Letter: Heat-stress scale includes the impact of sun’s angle

Heat-stress scale includes
the impact of sun’s angle

Here in California a 90°F day is annoying but tolerable. But heat is only part of the issue in determining the effect of warming on living organisms; the other primary determinants are humidity and solar radiation.

There is a scale, used by the military and others, to measure heat stress in high humidity and direct sunlight. It incorporates humidity, wind speed (wind chill) and sun angle to measure heat stress. It is called the WetBulb Globe Temperature.

To give a quick example, on a given day, say the temperature in Paris is 87°F, and in Calcutta it’s only 84°F. But because of relative humidity in Paris is 38% and 86% in Calcutta, the WBGT in Calcutta is a “very high risk” 92°F, while in Paris it’s a “moderate” 82°F.

Because WBGT tells us what we need to know about functioning on a given day and allows us to appreciate the news of record warming elsewhere, it should become part of weather reports.

James Wolpman
Walnut Creek

 

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Source: mercurynews
Letter: Heat-stress scale includes the impact of sun’s angle