  Since the strong clustering of luminous matter in the observable universe is
a consequence of an initial non-uniformity of the baryon-photon fluid in the
last scattering surface, an investigation of clustering of the isotherms in the
cosmic microwave background has been performed. The isotherms clustering has
been related to the baryon-photon fluid dynamics and the Taylor-microscale
Reynolds number of this motion is estimated to be $10^2$. 3-year WMAP cosmic
microwave background map has been used in this investigation.
