อนุทิน 174482

ดัชนีความร้อน (Heat Index)

ทั่วไทยร้อนจัด ภาคเหนือร้อนทะลุปรอท 44 องศา กทม.ระอุ 41 องศา [แนวหน้า]
ค่าดัชนีความร้อน กทม.อยู่ในเกณฑ์อันตรายมาก (41C - 51C) …

The news headlines are worrying. They tell of impending danger with a measure that is more subjective.
Heat Index : temperature we feel; it is estimated from thermometer temperature and relative humidity with a NOAA heat index chart (https://www.noaa.gov/sites/default/files/2022-05/heatindex_chart_rh.pdf or https://www.weather.gov/ffc/hichart ) .

Why do we sweat when it is hot? It is not only the high temperature but also the humidity. It is really about the dew point when we sweat. So, we sweat because of temperature + high humidity. Why we have high humidity? … We have a convoluting system (when when interacting ‘parts’ have interacting effects or feedbacks on each other; high T –> high humid –> more dew/sweat –> high heat index –> high use of energy to coll down –> high ambient T –> high humid –>… )