A simple radiation model from the class of one-dimensional radiation models is proposed. The model is described by ordinary differential equations for temperature of the layers. Temperature dependence is determined by the Planck's function, and this dependence is explicit. The model allows one to study the effect of variations in the concentration of minor atmospheric constituents on the evolution of temperature profile, the stability characteristics of the steady-state profile, and on the relaxation times. It is shown that variations of the concentration by a factor of 2 to 3 do not change the character of the steady state that remains a stable node, but affect the degree of stability by changing the relaxation times that increase with height. It is also shown that introduction of the albedo-temperature relation can lead to the appearance of an additional stable temperature profile with the temperature lower than that taking place nowadays.