Plant leaves possess small channels that connect the interior moist region of the leaf to the environment. The channels, called stomata, pose the primary resistance to moisture transport through the entire plant, and the diameter of an individual stoma is sensitive to the level of CO₂ in the atmosphere. Consider a leaf of corn (maize) whose top surface is exposed to solar irradiation of G_S = 600 W/m2 and an effective sky temperature of T_sky = 0°C. The bottom side of the leaf is irradiated from the ground which is at a temperature of T_g = 20°C. Both the top and bottom of the leaf are subjected to convective conditions characterized by h = 35 W/m² · K, T_∞ = 25°C and also experience evaporation through the stomata. Assuming the evaporative flux of water vapor is 50 X 10^–6 kg/m² · s under rural atmospheric CO² concentrations and is reduced to 5 X 10^–6 kg/m² · s when ambient CO² concentrations are doubled near an urban area, calculate the leaf temperature in the rural and urban locations. The heat of vaporization of water is h_fg = 2400 kJ/kg and assume α = ε = 0.97 for radiation exchange with the sky and the ground, andα_S = 0.76 for solar irradiation.