Air at -5°C flows over the wall of a building with a velocity of 10 m/s. The length of the wall in the direction of air flow is 6 m. The wall is also subjected to a solar insulation of 40 W/m2, and its emissivity is 0.8. Assume an average and constant temperature over the surface of the wall and that all the solar insulation is absorbed by the wall. (a) Determine whether the air flow over the wall is laminar, turbulent, or mixed; (b) Calculate the wall surface temperature assuming that the irradiation from the sky is zero; (c) Repeat part (b) by accounting for the irradiation from sky whose temperature is -35 °C.