The CMB angular anisotropies are usually presented in terms of power per multipole. The angular the map of temperature across the sky, T ( θ θ , φ φ ) , is written as coefficients of spherical harmonics, T ( θ θ , φ φ ) = ∑ ∑ ℓ ℓ m a ℓ ℓ m Y ℓ ℓ m ( θ θ , φ φ ) where the a ℓ ℓ m term measures the strength of the angular oscillation in Y ℓ ℓ m ( θ θ , φ φ ) , and ℓ is the multipole number while m is the azimuthal number. The azimuthal variation is not significant and is removed by applying the angular correlation function, giving power spectrum term C ℓ ℓ ≡ ≡ ⟨ ⟨ | a ℓ ℓ m | 2 ⟩ ⟩ . Increasing values of ℓ correspond to higher multipole moments of CMB, meaning more rapid variation with angle.