A Wet-Bulb Globe Temperature (WBGT) calculator is used to approximate the outdoor bulb globe temperature (WBGT) from regular climatological inputs. It estimates the solar radiance of a clear sky by using the Kasten Czeplak algorithm.
Similarly, it uses Liljegren et al.’s (2008) process of heat and mass transfer to estimate wet-bulb globe temperature.
Wet-Bulb Globe Temperature (WBGT) is the measure of the “heat stress” in direct sunlight. It considers humidity, temperature, cloud cover (solar radiation), sun angle, and wind speed.
How To Use The Calculator
The WBGT calculator works out the WBGT directory on the grounds of three temperature components:
- DB- Dry-Bulb Temperature
- WB- Wet-Bulb Temperature
- GT- Globe Thermometer Temperature.
The calculator then gives the results in degrees Fahrenheit, which can further convert to the preferred units through a pull-down menu.
The device used to measure WBGT has three temperature elements. These include:
- Black Globe Thermometer (Tg) – Estimates wind and radiation’s joint impacts.
- Natural Wet-Bulb Thermometer (Tnwb) – is a thermometer whose bulb is covered with a wet cotton wick, dampened with distilled water. Like Tg, Tnwb isn’t guarded against radiation or wind. This thermometer represents the integrated impacts of wind, humidity, and radiation.
- Shade Air Temperature (Ta) s– It represents the air (shade) temperature reported by a thermometer guarded against solar radiation.
It works under the formula:
WBGT= (0.1×DB) + (0.2×GT) + (0.7×WB), where:
- WBGT- Wet-Bulb Globe Temperature,
- GT- Globe Thermometer Temperature, and
- DB- Dry-Bulb Temperature.
When using a WBGT calculator, it’s essential to allow the device 15 minutes to adjust to the conditions at the beginning of the measurement.
WBGT conditions change quickly. As a result, it’s advisable to read the device averagely for at least 10 to 15 minutes.
Suppose there’s an alteration in weather conditions from when the first WBGT was recorded (for example, the sky gets cloudy or the breeze stops). In that case, it’s advisable to start over again.
History of Wet-Bulb Globe Temperature Devices
It was first created for the US Marine Corps Recruit Depot in Parris Island in the late 1950s. Since the humidity at Parris Island can immensely rise, and marines were subject to rigorous training under the full sun in full military gear, there was a high risk of heat injuries. This device came in handy to monitor the sun’s heat stress and come up with healthy training habits.
It was later used by researchers across the globe to easily measure heat stress. Afterward, its uses have widened and are now commonly used by individuals and organizations worldwide. Some of the places it’s widely used include:
- OSHA, military agencies, and many states use WBGT as a guide to controlling workload under direct sunlight
- Experts advocate its use in sports demanding continuous exertion (like a marathon).
- After an ISO 7243 recommendation, the device is widely used in occupational Health and Safety for working in high-temperature environments.
With numerous advantages and the ability to show heat stress, a WBGT device is an essential tool for everyone working in direct sunlight. If the WBGT record is high, it’s vital to take many fluids to help hydrate the body.