LST = S8_BT_in_M + (1.084 * (S8_BT_in_M - S9_BT_in_M)) + (0.2771 * ((S8_BT_in_M - S9_BT_in_M) ^ 2)) + (-0.268) + ((45.1 + (-0.73 * water_vapour_S)) * (1- emis_effect_S)) + (((-125 + (16.7 *  water_vapour_S))) * (emis_diff_S))