The outside temperature was about and skin temperature is roughly , so the temperature difference was about . When dry, the down jacket pictured is roughly thick, which . The thermal conductivity of d...The outside temperature was about and skin temperature is roughly , so the temperature difference was about . When dry, the down jacket pictured is roughly thick, which . The thermal conductivity of dry down is roughly . Using the methods in Chapter 17 we estimate the surface area of the upper body to be . Entering these values into the equation we find:
