Before revision: (Pa K−1) Rn = Net irradiance (MJ m−2 day−1), the external source of energy flux G = Ground heat flux (MJ m−2 day−1), usually equivalent to zero on a day T = Air temperature at 2m (K) u_2 = Wind speed at 2m height (m/s) δe = vapor pressure deficit (kPa) γ = Psychrometric constant (γ ≈ 66 Pa K−1) N.B.
After revision: (Pa K−1) Rn = Net irradiance (MJ m−2 day−1), the external source of energy flux G = Ground heat flux (MJ m−2 day−1), usually equivalent to zero on a day T = Air temperature at 2m (K) u2 = Wind speed at 2m height (m/s) δe = vapor pressure deficit (kPa) γ = Psychrometric constant (γ ≈ 66 Pa K−1) N.B.