Looking Glass Falls

Heat Index Climatology

The effects of excessive heat on the human body can be devastating. According to the National Weather Service, the 40-year period from 1936 through 1975 took the lives of nearly 20,000 as a result of the effects of heat and solar radiation. However as this number focuses on casualties that are a direct result of heat, it does not incorporate those that are simply advanced by its effects.

Heat index was devised as a way to determine how warm the outside temperature feels when relative humidity is factored in. Using the form below for various long-term measuring stations, you can retrieve or graph the number of heat index values that fall within certain thresholds. Note that heat index is calculated using the equation given in Second Edition Meteorology for Scientists and Engineers by Roland Stull:

Heat Index Table Heat Index = 16.923 + ((1.85212 x 10-1) x T)
                                  + (5.37941 x RH)
                                  - ((1.00254 x 10-1) x T x RH)
                                  + ((9.41695 x 10-3) x T2)
                                  + ((7.28898 x 10-3) x RH2)
                                  + ((3.45372 x 10-4) x T2 x RH)
                                  - ((8.14971 x 10-4) x T x RH2)
                                  + ((1.02102 x 10-5) x T2 x RH2)
                                  - ((3.8646 x 10-5) x T3)
                                  + ((2.91583 x 10-5) x RH3)
                                  + ((1.42721 x 10-6) x T3 x RH)
                                  + ((1.97483 x 10-7) x T x RH3)
                                  - ((2.18429 x 10-8) x T3 x RH2)
                                  + ((8.43296 x 10-10) x T2 x RH3)
                                  - ((4.81975 x 10-11) x T3 x RH3)

where T is the dry bulb temperature (°F) and RH is relative humidity (%)




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