Bio-environmental prepares for summer 110411-F-BQ904-001

The wet-bulb globe temperature (WBGT) is a type of

apparent temperature Apparent temperature, also known as feels like, is the temperature equivalent perceived by humans, caused by the combined effects of air temperature, relative humidity and wind speed. The measure is most commonly applied to the perceived outd ...

used to estimate the effect of temperature,

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

speed (

wind chill Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...

), and visible and

infrared radiation Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

(usually

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when ...

) on

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...

s. It is used by industrial hygienists,

athlete An athlete (also sportsman or sportswoman) is a person who competes in one or more sports that involve physical strength, speed, or endurance. Athletes may be professionals or amateurs. Most professional athletes have particularly well-de ...

s, sporting events and the

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

to determine appropriate exposure levels to high temperatures. It is derived from the following formula: :

\mathrm = 0.7T_\mathrm + 0.2T_\mathrm + 0.1T_\mathrm

where * ''T''_w = Natural wet-bulb temperature (combined with dry-bulb temperature indicates humidity) * ''T''_g = Globe thermometer temperature (measured with a globe thermometer, also known as a black globe thermometer) * ''T''_d =

Dry-bulb temperature The dry-bulb temperature (DBT) is the temperature of air measured by a thermometer freely exposed to the air, but shielded from radiation and moisture. DBT is the temperature that is usually thought of as air temperature, and it is the true the ...

(actual air temperature) * Temperatures may be in either

Celsius The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The d ...

Fahrenheit The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined hi ...

Indoors, or when

solar radiation Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ...

is negligible, the following formula is often used: :

\mathrm = 0.7T_\mathrm + 0.3T_\mathrm

Uses

The

American Conference of Governmental Industrial Hygienists The American Conference of Governmental Industrial Hygienists (ACGIH) is a professional association of industrial hygienists and practitioners of related professions, with headquarters in Cincinnati, Ohio. One of its goals is to advance worker pr ...

publishes threshold limit values (TLVs) that have been adopted by many governments for use in the workplace. The process for determining the WBGT is also described in ISO 7243, Hot Environments - Estimation of the Heat Stress on Working Man, Based on the WBGT Index. The

American College of Sports Medicine The American College of Sports Medicine (ACSM), headquartered in Indianapolis, Indiana, is a sports medicine and exercise science membership organization. Founded in 1954, ACSM holds conferences, publishes books and journals, and offers certif ...

bases its guidelines on the intensity of sport practices based on WBGT. In hot areas, some US military installations display a flag to indicate the heat category based on the WBGT. The military publishes guidelines for water intake and physical activity level for acclimated and unacclimated individuals in different uniforms based on the heat category. The

University of Georgia , mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things." , establ ...

adapted these categories for use in

college sports College athletics encompasses non- professional, collegiate and university-level competitive sports and games. World University Games The first World University Games were held in 1923. There were originally called the ''Union Nationale de ...

as a guideline for how strenuous practices can be. :

Related temperature comfort measures

The

heat index The heat index (HI) is an index that combines air temperature and relative humidity, in shaded areas, to posit a human-perceived equivalent temperature, as how hot it would feel if the humidity were some other value in the shade. The result is al ...

used by the U.S.

National Weather Service 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 ...

and the

humidex The humidex (short for humidity index) is an index number used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The term ''humidex'' was coined in 1965. The humi ...

used by the

Meteorological Service of Canada The Meteorological Service of Canada (MSC; french: Service météorologique du Canada – SMC) is a division of Environment and Climate Change Canada, which primarily provides public meteorological information and weather forecasts and warnings o ...

, along with the

used in both countries, are also measures of perceived heat or cold, but they do not account for the effects of radiation. The "RealFeel" temperature is a measure offered by

AccuWeather AccuWeather Inc. is an American media company that provides commercial weather forecasting services worldwide. AccuWeather was founded in 1962 by Joel N. Myers, then a Pennsylvania State University graduate student working on a master's degree ...

, a commercial

weather forecast Weather forecasting is the application of science and technology to predict the conditions of the atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th cent ...

ing company, to purportedly combine temperature and humidity plus radiation (presumably by

approximation An approximation is anything that is intentionally similar but not exactly equal to something else. Etymology and usage The word ''approximation'' is derived from Latin ''approximatus'', from ''proximus'' meaning ''very near'' and the prefix ' ...

, since American

weather observation Weather reconnaissance is the acquisition of weather data used for research and planning. Typically the term reconnaissance refers to observing weather from the air, as opposed to the ground. Methods Aircraft Helicopters are not built to w ...

systems do not measure solar radiation directly); the RealFeel formula is a proprietary

trade secret Trade secrets are a type of intellectual property that includes formulas, practices, processes, designs, instruments, patterns, or compilations of information that have inherent economic value because they are not generally known or readily ...

References

External links

Thermal Comfort observations
from the Australian

Bureau of Meteorology The Bureau of Meteorology (BOM or BoM) is an executive agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together ...

Extreme Hot or Cold Temperature Conditions
from the

Canadian Centre for Occupational Health and Safety The Canadian Centre for Occupational Health and Safety (CCOHS) is an independent departmental corporation under Schedule II of the Financial Administration Act and is accountable to Parliament through the Minister of Labour. CCOHS functions as the ...

OSHA Technical Manual: Heat Stress
from the U.S.

Occupational Safety and Health Administration The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agen ...

Knowledge Portal WBGT
{{Meteorological variables Occupational safety and health Atmospheric thermodynamics Temperature Meteorological indices

Uses

Related temperature comfort measures

See also

References

Further reading

External links