About RF Cafe Copyright: 1996 - 2024Webmaster:     BSEE - KB3UON RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived... All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged. My Hobby Website: AirplanesAndRockets.com

# Heat Index Chart - Relative Humidity vs. Air Temperature

As one who is severely discomforted by a combination of heat and humidity, this kind of table is of great interest. If I am going to be miserable, I want to know exactly how miserable I really am! This information is derived from NOAA Click here for a windchill chart.

 Extreme Danger - Heat stroke or sun stroke likely Danger - Sunstroke, muscle cramps and/or heat exhaustion likely Extreme Caution - Sunstroke, muscle cramps and/or heat exhaustion possible Caution - Fatigue possible

NOAA provides the following equation for calculating heat index:

HI = -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783x10-3T2

- 5.481717x10-2R2 + 1.22874x10-3T2R + 8.5282x10-4TR2 - 1.99x10-6T2R2,

where T = ambient dry bulb temperature (°F) R = relative humidity (integer percentage)

"Because this equation is obtained by multiple regression analysis, (HI) has an error of ±1.3°F"

 AirTemp(°F) Relative Humidity (%) 40 45 50 55 60 65 70 75 80 85 90 95 100 110 136 108 130 137 106 124 130 137 104 119 124 131 137 102 114 119 124 130 137 100 109 114 118 124 129 136 98 105 109 113 117 123 128 134 96 101 104 108 112 116 121 126 132 94 97 100 102 106 110 114 119 124 129 136 92 94 96 99 101 105 108 112 116 121 126 131 90 91 93 95 97 100 103 106 109 113 117 122 127 132 88 88 89 91 93 95 98 100 103 106 110 113 117 121 86 85 87 88 89 91 93 95 97 100 102 105 108 112 84 83 84 85 86 88 89 90 92 94 96 98 100 103 82 81 82 83 84 84 85 86 88 89 90 91 93 95 80 80 80 81 81 82 82 83 84 84 85 86 86 87