Sunday, March 01, 2009

Icebergs

Bishop David Bena of the Convocation of Anglicans in North America used icebergs as an illustration on the Christian life in this morning's sermon at St. Andrew's Anglican Church in Vestal. It went something like this:

Icebergs off Greenland come in many shapes and sizes. Large icebergs can weigh millions of tons and they are moved by deep sea currents. Small bergs are pushed around by the wind and waves. We need to be like the large icebergs, moved by the currents of God's Spirit rather than the winds and waves that push around small icebergs.


From Iceberg information, Dr. Stephen E. Bruneau Ph.D., P.Eng:

A majority of the icebergs in the North Atlantic come from about 100 iceberg producing glaciers along the Greenland coast while a few originate in the Eastern Canadian Arctic Islands. The glaciers of western Greenland, where 90% of Newfoundland's icebergs originate, are amongst the fastest moving in the world, up to 7 km per year. The icebergs we see off Newfoundland are carried south in the cold Labrador current.

Icebergs off the coast of Newfoundland and Labrador range in size from massive tabular and blocky bergs in excess of several million tonnes to small bergs weighing 1% of this. Categories of iceberg sizes which are used for recording iceberg statistics range from very large (greater than 10 million tonnes and hundreds of meters long) to large, medium and small bergs and on to bergy bits then growlers, which are grand piano size pieces. Note that the average iceberg weight for the Grand Banks area is one to two hundred thousand tonnes, and is about the size of a cubic 15 storey building.

The "tip of the iceberg" expression can be explained as follows: Icebergs float because the density of ice (around 900 kg per cubic meter) is lower than that of seawater (around 1025 kg per cubic meter). The ratio of these densities tells us that 7/8 of the iceberg's mass must be below water. Usually icebergs are 20% to 30% longer under the water than above and not quite as deep as they are long at the waterline.

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