For the inhabitants of humid climates, the combination of high temperatures and high humidity can be deadly. This was in evidence when several marathon runners were overcome by heat exhaustion during a Columbus Day marathon in Chicago, Illinois. When humidity rises in the presence of warm temperatures, the body’s ability to shed heat is diminished. The relative discomfort due to combined heat and high humidity is the apparent temperature. Sunstroke is possible when the apparent temperature reaches 90^oF and is likely at 105^oF, Heatstroke is possible over the same range and imminent when exceeding 130^oF

Heat-related illnesses will only increase as our atmosphere continues to warm. Climate modelers predict that not only are temperatures to rise but humidity as well from increased evaporation. According to a recent study, humidity has increased over most of the globe. However, while the eastern United States is more humid, the western U.S., South Africa and parts of Australia are experiencing drought conditions.

Read more about:

• Steamier Earth Likely, Due to Global Warming (National Geographic)

Or watch (for a chuckle) When Good Science Goes Bad - Humidity

TPE Links - Evaporation; Humidity

Graphic courtesy NWS NOAA