  We study the finite-temperature behavior of the A^2 condensate in the Landau
gauge of SU(2) Yang--Mills theory on the lattice in a wide range of
temperatures. The asymmetry between the electric (temporal) and magnetic
(spatial) components of this unconventional dimension-2 condensate is a
convenient ultraviolet-finite quantity which possesses, as we demonstrate,
unexpected properties. The low-temperature behavior of the condensate asymmetry
suggests that the mass of the lowest thermal excitation in the condensate is
unexpectedly low, about 200 MeV, which is much smaller than the glueball mass.
The asymmetry is peaking at the phase transition, becoming a monotonically
decreasing function in the deconfinement phase. A symmetric point is reached in
the deconfinement phase at a temperature approximately equal twice the critical
temperature. The behavior of the electric-magnetic asymmetry of the condensate
separates the phase diagram of Yang-Mills theory into three regions. We suggest
that these regions are associated with the condensed, liquid and gaseous states
of the confining gluonic objects, the Abelian monopoles.
