Glosari: Índex de calor

The heat index as an index that combines air temperature and relative humidity to determine the human-perceived equivalent temperature. The resulting apparent temperature is crucial to assess possible effects of the weather for the human body. High relative humidity reduces the evaporation rate of sweat, lowering the body's self-cooling.

The heat index is calculated based on temperatures in the shade. Exposure to full sunshine can increase heat index values by up to 14 °F (8 °C).

Nivells de calor

< 80 °F (27 °C) – Cap efecte
Temperature and humidity should not have any effect.
< 91 °F (33 °C) – Precaució
Fatigue is possible with prolonged exposure and activity. Continuing activity could result in heat cramps.
< 105 °F (41 °C) – Precaució extrema
Heat cramps and heat exhaustion are possible. Continuing activity could result in heat stroke.
< 130 °F (54 °C) – Perill
Heat cramps and heat exhaustion are likely; heat stroke is probable with continued activity.
≥ 130 °F (54 °C) – Perill extrem
Heat stroke is imminent.

References

Steadman, R. G.: The Assessment of Sultriness. Part I: A Temperature-Humidity Index Based on Human Physiology and Clothing Science, Journal of Applied Meteorology, 18 (7): 861–873, 1979, doi:10.1175/1520-0450(1979)018<0861:TAOSPI>2.0.CO;2
Rothfusz, L. P.: The Heat Index 'Equation' (or, More Than You Ever Wanted to Know About Heat Index), Scientific Services Division (NWS Southern Region Headquarters), 1990, wonder.cdc.gov [pdf]
National Weather Service: Heat Index, www.nws.noaa.gov

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