Heat Index, Wet Bulb Globe Temperature... New metrics when temperatures don't cooperate.

Since temps are not close to approaching those of the 1930s, 40s, or 80s, during this 'unprecedented' heat wave, climate alarmists have shifted away from temp to new metrics.

Heat Index…

The heat index is a measure that combines air temperature and relative humidity to determine an apparent temperature — how hot it truly feels. When the body gets hot, it cools itself primarily through the process of evaporation, i.e., sweating. When the relative humidity is high, the evaporation rate is reduced, which means the body feels hotter in humid conditions than when it's dry.

The heat index is used to advise the general public about the potential dangers of heat-related illnesses, such as heat exhaustion or heat stroke, especially when the heat index value climbs above 90°F (32°C).

The concept of the heat index, or something akin to it, has been understood for many years, but the term "heat index" and its present algorithm were developed by the U.S. National Weather Service (NWS) in the 1970s. The formula used by the NWS was devised in 1978 by George Winterling and was further refined by the NWS in 1990 based on research by Robert Steadman.

As for records of the heat index, since it's a derived value based on temperature and humidity, we can theoretically go back and compute the heat index for any day in the past for which we have those two measurements. Direct measurements of temperature and humidity (from instruments like thermometers and hygrometers) have been available for more than a century in many parts of the world. However, the consistency and spatial distribution of these records vary. In the U.S., for example, few temperature and humidity records date back to the early 1900s. Thus, it’s essentially not possible to compare the modern heat index to one from the 1930s, for example.

Source: https://www.weather.gov/ama/heatindex

Wet Bulb Globe Temperature…

The Wet Bulb Globe Temperature (WBGT) is a composite temperature used to estimate the effect of temperature, humidity, wind speed (air movement), and solar radiation on humans. It's especially useful in understanding heat stress in direct sunlight, which takes into account solar radiation, not just heat and humidity like the heat index. WBGT is commonly used in industrial and sports settings to determine appropriate exposure levels to high temperatures.

The WBGT is derived from three temperature readings:

1. Wet Bulb Temperature (WB): Measured using a thermometer bulb that is kept wet, which gives a temperature reading based on the cooling effect of evaporation. It represents the combined effect of temperature and humidity.

2. Globe Temperature (GT): Measured using a thermometer placed at the center of a 6-inch hollow copper sphere painted black. It assesses the combined effects of temperature and radiant heat.

3. Dry Bulb Temperature (DB): This is just the regular air temperature, measured by a thermometer freely exposed to air but shielded from radiation and moisture.

The formula to compute WBGT varies slightly depending on whether you're inside (with no solar load) or outside:

• Inside (or in full shade): WBGT = 0.7WB + 0.3GT

• Outside (in direct sunlight): WBGT = 0.7WB + 0.2GT + 0.1DB

The concept of WBGT can be traced back to the 1950s. It was initially developed by the U.S. military as a response to a series of heat-related incidents during training exercises. The goal was to find a better metric to evaluate the potential for heat stress, especially for soldiers who might be active in various challenging environments.

Regarding records of WBGT, since it's a derived value based on a combination of temperature readings, we can theoretically compute the WBGT for any period for which we have the necessary measurements. However, dedicated WBGT measurements, especially those made with specialized equipment, are not as old as simpler temperature and humidity records. Consistent records of WBGT specifically are more recent, primarily from the latter half of the 20th century onward, and these records would primarily be focused in specific areas or contexts (like military training grounds or certain research stations) rather than broad geographic areas.

Source: https://www.weather.gov/ict/wbgt

But if anthropogenic GHG emissions are trapping IR escaping Earth and warming the surface surely we should see that in the daily maximum temperatures recorded in US cities.

Max daily temperatures for US cities and forecast for this ‘unprecedented’ heat wave event…