One way of increasing heat transfer from the head on a hot summer day is to wet

Question:

One way of increasing heat transfer from the head on a hot summer day is to wet it. This is especially effective in windy weather, as you may have noticed. Approximating the head as a 30-cm-diameter sphere at 30°C with an emissivity of 0.95, determine the total rate of heat loss from the head at ambient air conditions of 1 atm, 25°C, 30 percent relative humidity, and 25 km/h winds if the head is

(a) Dry

(b) Wet. Take the surrounding temperature to be 25°C. Evaporation Wet 30C 1 atm 25C 30% RH 25 km/h