In atmospheric radiation, Chandrasekhars H-function appears as the solutions of problems involving scattering, introduced by the Indian American astrophysicist Subrahmanyan Chandrasekhar. The Chandrasekhars H-function  defined in the interval , satisfies the following nonlinear integral equation
where the characteristic function  is an even polynomial in  satisfying the following condition
If the equality is satisfied in the above condition, it is called conservative case, otherwise non-conservative. Albedo is given by . An alternate form which would be more useful in calculating the H function numerically by iteration was derived by Chandrasekhar as,
In conservative case, the above equation reduces to