  For systems exhibiting a second-order phase transition with a spontaneously
broken continuous O(N)-symmetry at low temperature, we give a criterion for
judging at which temperature T_K long-range directional fluctuations of the
order field destroy the order when approaching the critical temperature from
below. The temperature T_K lies always significantly below the famous Ginzburg
temperature T_G at which size fluctuations of finite range in the order field
become important.
