Physics of ice Glaciers and ice sheets consist

Physics of ice • Glaciers and ice sheets consist of ice – Thus the physical qualities of ice (and water) define the behaviour of these ice masses – The viscosity of ice is many orders of magnitude smaller than that of rocks – Ice and water coexist in glaciers, thus influence their dynamics

Water on Earth • 90%? in the interior of the Earth • 10% at or above the Earth’s surface, of which – 97. 390% in the oceans (salt water, sea ice) – 0. 019% in lakes and rivers (fresh water) – 0. 580% ground water – 2. 010% ice in ice sheets and glaciers – 0. 001% liquid, solis or gaseous in the atmosphere

Water and Ice • Water (ice) is one of the most anomalous substances: The most important qualities: – – Ice floats on water Melting point decreases with increasing pressure Maximum density at 4 o. C Very high melting and freezing point compared to related compositions of related elements These qualities make life as we know possible!?

• High melting and boiling point: – Hydrogen bridges between the Oxigen atom of a water molecule and one of the Hydrogen atoms of the next

Tetrahedral arrangement of the water molecules O H H 104. 52° 109. 47°for regular tetrahedrons Coordination number 4: each water molecule in an ice cristall has 4 neighbouring water molecules

• Liquid phase – irregular – mobile – coordination number > 4 • Eiskristall – regular (O-atoms) – immobile – Coordination number 4 Water is denser than hexagonal ice

Water and ice: density vs. temperature

Annalen der Physik und Chemie, 1892, Vol. 43, S. 91 -97 heute nachgewiesen durch Streuexperimente mit den von Röntgen 1895 entdeckten „Röntgenstrahlen“. Er erhielt dafür den 1. Nobelpreis für Physik im Jahre 1901

Melting point of pure ice: pressure dependence Temperature relative to pressure melting point

Properties of ice