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In meteorology, a heat burst is a rare atmospheric phenomenon characterized by gusty winds along with a rapid increase in temperature and decrease in dew point (moisture). Heat bursts typically occur during night-time and are associated with decaying thunderstorms.
Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It was not until after the elucidation of the laws of physics and more particularly, the development of the computer, allowing for the automated solution of a great many equations that model the weather, in the latter half of the 20th century that significant breakthroughs in weather forecasting were achieved. An important domain of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water.
Temperature is a physical quantity expressing hot and cold. It is measured with a thermometer calibrated in one or more temperature scales. The most commonly used scales are the Celsius scale, Fahrenheit scale, and Kelvin scale. The kelvin is the unit of temperature in the International System of Units (SI), in which temperature is one of the seven fundamental base quantities. The Kelvin scale is widely used in science and technology.
The dew point is the temperature to which air must be cooled to become saturated with water vapor. When further cooled, the airborne water vapor will condense to form liquid water (dew). When air cools to its dew point through contact with a surface that is colder than the air, water will condense on the surface. When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed rather than dew. The measurement of the dew point is related to humidity. A higher dew point means there will be more moisture in the air.
Although this phenomenon is not fully understood, it is theorized that the event is caused when rain evaporates (virga) into a parcel of cold, dry air high in the atmosphere- making the air denser than its surroundings.The parcel descends rapidly, warming due to compression, overshoots its equilibrium level and reaches the surface, similar to a downburst.
In meteorology, a virga is an observable streak or shaft of precipitation falling from a cloud that evaporates or sublimates before reaching the ground. A shaft of precipitation that does not evaporate before reaching the ground is a precipitation shaft. At high altitudes the precipitation falls mainly as ice crystals before melting and finally evaporating; this is often due to compressional heating, because the air pressure increases closer to the ground. It is very common in deserts and temperate climates. In North America, it is commonly seen in the Western United States and the Canadian Prairies. It is also very common in the Middle East, Australia, and North Africa.
In meteorology, the equilibrium level (EL), or level of neutral buoyancy (LNB), or limit of convection (LOC), is the height at which a rising parcel of air is at the same temperature as its environment.
A downburst is a strong ground-level wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the point of contact at ground level. Often producing damaging winds, it may be confused with a tornado, where high-velocity winds circle a central area, and air moves inward and upward; by contrast, in a downburst, winds are directed downward and then outward from the surface landing point.
Recorded temperatures during heat bursts have reached well above 40 °C (104 °F ), sometimes rising by 10 °C (18 °F) or more within only a few minutes. More extreme events have also been documented, where temperatures have been reported to exceed 50 °C (122 °F). However, such extreme events have never been officially verified. Heat bursts are also characterized by extremely dry air and are sometimes associated with very strong, even damaging, winds.
The Celsius scale, also known as the centigrade scale, is a temperature scale used by the International System of Units (SI). As an SI derived unit, it is used by all countries except the United States, the Bahamas, Belize, the Cayman Islands and Liberia. It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale. The degree Celsius can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures or an uncertainty. Before being renamed to honor Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps.
The Fahrenheit scale is a temperature scale based on one proposed in 1724 by Dutch–German–Polish physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit as the unit. Several accounts of how he originally defined his scale exist. The lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from equal parts of ice, water and salt. Further limits were established as the melting point of ice (32 °F) and his best estimate of the average human body temperature. The scale is now usually defined by two fixed points: the temperature at which water freezes into ice is defined as 32 °F, and the boiling point of water is defined to be 212 °F, a 180 °F separation, as defined at sea level and standard atmospheric pressure.
Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the Sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn. Winds have various aspects, an important one being its velocity ; another the density of the gas involved; another its energy content or wind energy. Wind is also a great source of transportation for seeds and small birds; with time things can travel thousands of miles in the wind.
In general, heat bursts occur during the late spring and summer seasons. During these times, thunderstorms tend to generate day heating and lose their main energy during the evening hours.Due to a potential temperature increase, heat bursts normally occur at night; however, heat bursts have also been recorded to occur during the daytime. Heat bursts have lasted for times spanning from a couple of minutes to several hours. The rare phenomenon is usually accompanied by strong gusty winds, extreme temperature changes, and an extreme decrease in humidity. They occur near the end of a weakening thunderstorm cluster. Dry air and a low-level inversion are also present during the storm.
As the thunderstorm starts to dissipate, the layer of clouds start to rise. After the layer of clouds have risen, a rain-cooled layer remains. The cluster shoots a burst of unsaturated air down towards the ground. In doing so, the system loses all of its up-draft related fuel. °C per 1000 meters (5.5 °F per 1000 feet) of descent. The warm air from the cluster replaces the cool air on the ground. The effect is similar to someone blowing down on a puddle of water. On 4 March 1990, the National Weather Service in Goodland, Kansas detected a system that had weakening, light rain showers, and snow showers. It was followed by gusty winds and a temperature increase. A heat burst was being observed. The detection proved that heat bursts can occur in both summer months and winter months. The occurrence also proved that a weakening thunderstorm was not needed in the development of heat bursts.The raindrops begin to evaporate into dry air, which emphasizes the effects of the heat bursts. As the unsaturated air descends, the air pressure increases. The descending air parcel warms at the dry adiabatic lapse rate of approximately 10
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, changes with altitude. Lapse rate arises from the word lapse, in the sense of a gradual change. It corresponds to the vertical component of the spatial gradient of temperature. Although this concept is most often applied to the Earth's troposphere, it can be extended to any gravitationally supported parcel of gas.
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1890 until it adopted its current name in 1970.
Goodland is a city in and the county seat of Sherman County, Kansas, United States. As of the 2010 census, the city population was 4,489. It was named after Goodland, Indiana. Goodland is home to Northwest Kansas Technical College.
The first step of forecasting and preparing for heat bursts is recognizing the events that come before heat bursts occur. Rain from a high convection cloud falls below cloud level and evaporates, cooling the air. Air parcels that are cooler than the surrounding environment fall. And lastly, temperature conversion mixed with a downdraft momentum continue downward until the air reaches the ground. The air parcels then become warmer than their environment. McPherson, Lane, Crawford, and McPherson Jr. researched the heat burst system at the Oklahoma Mesonet, which is owned by both the University of Oklahoma and Oklahoma State University. The purpose of their research was to discover any technological benefits and challenges in detecting heat bursts, document the time of day and year that heat bursts mostly occur, and to research the topography of where heat bursts mostly occur in Oklahoma. Scientists and meteorologists use archived data to manually study data that detected 390 potential heat burst days during a fifteen-year period. In studying the archived data, they observed that 58% of the potential days had dry-line passages, frontal passages or a temperature change. The temperature change was due to an increase in solar radiation in the hours of the morning or a daytime precipitation weather system. By studying the archived data, the scientists' have the ability to determine the beginning, peak and end of heat burst conditions. The peak of heat burst conditions is the maximum observed temperature. The beginning of the heat burst occurrence is the time when the air temperature began to increase without decreasing until after the heat burst. The end of the heat burst is when the system ceased to affect the temperature and dew point of the area. In addition to researching the life cycle and characteristics of heat bursts, a group of scientists concluded that the topography of Oklahoma coincided with the change in atmospheric moisture between northwest and southeast Oklahoma. An increase in convection normally occurs over the United States High Plains during the late spring and summer. They also concluded that a higher increase in convection develops if a mid-tropospheric lifting mechanism interacts with an elevated moist layer.
Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids, including molten rock (rheid). Convection includes sub-mechanisms of advection, and diffusion.
The Oklahoma Mesonet is a network of environmental monitoring stations designed to measure the environment at the size and duration of mesoscale weather events. The phrase "mesonet" is a portmanteau of the words mesoscale and network. In meteorology, “mesoscale” refers to weather events that range in size from approximately 1 mile (1.6 km) to 150 miles (240 km) and can last from several minutes to several hours. Mesoscale events include thunderstorms, wind gusts, heat bursts, and dry lines. Without densely spaced weather observations, these mesoscale events might go undetected. In addition to surface weather observations, Oklahoma Mesonet stations also include environmental data such as on insolation and soil conditions, and some sites are co-located with wind profilers.
The University of Oklahoma (OU) is a public research university in Norman, Oklahoma. Founded in 1890, it had existed in Oklahoma Territory near Indian Territory for 17 years before the two became the state of Oklahoma. In Fall 2018 the university had 31,702 students enrolled, most at its main campus in Norman. Employing nearly 3,000 faculty members, the school offers 152 baccalaureate programs, 160 master's programs, 75 doctorate programs, and 20 majors at the first professional level. David Boren, a former U.S. Senator and Oklahoma Governor, served as the university's president from 1994 to 2018. James L. Gallogly succeeded Boren on July 1, 2018.
These are cases when temperatures over 56.7 °C (134.1 °F) (the highest officially confirmed in the World, in Death Valley, United States, 1913) were recorded during heat bursts.
Wind-chill or windchill is the lowering of body temperature due to the passing-flow of lower-temperature air.
A severe thunderstorm warning is issued by the National Weather Service when trained storm spotters or Doppler weather radar indicate that a thunderstorm is producing or will soon produce dangerously large hail or high winds, capable of causing significant damage. In the United States, severe thunderstorm warnings do not account for lightning, a significant hazard in any thunderstorm, or flooding caused by a thunderstorm's extreme rainfall. A similar warning is issued by Environment Canada's Meteorological Service of Canada from their offices in Vancouver, Edmonton, Toronto, Montreal and Dartmouth. Skywarn issues the severe thunderstorm warnings for the United Kingdom. Just as in the United States, lightning does not warrant a severe thunderstorm warning. In Australia, severe thunderstorm warnings are issued by the Bureau of Meteorology for all Australian states.
METAR is a format for reporting weather information. A METAR weather report is predominantly used by pilots in fulfillment of a part of a pre-flight weather briefing, and by meteorologists, who use aggregated METAR information to assist in weather forecasting.
The heat wave of 1995 derecho series are a series of derechos that occurred from July 11 through July 15, 1995 in the U.S. and Ontario, Canada. This weather event is among one of the least known about but still notable weather events that occurred during the 20th century.
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms. This article describes NWS terminology and related weather scales used by the agency. Some terms may be specific to certain cities or regions.
Kopperl is an unincorporated community in Bosque County, Texas, United States. It lies on the northwestern end of Lake Whitney, and has an estimated population of 225.
This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.
Launch commit criteria are the criteria which must be met in order for the countdown and launch of a space shuttle or other launch vehicle to continue. These criteria relate to safety issues and the general success of the launch, as opposed to supplemental data.
The Corn Belt derecho was a progressive derecho which affected a large area of the central United States on June 29, 1998. In the morning, thunderstorms, including a supercell, developed over South Dakota and tracked into central Iowa. As the thunderstorms reached central Iowa, a strong rear-inflow jet developed which caused the thunderstorm to take on a different characteristic, becoming a derecho. It traveled more than 600 miles in about ten hours, causing more than $125 million worth of widespread damage destruction, especially to crops, and was responsible for power outages to nearly a half a million people.
Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.
Automated airport weather stations are automated sensor suites which are designed to serve aviation and meteorological observing needs for safe and efficient aviation operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing in the United States and Canada and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings.
The tornado outbreak of February 10–11, 2009 occurred on February 10 and February 11, 2009, affecting portions of both the Central and Eastern United States. During the two-day period, 15 tornadoes touched down in seven states. Oklahoma was struck by six tornadoes, the most of any state. The first day of the outbreak produced the most tornadoes; the second brought mainly high wind damage and rain or snow in most of the Northeast.
A wake low, or wake depression, is a mesoscale low-pressure area which trails the mesoscale high following a squall line. Due to the subsiding warm air associated with the systems formation, clearing skies are associated with the wake low. Once difficult to detect in surface weather observations due to their broad spacing, the formation of mesoscale weather station networks, or mesonets, has increased their detection. Severe weather, in the form of high winds, can be generated by the wake low when the pressure difference between the mesohigh preceding it and the wake low is intense enough. When the squall line is in the process of decay, heat bursts can be generated near the wake low. Once new thunderstorm activity along the squall line concludes, the wake low associated with it weakens in tandem.
The climate of south-west England is classed as oceanic (Cfb) according to the Köppen climate classification. The oceanic climate is typified by cool winters with warmer summers and precipitation all year round, with more experienced in winter. Annual rainfall is about 1,000 millimetres (39 in) and up to 2,000 millimetres (79 in) on higher ground. Summer maxima averages range from 18 °C (64 °F) to 22 °C (72 °F) and winter minima averages range from 1 °C (34 °F) to 4 °C (39 °F) across the south-west. It is the second windiest area of the United Kingdom, the majority of winds coming from the south-west and north-east. Government organisations predict the area will experience a rise in temperature and become the hottest region in the United Kingdom.
The June 2012 Mid-Atlantic and Midwest derecho was one of the most destructive and deadly fast-moving severe thunderstorm complexes in North American history. The progressive derecho tracked across a large section of the Midwestern United States and across the central Appalachians into the mid-Atlantic states on the afternoon and evening of June 29, 2012, and into the early morning of June 30, 2012. It resulted in a total of 22 deaths, millions of power outages across the entire affected region, and a damage total of US $2.9 billion which exceeded that of all but the top 25 Atlantic tropical cyclones. The storm prompted the issuance of four separate severe thunderstorm watches by the Storm Prediction Center. A second storm in the late afternoon caused another watch to be issued across Iowa and Illinois.
Rawalpindi features a humid subtropical climate with long and hot summers, a monsoon and short, mild and wet winters. Its climate is classified as very similar to its twin city Islamabad, but the geographical location and extreme urbanization of Rawalpindi has led to weather and climatic conditions that are notably different from its twin. Rawalpindi's weather has historically been known to change rather quickly due to its proximity to Himalayas and the Pir Panjal Range. These mountains not only influence the weather of the city, but also provide great recreation during the hot months. Furthermore, Its warm comfortable mean annual temperature of 21.3 °C (70 °F) attracts people to live here permanently from all over Pakistan. The average annual rainfall is abundant at 1,246.8 millimetres (49.09 in), most of which falls in the monsoon season. However, frontal cloud bands also bring significant rainfall in the winter. In summers, June is the hottest with record maximum temperature at a blistering 48.3 °C (119 °F) recorded on 13 June 1953. On the other hand, January is the coldest month of the year when temperature can drop to a minimum −3.9 °C (25 °F) in the winter recorded on 17 January 1967. Throughout the year, Rawalpindi and Islamabad experience an average of about 90 thunderstorms, which is the highest frequency of thunderstorms in Punjab province of any plane station. In fact, most rainfall in the city is accompanied by a thunderstorm with peak activity experienced in August. Record rainfall was experienced in the year 2013 at a massive 1,988 millimetres (78.3 in) mostly due to an unusually wet monsoon season. On a typical day, the city hosts breezy afternoons, but usually calm to light breeze wind conditions are observed after midnight. The mean annual wind speed of Rawalpindi is roughly 10 kilometres per hour (6.2 mph) at 14 m height. Moreover, just a few kilometers southwest of Rawalpindi, the potential power generation has been identified by U.S. Aid to be between marginal to good at 50 m height.
2014 Pentecost weekend storms in Europe were a series of severe supercell storms affecting western Europe which followed a heatwave in early June 2014, resulting from a Spanish plume synoptic weather pattern. The weekend saw repeated convective storm development across an arc from southwest France towards Paris and on towards Belgium and northwest Germany, where warm air masses interacted with the cooler air brought in by an area of low pressure moving towards the continent from the Atlantic. Outbreaks of severe weather were reported from these storm developments with the worst damages occurring over the German state of North Rhine-Westphalia on 9 June, where the storm was described as one of the most violent in decades by the German weather service, this storm is also referred to as low pressure area "Ela" in some German media.
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