HEAT INDEX CHART

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THE FOLLOWING HEAT INDEX CHART IS PROVIDED FOR YOUR CONVENIENCE. THE FIRST COLUMN ON THE LEFT IS THE AIR TEMPERATURE AND THE TOP LINE IS THE RELATIVE HUMIDITY.

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RELATIVE HUMIDITY

TºF	35%	40%	45%	50%	55%	60%	65%	70%	75%	80%	85%	90%	95%
115	143	151
110	130	137	143	150
105	118	123	129	135	142	149
100	107	110	115	120	126	132	138	144
95	98	101	104	107	110	114	119	124	130	136
90	91	93	95	98	100	102	106	109	113	117	122
85	85	86	87	88	89	90	91	93	95	97	99	102	105
80	79	79	80	81	81	82	83	85	86	86	87	88	89
75	73	74	74	75	75	76	76	77	77	78	78	79	79
70	67	68	68	69	69	70	70	70	70	71	71	71	71

FOR THOSE OF YOU DIE HARD MATH FANS, HERE IS THE EQUATION AND A FEW OF THE PARAMETERS INVOLVED IN THE CALCULATION.  SOME PARAMETERS CONSIDERED:  VAPOR PRESSURE, EFFECTIVE WIND SPEED, DIMENSIONS OF A HUMAN, INTERNAL BODY TEMPERATURE OF A HUMAN, AND THE SWEATING RATE OF A HUMAN.

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WITH THESE AND SEVERAL OTHER PARAMETERS CONSIDERED THE FOLLOWING EQUATION IS DERIVED:

HI= -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783X10**-3T**2 - 5.481717X10**-2R**2 + 1.22874X10**-3T**2R + 8.5282X10**-4TR**2 - 1.99X10**-6T**2R**2

WHERE
T=AMBIENT DRY BULB TEMPERATURE
R=RELATIVE HUMIDITY
**=RAISED TO THE POWER OF...
(EXAMPLE 6.83783X10**-3T**2 IS READ 6.8378 TIMES TEN RAISED TO THE POWER OF -3 TIMES T SQUARED).

THIS EQUATION WAS DERIVED FROM A STUDY CONDUCTED AND PUBLISHED BY R.G. STEADMAN IN 1979.

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