چکيده

Abstract One of the factors influencing the altitude of water and ice equilibrium line is the amount of the energy received from sun which depends on the radiation angles of sun and the slope. Thus, as the surfaces slopes vary, the absorption of energy will also change. Initially, this article makes an attempt to measure the radiation angle and the energy absorbed daily by the surface of land with respect to different slopes and directions. Then, the differences between the amounts of energy absorbed by two different surfaces varying in terms of slope and direction will be estimated, considering a constant temperature. Consequently, the energy differences will be converted to altitude differences, using the statistical relations. This paves the way for the estimation of the differences in altitude of water and ice equilibrium line. Although this article has used a hypothetical altitude, the resulting finding can also be used in the context of the past ages because the altitude of water and ice equilibrium line was low at the ice age of quaternary. This study had the following findings; 1- Averaged reduction of temperature of environment is .48 per 100 meters increasing in height with reduction of temperature in Iran about 5-12  in quaternary period height of snow is downer about 1042-2500 then current circumstance. 2- The highest impact of the land surfaces directions on the altitude of ice and water equilibrium line can be seen in the skirts whose mountainous ridges expansion is west and east. 3- The north-south expansion of mountainous ridges doesn’t have any effect on the difference in altitude of ice and water equilibrium line. Key words: altitude, water and ice equilibrium, quaternary, energy, sun radiation, slope