surface spherical harmonic

Any linear combination of real spherical harmonics A_l P_l(cos θ) + sum_(m = 1)^l[A_l^m cos(m ϕ) + B_l^m sin(m ϕ)] P_l^m(cos θ) for l fixed whose sum is not premultiplied by a factor r^l.

solid harmonic | spherical harmonic