We analyze the heat capacity C P for low and high-density amorphous ice below the transition temperature (T C ≈ 140 K) using a power-law formula. The renormalized critical exponent α R is extracted from the observed C P data, which describes similar critical behavior for both low and high-density amorphous ice below T C . Our analysis can also describe a glass transition in the low-density amorphous ice which is made from the high-density amorphous ice at 124 K, as observed experimentally.