued use is deprecated". Units derived from the bar include the megabar, decibar and millibar.
The notation bar, though deprecated by various bodies, represents gauge pressure, i.e. pressure in bars above ambient or atmospheric pressure. The bar is defined using the SI derived unit, pascal: 1 bar ≡ 100,000 Pa ≡ 100,000 N/m2. Thus, 1 bar is equal to: 1,000,000 Ba. Notes: 1 millibar = 1 one-thousandth bar, or 1×10−3 bar 1 millibar = 1 hectopascal; the word bar has its origin in the Greek word βάρος, meaning weight. The unit's official symbol is bar. Between 1793 and 1795, the word bar was used for a unit of weight in an early version of the metric system. Atmospheric air pressure is given in millibars, where standard atmospheric pressure at sea level is defined as 1013.25 mbar, 101.325 kPa, 1.01325 bar, about 14.7 pounds per square inch. Despite the millibar not being an SI unit and weather reporters worldwide have long measured air pressure in millibars as the values are convenient. After the advent of SI units, some meteorologists began using hectopascals which are numerically equivalent to millibars.
For example, the weather office of Environment Canada uses kilopascals and hectopascals on their weather maps. In contrast, Americans are familiar with the use of the millibar in US reports of hurricanes and other cyclonic storms. In fresh water, there is an approximate numerical equivalence between the change in pressure in decibars and the change in depth from the water surface in metres. An increase of 1 decibar occurs for every 1.019716 m increase in depth. In sea water with respect to the gravity variation, the latitude and the geopotential anomaly the pressure can be converted into metres' depth according to an empirical formula; as a result, decibars are used in oceanography. Many engineers worldwide use the bar as a unit of pressure because, in much of their work, using pascals would involve using large numbers. In measurement of vacuum and in vacuum engineering, residual pressures are given in millibar, although torr or millimeter of mercury were common. Engineers that specialize in technical safety for offshore petrochemical facilities would be expected to refer to explosion loads in units of bar or bars.
A bar is a convenient unit of measure for pressures generated by low frequency vapor cloud explosions that are considered as part of accidental loading risk studies. In the automotive field, turbocharger boost is described in bars outside the USA. Tire pressure is specified in bar. Unicode has characters for "mb" and "bar", but they exist only for compatibility with legacy Asian encodings and are not intended to be used in new documents; the kilobar, equivalent to 100 MPa, is used in geological systems in experimental petrology. "Bar" and "bara" are sometimes used to indicate absolute pressures and "bar" and "barg" for gauge pressures. This usage is deprecated and fuller descriptions such as "gauge pressure of 2 bar" or "2-bar gauge" are recommended. Atmospheric pressure Centimetre of water Conversion of units Meteorology Metric prefix Orders of magnitude Pressure measurement This article incorporates material from the Citizendium article "Bar", licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License but not under the GFDL.
Official SI website: Table 8. Non-SI units accepted for use with the SI US government atmospheric pressure map showing atmospheric pressure in mbar
Edmonton is the capital city of the Canadian province of Alberta. Edmonton is on the North Saskatchewan River and is the centre of the Edmonton Metropolitan Region, surrounded by Alberta's central region; the city anchors the north end of what Statistics Canada defines as the "Calgary–Edmonton Corridor". The city had a population of 932,546 in 2016, making it Alberta's second-largest city and Canada's fifth-largest municipality. In 2016, Edmonton had a metropolitan population of 1,321,426, making it the sixth-largest census metropolitan area in Canada. Edmonton is North America's northernmost metropolitan area with a population over one million. A resident of Edmonton is known as an Edmontonian. Edmonton's historic growth has been facilitated through the absorption of five adjacent urban municipalities in addition to a series of annexations through 1982, the annexation of 8,260 ha of land from Leduc County and the city of Beaumont on January 1, 2019. Known as the "Gateway to the North", the city is a staging point for large-scale oil sands projects occurring in northern Alberta and large-scale diamond mining operations in the Northwest Territories.
Edmonton is a cultural and educational centre. It hosts a year-round slate of festivals, reflected in the nickname "Canada's Festival City", it is home to North America's largest mall, West Edmonton Mall, Fort Edmonton Park, Canada's largest living history museum. The earliest known inhabitants arrived in the area, now Edmonton around 3,000 BC and as early as 12,000 BC when an ice-free corridor opened as the last glacial period ended and timber and wildlife became available in the region. In 1754, Anthony Henday, an explorer for the Hudson's Bay Company, may have been the first European to enter the Edmonton area, his expeditions across the Canadian Prairies were to seek contact with the aboriginal population for establishing the fur trade, as the competition was fierce between the Hudson's Bay Company and the North West Company. By 1795, Fort Edmonton was established on the river's north bank as a major trading post for the Hudson's Bay Company; the new fort's name was suggested by John Peter Pruden after Edmonton, the hometown of both the HBC deputy governor Sir James Winter Lake, Pruden.
In 1876, Treaty 6, which includes what is now Edmonton, was signed between the Aboriginal peoples in Canada and Queen Victoria as Queen of Canada, as part of the Numbered Treaties of Canada. The agreement includes the Plains and Woods Cree and other band governments of First Nations at Fort Carlton, Fort Pitt, Battle River; the area covered by the treaty represents most of the central area of the current provinces of Saskatchewan and Alberta. The coming of the Canadian Pacific Railway to southern Alberta in 1885 helped the Edmonton economy, the 1891 building of the Calgary and Edmonton Railway resulted in the emergence of a railway townsite on the river's south side, across from Edmonton; the arrival of the CPR and the C&E Railway helped bring settlers and entrepreneurs from eastern Canada, Europe, U. S. and other parts of the world. The Edmonton area's fertile soil and cheap land attracted settlers, further establishing Edmonton as a major regional commercial and agricultural centre; some people participating in the Klondike Gold Rush passed through South Edmonton/Strathcona in 1897.
Strathcona was North America's northernmost railway point, but travel to the Klondike was still difficult for the "Klondikers," and a majority of them took a steamship north to the Yukon from Vancouver, British Columbia. Incorporated as a town in 1892 with a population of 700 and as a city in 1904 with a population of 8,350, Edmonton became the capital of Alberta when the province was formed a year on September 1, 1905. In November 1905, the Canadian Northern Railway arrived in Edmonton. During the early 1900s, Edmonton's rapid growth led to speculation in real estate. In 1912, Edmonton amalgamated with the City of Strathcona, south of the North Saskatchewan River. Just before World War I, the boom ended, the city's population declined from more than 72,000 in 1914 to less than 54,000 only two years later. Many impoverished families moved to subsistence farms outside the city, while others fled to greener pastures in other provinces. Recruitment to the army during the war contributed to the drop in population.
Afterwards, the city recovered in population and economy during the 1920s and 1930s and took off again during and after World War II. The Edmonton City Centre Airport opened in 1929. Named Blatchford Field in honour of former mayor Kenny Blatchford, pioneering aviators such as Wilfrid R. "Wop" May and Max Ward used Blatchford Field as a major base for distributing mail and medicine to Northern Canada. World War II saw Edmonton become a major base for the construction of the Alaska Highway and the Northwest Staging Route; the airport was closed in November 2013. In 1892 Edmonton was incorporated as a town; the first mayor was Matthew McCauley, who established the first school board in Edmonton and Board of Trade and a municipal police service. Due to mayor McCauley's good relationship with the federal Liberals this helped Edmonton to maintain political prominence over Strathcona, a rival settlement on the south bank of the North Saskatche
A tornado is a rotating column of air, in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. The windstorm is referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, they are visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 110 miles per hour, are about 250 feet across, travel a few miles before dissipating; the most extreme tornadoes can attain wind speeds of more than 300 miles per hour, are more than two miles in diameter, stay on the ground for dozens of miles. Various types of tornadoes include the multiple vortex tornado and waterspout. Waterspouts are characterized by a spiraling funnel-shaped wind current, connecting to a large cumulus or cumulonimbus cloud.
They are classified as non-supercellular tornadoes that develop over bodies of water, but there is disagreement over whether to classify them as true tornadoes. These spiraling columns of air develop in tropical areas close to the equator and are less common at high latitudes. Other tornado-like phenomena that exist in nature include the gustnado, dust devil, fire whirl, steam devil. Tornadoes occur most in North America in central and southeastern regions of the United States colloquially known as tornado alley, as well as in Southern Africa and southeast Europe and southeastern Australia, New Zealand and adjacent eastern India, southeastern South America. Tornadoes can be detected before or as they occur through the use of Pulse-Doppler radar by recognizing patterns in velocity and reflectivity data, such as hook echoes or debris balls, as well as through the efforts of storm spotters. There are several scales for rating the strength of tornadoes; the Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale.
An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers; the similar TORRO scale ranges from a T0 for weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data and ground swirl patterns may be analyzed to determine intensity and assign a rating; the word tornado comes from the Spanish word tornado. Tornadoes opposite phenomena are the derechoes. A tornado is commonly referred to as a "twister", is sometimes referred to by the old-fashioned colloquial term cyclone; the term "cyclone" is used as a synonym for "tornado" in the often-aired 1939 film The Wizard of Oz. The term "twister" is used in that film, along with being the title of the 1996 tornado-related film Twister. A tornado is "a violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, visible as a funnel cloud".
For a vortex to be classified as a tornado, it must be in contact with both the ground and the cloud base. Scientists have not yet created a complete definition of the word. Tornado refers to the vortex of wind, not the condensation cloud. A tornado is not visible; this results in the formation of a visible funnel condensation funnel. There is some disagreement over the definition of a condensation funnel. According to the Glossary of Meteorology, a funnel cloud is any rotating cloud pendant from a cumulus or cumulonimbus, thus most tornadoes are included under this definition. Among many meteorologists, the'funnel cloud' term is defined as a rotating cloud, not associated with strong winds at the surface, condensation funnel is a broad term for any rotating cloud below a cumuliform cloud. Tornadoes begin as funnel clouds with no associated strong winds at the surface, not all funnel clouds evolve into tornadoes. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.
A single storm will produce more than one tornado, either or in succession. Multiple tornadoes produced by the same storm cell are referred to as a "tornado family". Several tornadoes are sometimes spawned from the same large-scale storm system. If there is no break in activity, this is considered a tornado outbreak. A period of several successive days with tornado outbreaks in the same general area is a tornado outbreak sequence called an extended tornado outbreak. Most tornadoes take on the appearance of a narrow funnel, a few hundred yards across, with a small cloud of debris near the ground. Tornadoes may