Question 2: Frozen puddles As the weather starts to cool off for fall, you might soon notice frozen puddles on the sidewalk, especially in the early morning. Consider the overnight conditions detailed in the diagram to the right where the clear sky has an effective temperature of -20C, the temperature beneath the sidewalk is constant at 5C, and the air temperature is unknown. T-20C Tam = ?? h = 10 100 mm Sidewalk k-0.81-0.9 Constant temperature on underside of concrete, T-SC a) Draw a fully labeled thermal resistance diagram that describes the relevant heat transfer processes from the surface of the sidewalk. Label all resistances, temperatures, and indicate any relevant heat transfers. b) For the conditions shown in the diagram, what is the maximum air temperature at which a puddle on the sidewalk could freeze?