I hope everyone there is taking care
Deadly ‘Wet-Bulb’ Temperatures Are Smothering the Eastern U.S.
An oppressive heat dome has gripped the eastern U.S. this week, prompting the National Weather Service (NWS) to issue heat warnings for nearly 170 million Americans. To make matters worse, severe humidity is making high temperatures feel even hotter.
Taking the wet-bulb temperature into account with air temperature, wind speed, cloud cover, and the angle of the Sun gives meteorologists the wet-bulb globe temperature (WBGT), a comprehensive measure of heat stress in direct sunlight. On Tuesday, July 29, the NWS reported WBGT values in the high 80s to low 90s Fahrenheit (upper 20s to mid-30s Celsius) across much of the eastern U.S., particularly in the Southeast and Midwest.
WBGT values above 90 degrees Fahrenheit (32 degrees Celsius) are extreme and can induce heat stress in just 15 minutes when working or exercising in direct sunlight, according to the NWS. Weather officials expect these conditions to persist through Wednesday, July 30, before the heat dome dissipates later in the week.
Experts have long believed that a wet-bulb temperature of 35 degrees Celsius (equal to 95 degrees Fahrenheit at 100% humidity or 115 degrees Fahrenheit at 50% humidity) was the threshold at which the human body can no longer cool itself. In recent years, however, researchers have found evidence to suggest that this threshold is actually much lower.
“Based on our research, a wet bulb temperature of around 87 degrees Fahrenheit [30.6 degrees Celsius] at 100% humidity is the critical threshold above which humans cannot maintain a stable core temperature if they were exposed to those conditions for hours at a time,” Kat Fisher, a PhD candidate in the human thermoregulatory lab at Penn State University, told Gizmodo in an email.
This National Weather Service (NWS) map shows the projected wet-bulb globe temperatures (WBGT) for Wednesday, July 30 at 3:00 p.m. ET. Areas in red can expect to see "high" WBGT conditions, and areas in grey can expect "extreme" conditions