Moist Heatwave:
Research showed that timings and locations of the moist heatwaves are controlled by the active and break periods of the southwest monsoon (SWM) season and can be predicted weeks in advance.
- Moist heatwaves are triggered by a combined impact of high temperatures and elevated humidity levels in the atmosphere.
- The best way to measure the combined effect of humidity and temperature is ‘wet bulb temperature’.
- Wet bulb temperature is the lowest temperature to which air can be cooled by the evaporation of water into the air at constant pressure.
- This is a process happening on human skin when people sweat.
- The globally accepted level for wet bulb temperature that forms the limit of human survivability is 35°C.
- When air is already humid, sweat cannot evaporate from skin, leaving the body unable to cool itself. This can lead to heat exhaustion and fatal heatstroke within hours.
- It is because high humidity impairs evaporation, limiting the human body’s ability to dissipate metabolic heat and regulate core temperature.
- In such circumstances, the physiological strain on the human body intensifies, exacerbating the risks of cardiovascular and respiratory illnesses.
- A thermoregulatory failure can lead to hyperthermia, heat exhaustion, and fatal heatstroke in extreme cases.
