ABSTRACT
The temperature distribution in a glacier is important because the rate of deformation increases rapidly as the ice becomes warmer (Section 2.2). Further, where the basal temperature reaches the pressure-melting temperature, basal melting may lead to the development of an interstitial layer of meltwater and the onset of basal sliding, resulting in ice velocities that can be orders of magnitude greater than those associated with internal deformation (c.f. Chapter 7). The starting point when considering the heat budget of a glacier is the first law of thermodynamics, which states that, in a closed system, no energy can be created or destroyed. Using this law, and some elementary thermodynamics, the thermodynamic or temperature equation can be derived. The following discussion is largely based on the extensive treatment of this topic given in Brown (1991). Readers not interested in the nuts and bolts of thermodynamics can skip this section and take equation (6.17) for granted.
