Heat Stress WBGT

Measurement

The WBGT is measured by a simple three-temperature element device:

The natural wet-bulb temperature (Tw), which consists of a thermometer with its bulb covered with a wettened cotton wick supplied with distilled water from a reservoir. The cotton wick will always be wet, allowing continuous evaporative cooling of the thermometer's bulb, simulating the evaporation of sweat. The natural wet-bulb thermometer, like the black globe thermometer is not shielded from wind or radiation. This thermometer represents the integrated effect of humidity, wind and radiation.The black globe temperature (Tg), which usually consists of a 150 mm (6 inch) black globe with a thermometer located at the center. The black globe temperature represents the integrated effects of radiation and wind.The (shade) air temperature (Ta), which consists of a thermometer shielded from radiation - generally by being placed in a weather screen. It is the standard temperature normally quoted in weather observations and forecasts.Calculations

We have recently acquired a CASELLA H.M.S 100 WBGT Ex-MoD hand-held instrument

We've added another instrument to the automated weather station called a (Tg) black globe temperature sensor. Using our aspirated screen (Tw) wet bulb temperature and a (Ta) screen dry bulb temperature. Using this formula WBGT = (0.7 × Tw) + (0.2 × Tg) + (0.1 × Ta)

We can work out what the WBGT heat stress measurement is at our location.

The wet-bulb globe temperature (WBGT) is a type of apparent temperature used to estimate the effect of temperature, humidity, wind speed (wind chill), and visible and infrared radiation (usually sunlight) on humans.

Welcome to Weather-Above

The three elements Tw, Tg, and Ta are combined into a weighted average to produce the WBGT.

We are using this to check against our automated sensors

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Weather data is based on a Amateur Hobbyist readings

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WBGT

(0.7 × Tw)

(0.2 × Tg)

(0.1 × Ta)

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