The dependences of the temperature T and electric field strength E on the current I and radius R for a axisymmetric stationary equilibrium arc discharge in air, argon, carbon dioxide and hydrogen under atmospheric pressure are determined from the solution to the Elenbaas–Heller equation. The results of computations are given on diagrams in the plane lgI–R in the form of lines of constant values. The diagrams make it possible to rapidly estimate parameters of the arc discharge for the given values of I and R.