Colloquium

Consider the Icicle, Stephen Morris, University of Toronto

Fri, 24 Jan 2020 2:30 PM
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Colloquium

Stephen Morris
University of Toronto

Consider the Icicle, Stephen Morris, University of Toronto

Jan 24, 2020 at 2:30pm in C9000

Synopsis

Icicles are harmless and picturesque winter phenomena, familiar to anyone who lives in Canada.  The shape of an icicle emerges from a subtle feedback between ice formation, which is controlled by the release of latent heat, and the flow of water over the evolving shape. Ideal icicles are predicted to have a universal "platonic" shape, independent of growing conditions.  In addition, many natural icicles exhibit a ripply shape, which is the result of a morphological instability.  The wavelength of the ripples is also remarkably independent of the growing conditions.  Similar shape and ripple phenomena are also observed on stalactites, although certain details of their formation differ.  We built a laboratory icicle growing machine to explore icicle physics. We learned what it takes to make a platonic icicle and the surprising origin of the ripples.