  It has recently been found that dynamics of pure glue QCD supports the low
energy band of Dirac modes with local chiral properties qualitatively different
from that of a bulk: while bulk modes suppress chirality relative to
statistical independence between left and right, the band modes enhance it. The
width of such chirally polarized zone - chiral polarization scale Lambda_ch -
has been shown to be finite in the continuum limit at fixed physical volume.
Here we present evidence that Lambda_ch remains non-zero also in the infinite
volume, and is therefore a dynamical scale in the theory. Our experiments in
N_f=2+1 QCD support the proposition that the same holds in the massless limit,
connecting Lambda_ch to spontaneous chiral symmetry breaking. In addition, our
results suggest that thermal agitation in quenched QCD destroys both chiral
polarization and condensation of Dirac modes at the same temperature T_ch >
T_c.
