A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity. Country-by-country France In France, 14802 people&mdashmostly elderly&mdashdied from heat according to the country's largest funeral service The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. There is no universal definition of a heat wave;^[1] the term is relative to the usual weather in the area. Temperatures that people from a hotter climate consider normal can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of ^[2] The term is applied both to routine weather variations and to extraordinary spells of heat which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning. Hyperthermia, in its advanced state referred to as heat stroke or sunstroke, is an acute condition which occurs when the Body produces or absorbs more A power outage (also known as power cut, power failure, power loss, or blackout) is the loss of the Electricity supply to an The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort.

Contents 1 Definitions 2 Incidence 3 How they occur 3.1 Mortality 3.1.1 Underreporting and "Harvesting" effect 3.2 Psychological and sociological effects 3.3 Power outage 3.4 Wildfires 4 History 5 See also 6 Notes 7 External links

Definitions

The definition recommended by the World Meteorological Organization is when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C (9 °F), the normal period being 1961 - 1990. ^[3]

A formal, peer-reviewed definition from the Glossary of Meteorology is:^[4]

A period of abnormally and uncomfortably hot and usually humid weather. Peer review (also known as refereeing) is the process of subjecting an author's scholarly work research or Ideas to the scrutiny of others who are

To be a heat wave such a period should last at least one day, but conventionally it lasts from several days to several weeks. In 1900, A. T. Burrows more rigidly defined a “hot wave” as a spell of three or more days on each of which the maximum shade temperature reaches or exceeds 90 °F. More realistically, the comfort criteria for any one region are dependent upon the normal conditions of that region.

A heat storm is an extended heat wave. A Heat Storm, as defined by the California Energy Commission, is what most would refer to as a Heat wave. Heat storms occur when the temperature reaches 100 °F (38 °C) for three or more consecutive days over a wide area (tens of thousands of square miles).

In the Netherlands, a heat wave is defined as period of at least 5 consecutive days in which the maximum temperature in De Bilt exceeds 25 °C (77 °F), provided that on at least 3 days in this period the maximum temperature in De Bilt exceeds 30 °C (86 °F). The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands De Bilt is a municipality and a town in the Netherlands, in the province of Utrecht. [1]. This definition of a heat wave is also used in Belgium, Denmark, and Luxembourg. The Kingdom of Belgium is a Country in northwest Europe. It is a founding member of the European Union and hosts its headquarters as well as those The Kingdom of Denmark ( ˈd̥ænmɑɡ̊ (archaic ˈd̥anmɑːɡ̊ commonly known as Denmark, is a country in the Scandinavian region of northern Europe Luxembourg (Groussherzogtum Lëtzebuerg Grand-Duché de Luxembourg Großherzogtum Luxemburg is a small Landlocked country in Western Europe, bordered by

In the United States, definitions also vary by region; however, a heat wave is usually defined as a period of at least three consecutive days above 90 °F (32. The United States of America —commonly referred to as the 2 °C). [2] The National Weather Service criterion for the issuance of a heat advisory is when the heat index is expected to (or does) reach 105 °F (40. The National Weather Service ( NWS) once known as the Weather Bureau is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration This article describes the United States National Weather Service (NWS The heat index ( HI) is an index that combines Air Temperature and Relative humidity in an attempt to determine the human-perceived equivalent 6 °C) with a nighttime low temperature not below 80 °F (26. 7 °C), whereas an excessive heat warning is issued when a maximum heat index exceeding 115 °F (46. This article describes the United States National Weather Service (NWS 1 °C) with minimum 80 °F (26. 7 °C) is expected (or is occurring).

Incidence

Heat waves often occur during the Dog Days of summer; indeed the French term canicule, denoting the general phenomenon of a heat wave, derives from the Italian canicula applied to the star Sirius, also known as the "Dog Star. The phrase Dog Days or " the dog days of summer " refers to the hottest most sultry days of summer French ( français,) is a Romance language spoken around the world by 118 million people as a native language and by about 180 to 260 million people Italian ( or lingua italiana) is a Romance language spoken by about 63 million people as a First language, primarily in Italy. Sirius is the brightest star in the night sky with a visual Apparent magnitude of &minus1 "^[5]

Some regions of the globe are more susceptible to heat waves than others, such as Mediterranean-type climates with a summer dry spell which becomes much hotter than usual during certain years. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A Mediterranean climate is one that resembles the Climate of the lands in the Mediterranean Basin, which includes over half of the area with this climate type world-wide

How they occur

In the summer in warm climates, if there is an area of high pressure with little or no rain and clouds, there is nothing to protect the air and ground from being heated excessively. When large high pressure air is trapped, the ground and air will continue to heat and the heat wave will last longer.

The position of the jet stream is very important because the air on one side is hot while the other side is cold. Jet streams are fast flowing relatively narrow air currents found at the Tropopause, the transition between the Troposphere (where temperature decreases Heat waves are far more likely and more severe when you are on the hot side. Sometimes the jet stream does not move far enough to make many areas that normally get hot on the hot side; but sometimes many cold areas are made hot abnormally. The effects of El Niño and La Niña (opposite reaction to El Niño) can severely disrupt the positions of the jet streams. El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon

Large desert zones and dry areas are more likely to get extreme heat because there is rarely any high cloud cover with very low humidity, making it like a furnace.

The direction of the wind is a very important part of the reasons for heat waves, because this pushes hot air towards colder areas if they are going away from the deserts and equator. The higher the force of the wind as well as the distance they travel from the hotter to colder areas, generally means hotter weather.

Cities also get hotter because they generate heat from the use of power, usually by about 1-2 °C or so and experience very warm night time minimum temperatures putting further strain on energy demands.

Humidity also has a serious effect on how hot it feels but this does not make the actual temperature any hotter. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Heat Waves in Eastern North America and the British Isles are usually accompanied by high humidity, aggravating the heat index (one's discomfort), as opposed to the drier heat typically experienced during heat waves in continental Europe, Western North America or cities in Australia. The British Isles (Irish variously Na hOileáin Bhriotanacha, Oileáin Iarthair Eorpa, Éire agus an Bhreatain Mhór; Ellanyn Goaldagh Eileanan For a topic outline on this subject see List of basic Australia topics.

Perhaps the most well-known heat-related illness is hyperthermia, also known as heat stroke. Hyperthermia, in its advanced state referred to as heat stroke or sunstroke, is an acute condition which occurs when the Body produces or absorbs more Classic heat stroke occurs during periods of sustained high temperature and humidity. Sweating is absent from 84%-100% of those affected. Older adults, very young children, and those who are sick or overweight are at a higher risk for heat-related illness. The chronically ill and elderly are often taking prescription medications (e. g. , diuretics, anticholinergics, antipsychotics, and antihypertensives) that interfere with the body's ability to dissipate heat. A diuretic is any Drug that elevates the rate of urination ( Diuresis) An anticholinergic agent is a substance that blocks the Neurotransmitter acetylcholine in the central and the Peripheral nervous system. Antipsychotics are a group of Psychoactive drugs commonly but not exclusively used to treat Psychosis, which is typified by Schizophrenia. Antihypertensives are a class of drugs that are used in Medicine and Pharmacology to treat Hypertension (high blood pressure ^[6]

Heat edema presents as a transient swelling of the hands, feet, and ankles and is generally secondary to increased aldosterone secretion, which enhances water retention. Oedema (or Edema in American English formerly known as dropsy or hydropsy, is the increase of Interstitial fluid in any organ &mdash swelling Aldosterone is a hormone that causes the tubules of the kidneys to retain sodium and water Secretion is the process of segregating elaborating and releasing chemicals from a cell, or a secreted Chemical substance or amount of substance When combined with peripheral vasodilation and venous stasis, the excess fluid accumulates in the dependent areas of the extremities. In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel In Medicine, stasis means the state in which the normal flow of a body liquid stops for example the flow of Blood through vessels or of intestinal contents The heat edema usually resolves within several days after the patient becomes acclimated to the warmer environment. No treatment is required, although wearing support stocking and elevating the affected legs with help minimize the edema.

Heat rash, also known as prickly heat, is a maculopapular rash accompanied by acute inflammation and blocked sweat ducts. Miliaria (miliaria rubra sweat rash or prickly heat is a Skin disease marked by small and itchy Rashes Miliaria is a common ailment in hot and humid conditions A maculopapular rash is a medical term used to describe a unique type of Rash. Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens The sweat ducts may become dilated and may eventually rupture, producing small pruritic vesicles on an erythematous base. Erythema is redness of the Skin caused by Capillary congestion Heat rash affects areas of the body covered by tight clothing. If this continues for a duration of time it can lead to the development of chronic dermatitis or a secondary bacterial infection. Dermatitis is a Blanket term meaning any " Inflammation of the skin" (e The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have An infection is the detrimental Colonization of a host Organism by a foreign Species. Prevention is the best therapy. It is also advised to wear loose-fitting clothing in the heat. However, once heat rash has developed, the initial treatment involves the application of chlorhexidine lotion to remove any desquamated skin. Chlorhexidine is a chemical Antiseptic.It kills (is bactericidal to both Gram-positive and Gram-negative Microbes although it is less effective A lotion is a low- to medium- Viscosity, topical preparation intended for application to unbroken Skin; creams and gels have a higher viscosity Desquamation is the shedding of the outer layers of the Skin. The associated itching may be treated with topical or systemic antihistamines. If infection occurs a regimen of antibiotics is required. In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa

Heat cramps are painful, often severe, involuntary spasms of the large muscle groups used in strenuous exercise. Heat cramps are a form of Heat injury. Heat cramps are associated with cramping in the Abdomen, Arms and Calves. A spasm is a sudden involuntary contraction of a Muscle, a group of muscles or a hollow organ, or a similarly sudden Contraction of an Orifice Heat cramps tend to occur after intense exertion. They usually develop in people performing heavy exercise while sweating profusely and replenishing fluid loss with non-electrolyte containing water. This is believed to lead to hyponatremia that induces cramping in stressed muscles. Hyponatremia ( British: hyponatraemia) is an Electrolyte disturbance (disturbance of the salts in the blood in which the Sodium ( Natrium Rehydration with salt-containing fluids provides rapid relief. Rehydration is the replenishment of Water, or water and Electrolytes lost through Dehydration. Patients with mild cramps can be given oral . 2% salt solutions, while those with severe cramps require IV isotonic fluids. Intravenous therapy or IV therapy is the giving of Liquid substances directly into a Vein. The many sport drinks on the market are a good source of electrolytes and are readily accessible. A sports drink is a Beverage designed to help athletes rehydrate as well as replenish Electrolytes Carbohydrates, and other Nutrients An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium

Heat syncope is related to heat exposure that produces orthostatic hypotension. Heat syncope is another stage in the same process as Heat stroke, occurs under similar conditions as heat stroke and is not distinguished from the latter by some authorities Orthostatic hypotension (also known as postural hypotension, and colloquially as head rush or a dizzy spell) is a form of Hypotension in which This hypotension can precipitate a near-syncopal episode. Heat syncope is believed to result from intense sweating, which leads to dehydration, followed by peripheral vasodilation and reduced venous blood return in the face of decreased vasomotor control. Dehydration ( hypohydration) is the removal of Water ( hydro in ancient Greek) from an object Management of heat syncope consists of cooling and rehydration of the patient using oral rehydration therapy (sport drinks) or isotonic IV fluids. Oral rehydration therapy, (also called ORT, oral rehydration salts or solutions (ORS, oral electrolyte) is a simple cheap and effective People who experience heat syncope should avoid standing in the heat for long periods of time. They should move to a cooler environment and lie down if they recognize the initial symptoms. Wearing support stockings and engaging in deep knee-bending movements can help promote venous blood return.

Heat exhaustion is considered by experts to be the forerunner of heat stroke (hyperthermia). Hyperthermia, in its advanced state referred to as heat stroke or sunstroke, is an acute condition which occurs when the Body produces or absorbs more It may even resemble heat stroke, with the difference being that the neurologic function remains intact. Heat exhaustion is marked by excessive dehydration and electrolyte depletion. Symptoms may include headache, nausea, and vomiting, dizziness, tachycardia, malaise, and myalgia. A headache ( cephalalgia in medical terminology is a condition of pain in the Head; sometimes Neck or upper back pain may also be interpreted Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort Vomiting (also called throwing up, emesis) is the forceful expulsion of the contents of one's Stomach through the Mouth and sometimes the Many different terms are often used to describe what is collectively known as dizziness. Malaise is a feeling of general discomfort or uneasiness an "out of sorts" feeling often the first indication of an infection or other disease Myalgia means " Muscle Pain " and is a symptom of many diseases and disorders Definitive therapy includes removing patients from the heat and replenishing their fluids. Most patients will require fluid replacement with IV isotonic fluids at first. The salt content is adjusted as necessary once the electrolyte levels are known. After discharge from the hospital, patients are instructed to rest, drink plenty of fluids for 2 - 3 hours, and avoid the heat for several days. If this advice is not followed it may then lead to heat stroke.

One public health measure taken during heat waves is the setting-up of air-conditioned public cooling centers. The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. A cooling center is a temporary air-conditioned Public space set up by local authorities to deal with the health effects of a Heat wave.

Mortality

Heat waves are the most lethal type of weather phenomenon, overall. Between 1992 and 2001, deaths from excessive heat in the United States numbered 2,190, compared with 880 deaths from floods and 150 from hurricanes. A flood is an overflow of an expanse of water that submerges land a deluge A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding ^[7] The average annual number of fatalities directly attributed to heat in the United States is about 400. ^[8] The 1995 Chicago heat wave, one of the worst in US history, led to approximately 600 heat-related deaths over a period of five days. The 1995 Chicago heat wave was a Heat wave which led to approximately 600 heat-related deaths in Chicago over a period of five days ^[9] Eric Klinenberg, has noted that in the United States, the loss of human life in hot spells in summer exceeds that caused by all other weather events combined, including lightning, rain, floods, hurricanes, and tornadoes. The United States of America —commonly referred to as the Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to A flood is an overflow of an expanse of water that submerges land a deluge A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding A tornado is a violent rotating column of air which is in contact with both the surface of the earth and a Cumulonimbus cloud or in rare cases the base of a Cumulus ^[10][11] Despite the dangers, Scott Sheridan, professor of geography at Kent State University, found that less than half of people 65 and older abide by heat-emergency recommendations like drinking lots of water. In his study of heat-wave behavior, focusing particularly on seniors in Philadelphia, Phoenix, Toronto, and Dayton, Ohio, he found that people over 65 "don't consider themselves seniors. " "Heat doesn't bother me much, but I worry about my neighbors," said one of his older respondents. ^[12]

Underreporting and "Harvesting" effect

The number of heat fatalities is likely highly underreported due to lack of reports and misreports. ^[8] Part of the mortality observed during a heat wave, however, can be attributed to a so-called "harvesting effect", a term for a short-term forward mortality displacement. Mortality displacement denotes a (forward temporal shift in the rate of mortality in a given population usually attributable to environmental phenomena such as Heat waves or It has been observed that for some heat waves, there is a compensatory decrease in overall mortality during the subsequent weeks after a heat wave. Such compensatory reduction in mortality suggests that heat affects especially those so ill that they "would have died in the short term anyway". ^[13]

Psychological and sociological effects

In addition to physical stress, excessive heat causes psychological stress, to a degree which affects employee performance, and is also associated with an increase in violent crime. ^[14]

Power outage

Heat waves often lead to electricity spikes due to increased air conditioning use, which can create power outages, exacerbating the problem. The term air conditioning refers to the cooling and dehumidification of indoor air for Thermal comfort. A power outage (also known as power cut, power failure, power loss, or blackout) is the loss of the Electricity supply to an During the 2006 North American heat wave, thousands of homes and businesses went without power, especially in California. Mortality Reported deaths reached 22 in ten states by July 21, the end of the first stage of this heat wave A home is a place of Residence or Refuge. It is usually a place where an individual or a family can rest in and be able to store Personal property. A business (also called firm or an enterprise) is a legally recognized organizational entity designed to provide goods and/or services to California ( is a US state on the West Coast of the United States, along the Pacific Ocean. In Los Angeles, electrical transformers failed, leaving thousands without power for as long as five days. Los Angeles (lɑˈsændʒələs los ˈaŋxeles in Spanish) is the largest City in the state of California and the American West A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors ^[15]

Wildfires

If a heat wave occurs during a drought, which dries out vegetation, it can contribute to wildfires. A drought is an extended period of months or years when a region notes a deficiency in its water supply A wildfire, also known as a wildland fire, forest fire, brush fire, vegetation fire, grass fire, Peat fire, During the disastrous heat wave that struck Europe in 2003, fires raged through Portugal, destroying over 3010 km² (740,000 acres) of forest and 440 km² (108,000 acres) of agricultural land and causing an estimated €1 billion worth of damage. Country-by-country France In France, 14802 people&mdashmostly elderly&mdashdied from heat according to the country's largest funeral service Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula. A forest is an area with a high density of Trees There are many definitions of a forest based on various criteria Please update other articles as well to avoid contradiction within Wikipedia e ^[16] High end farmlands have irrigation systems to back up crops with. In Geography, arable land (from Latin arare, to Plough) is an agricultural term meaning land that can be used for

History

The European heat wave of 2003 killed around 35,000 people. Country-by-country France In France, 14802 people&mdashmostly elderly&mdashdied from heat according to the country's largest funeral service Much of the heat was concentrated in France, where nearly 15,000 people died.

In early 2006, Adelaide, South Australia was hit by a dry heat wave with temperatures reaching 40+ °C for five days in a row, while Port Augusta experienced temperatures hovering around about mid 40s °C with one day recorded at approx 48 °C. Adelaide is the capital and most populous city of the Australian state of South Australia, and is the fifth largest city in Australia with a South Australia is a state of Australia in the southern central part of the country Port Augusta (post code 5700 ( is the fifth most populous City in South Australia after Adelaide, Mount Gambier, Whyalla and Also in Sydney it reached 44. Sydney (ˈsɪdniː is the most populous city in Australia, with a Metropolitan area population of approximately 4 2 °C on the first day of 2006^[17].

In July 2006, the United States experienced a massive heat wave, and almost all parts of the country had recorded temperatures above the average temperature for that time of year. Mortality Reported deaths reached 22 in ten states by July 21, the end of the first stage of this heat wave Temperatures in some parts of South Dakota exceeded 115 °F (46 °C), causing many problems for the residents. Also, California experienced temperatures that were extraordinarily high, with records ranging from 100 to 130 °F (38 to 54 °C). On July 22, the County of Los Angeles recorded its highest temperature ever at 119 °F (48. Los Angeles County is a county in California and is by far the most populous county in the United States. 33 °C). ^[18]

The European heat wave of 2006 was the second massive heat wave to hit the continent in 4 years, with temperatures rising to 40 °C (104 °F) in Paris and even Ireland, which has a moderate maritime climate, reporting temperatures of over 32C (90 °F). Country-by-country Belgium Belgium experienced two heat waves in July 2006 Paris (ˈpærɨs in English; in French) is the Capital of France and the country's largest city Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world Temperatures of 35 °C (95 °F) were reached in the Benelux and Germany, while the United Kingdom recorded 37C. The Benelux is an economic union in Western Europe that includes three neighboring monarchies, '''Be'''lgium, the '''Ne'''therlands, and Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Many heat records were broken (including the hottest ever July temperature in the UK) and many people who experienced the heat waves of 1976 and 2003 drew comparisons with them. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located

In January 2008, Alice Springs in Australia's Northern Territory recorded ten consecutive days of temperatures above 40°C with the average temperature for that month being 39. Alice Springs is the second largest town in the Northern Territory of Australia. The Northern Territory is a federal territory of Australia, occupying much of the center of the mainland continent as well as the central northern regions 8°C.

In March 2008, Adelaide, South Australia experienced maximum temperatures of above 35°C for fifteen consecutive days, seven days more than the previous longest stretch of 35°C days. South Australia is a state of Australia in the southern central part of the country The March 2008 heat wave also included eleven consecutive days above 38°C^[19]. The heat wave was especially notable because it occurred in March, an autumn month, in which Adelaide averages only 2. 3 days above 35°C^[20].

The record for the longest heatwave in the world is generally accepted to have been set at Marble Bar in Australia, where from October 31, 1923 to April 07, 1924 the temperature broke the 37. Marble Bar is a town and rock formation in the Pilbara region of north-western Western Australia. 8°C/100°F benchmark, setting the heat wave record at a scorching 160 days.

On May 13, 2008 to May 19, 2008, the bay area experienced a heat wave with a maximum temperature of 105°F.

Another heat wave is expected to develop and penetrate most of the eastern seaboard of the United States on June 7, 2008 and last through June 11, 2008. Temperatures are expected to climb to 90°F (32°C) and above in cities as far north as Montreal. Montreal, or Montréal in French ( pronounced in French, in English) is the largest city in the Canadian province of Quebec

See also

• List of heat waves
• 2008 Southeastern/MidAtlantic US Heat Wave

Notes

• Klinenberg, Eric (2002). Heat Wave: A Social Autopsy of Disaster in Chicago. Chicago: University of Chicago Press. The University of Chicago Press is the largest University press in the United States ISBN 0226443213.  

External links

• FEMA: Extreme Heat
• Hot Weather Tips
• Marble Bar heatwave, 1923-1924
• WeatherBug Weather Wrap
• Social & Economic Costs of Temperature Extremes from "NOAA Socioeconomics" website initiative

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