The role of solar heat absorbed in ice of medium thickness is investigated with a one-dimensional nonstationary thermodynamic model of the snow-ice cover. Different ways of considering short-wave solar radiation and their effect on the accuracy of calculations of snow and ice thickness for the actual weather conditions observed at the drifting station North Pole-13 and in Kandalaksha Bay of the White Sea are demonstrated. The absorption of short-wave solar radiation by ice-cover thickness is considered through the reconstruction of nonlinear temperature profile in ice. The results obtained allow us to conclude that the model suggested reproduces adequately the seasonal variations in the ice-cover thickness and the characteristics of its vertical thermal structure.