  A semi-classical model is developed to describe pure SU(2) Yang-Mills
gluodynamics at finite temperature as a dilute, non-interacting gas of
Kraan-van Baal-Lee-Lu calorons including the case of non-trivial holonomy.
Temperature dependent parameters of the model (asymptotic caloron holonomy,
caloron density and caloron size distribution) are discussed from the point of
view of lattice observations and of in-medium modifications of the one-loop
caloron amplitude. Space-like string tensions running into plateaux at
distances R \approx 0.8 - 1.3 fm are obtained and compared to lattice results
in order to find more precisely the average caloron size. Then, the
quark-antiquark free energy as predicted by the model is considered. In the
confined phase a linear rise with the separation can be observed up to R
\approx 4 fm, whereas it runs into plateaux above T_c. Screening effects in the
adjoint potentials are observed together with an approximate Casimir scaling of
the caloron contribution to the fundamental and adjoint forces. In Abelian
projection, space-like percolation of monopoles is found in the confined phase
only. Thus, taking the non-trivial holonomy into account, confinement
properties of pure SU(2) Yang-Mills gluodynamics can be described by a
semi-classical approach up to distances one order of magnitude larger than the
caloron size.
