Isotherms clustering in cosmic microwave background

Isotherms clustering in cosmic microwave background (CMB) has been studied using the 3-year WMAP data on cosmic microwave background radiation. It is shown that the isotherms clustering could be produced by the baryon–photon fluid turbulence in the last scattering surface. The Taylor-microscale Reynolds number of the turbulence is estimated directly from the CMB data as Reλ∼102Reλ∼102.