The THW index offers more information about human comfort levels outdoors than temperature alone.
High humidity can make the outdoors feel warmer and exacerbate allergic reactions. At the same time, high winds can make a warm day feel cooler than the reported temperature. By calculating the temperature-humidity-wind (THW) index, you will gain offer a more accurate understanding of outdoor weather conditions and your expected comfort level.
Instructions
Instructions
1. Obtain the outdoor temperature in degrees Fahrenheit using the psychrometer. The psychrometer measures a dry bulb and a wet bulb temperature. The outdoor temperature is the dry bulb temperature.
2. Calculate the outdoor relative humidity using the psychrometer. The relative humidity is the difference between the dry bulb and wet bulb values, expressed as a rounded percentage.
3. Calculate the heat index using the formula HI = -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783x10-3T2 - 5.481717x10-2R2 + 1.22874x10-3T2R + 8.5282x10-4TR2 - 1.99x10-6T2R2. The variable T is the outdoor temperature and the variable R is the relative humidity.
4. Obtain the outdoor wind speed in miles per hour using the anenometer. To improve accuracy, hold the anenometer a few feet above the ground.
5. Calculate the THW Index using the formula THW = HI - (1.072 * W). The variable HI is the heat index, and the variable W is the wind speed.
Tags: outdoor temperature, relative humidity, bulb bulb, bulb temperature, Calculate Index, heat index, Obtain outdoor