The rate factor A(T) of Glen’s law, also called the softness of the ice, is written A=A0exp(−Q/RT), with an activation energy Q. A widely used fit (Paterson and Budd) takes A0=3.61×10−13s−1Pa−3 and Q=60kJ/mol below −10∘C, and A0=1.73×103s−1Pa−3 and Q=139kJ/mol above it, closer to the melting point, where the ice softens faster with temperature.