Author(s): Stephanie Grothe; Kenneth Hughes; Pat Langhorne
Linked Author(s): Patricia Langhorne
Keywords: No Keywords
Abstract: Seven experiments on ice grown in water of differing salinities (0 < S < 3.0 ppt) are undertaken to determine the most important drivers of ice crystal orientation. In six experiments, the water is not stirred, the ice cover is unseeded, and ice grows at approximately 1.6 mm hr-1. Under these conditions we find that crystal c-axis inclinations are predominantly vertical at water salinities less than 1.2 ppt and predominantly horizontal at salinities greater than 2.0 ppt. We also observe a transition from a planar to cellular interface between these salinities. Together, these observations suggest that the change in dominant crystal orientation is explained by constitutional supercooling and its influence on the morphological instability of the ice–water interface. However, in the ice that forms initially at the ice–air interface, the crystal orientation appears to be controlled by the temperature profile in the water close to the interface. The experimental evidence suggests that c-axis vertical orientations are more likely in the initial skim if there is a hydrodynamically stable layer at the interface.
Year: 2014