  This is the extended version of the preprint \ct{Loop}, based on the lectures
given in Cargese Summer School and Chernogolovka Summer School in 93. The
incompressible fluid dynamics is reformulated as dynamics of closed loops $C$
in coordinate space. We derive explicit functional equation for the pdf of the
circulation $P_C(\Gamma)$ which allows the scaling solutions in inertial range
of spatial scales. The pdf decays as exponential of some power of $
\Gamma^3/A^2 $ where $A$ is the minimal area inside the loop.
