What is ICE?

THE PHYSICS OF HOCKEY! Sliding Friction and Momentum on Ice

What is ICE?

The Importance of ICE~

Ice is abundant on the Earth's surface, in the planetary system, and in interstellar space. If all the ice presently existing on earth melted, sea level would rise to about 70 m. The melting of ice is a major concern for the survival and health of many species because this brings changes to their ecosystems and migration patterns. The emmission of "green house" gases from industrial plants have created holes in the ozone layer, causing the Earth to warm up. Hence, this "Green House Effect" is melting away the supply of ice. (Physics Encyclopedia, "Ice", 1998)

ko's vector gif

Ice is the essential ingredient of moons, planets, and comets.
Take note of the ice compositions:

1)Pluto, the farthest planet from the Sun is 80% ice
2)Jupiter's moons Ganymede and Callisto contain 40% ice
3)Saturn's Titan contains 40% ice

Finally, the mass of the ice stored in the terrestrial polar ice sheets and in alpine glaciers is closely related to the climate. (Robinson, 1965)

Below are pictures of a glacier and an iceberg:

these are from Corbis

More structures of ice.... click
to enlarge diagrams

This figure shows the nine phases of ice as a function of temperature and pressure. Normal ice exists in the region marked Ih. The ``h'' stands for hexagonal. The figure is from (Hobbs, 1970, p. 61)

Encyclopedia of Physics, 1998

Whalley and his team discovered and named ice IX in 1963.

The STRUCTURE of ICE!

Ice is the solid state of water. The freezing point of water and melting point of ice are at 0*C. Since ice expands when frozen, it has a lower density compared to water; this is why ice floats in water.

-water expands when it freezes
-an increase of pressure lowers the melting point of ice.

Now at a pressure 100 times the normal atmospheric pressure, the melting point of ice is only about 1*C less than at normal pressure.

Allotropes are different variations of the molecule that exists in the same physical state.
Allotropes of ice are formed at higher pressures.

The ice wee see in drinks or skating rinks is called Ice 1 or Ice-h. Ice-h means that a hexagonal lattice occurs when the ice is frozen or is in the form of snow.

There are eight other known allotropes of ice. They are named from "Ice II" to "Ice IX".

ie. <Ice II, Ice III, Ice IV, Ice V, Ice VI, Ice VII, Ice VIII, and Ice IX>.

These allotropes are created in laboratories.
Also, these allotropes are denser than water and their melting points rise with increased pressure.

-At about 6000 atm (about 6200 kg per sq cm) the melting point is still 0*C and at a pressure of 20,000 atm (about 20,700 kg per sq cm) the melting point rises above 80*C.
(Physics Encyclopedia, "Allotropes of Ice", 1998)

The hexagonal crystal structure of Ice I
aka "Ordinary ICE"

~~~E-Quote for the Allotropes of ice:

"Except at temperatures lower than those occurring naturally on the earth, none of these ices can exist at pressures of less than 2000 atm. Since the thickest ice sheet in the world - in Antarctica - is less than 4000 m thick, corresponding to a maximum pressure at the base of the ice of about 350 atm, it is clear that none of these artificial ices can normally exist on the earth."
~~(Pounder, 1965, p. 10)

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