THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Tuesday, August 22, 1995 TAG: 9508220392
SECTION: FRONT PAGE: A4 EDITION: FINAL
SOURCE: BY CHARLENE CASON, STAFF WRITER
LENGTH: Medium: 54 lines
Icebergs start out as part of 20 major glaciers that cover the western side of Greenland. Ninety-five percent of the island is covered in ice. Each year about 10,000 to 15,000 chunks of ice break off, or are ``calved,'' into Baffin Bay.
Roughly 85 percent of these icebergs are carried along the Baffin and Labrador currents; of those, at least 1,500 eventually end up drifting along the Grand Banks of Newfoundland. These are the icebergs that pose the greatest maritime threat, and the ones tracked by the International Ice Patrol.
Most people have learned in school that only one-tenth of an iceberg shows above the water. An aerial view of the block will reveal, with a brilliant blue perimeter, where the other nine-tenths begins underwater.
Oceanographers classify icebergs as extra-large, large, medium and small. The extra-large ice can be up to a mile long and 500 feet high - above the water. The area that shows may appear pointed one day and flat the next. This is because the mountainous masses can flip over, completely changing their appearance. The turning process takes 24 to 48 hours.
Medium-sized icebergs, called ``growlers,'' are potentially the most dangerous. Normally only the size of a grand piano on the surface, they do not make good radar contacts. This means the deadliest 90 percent of their mass may never be detected by the ice patrol. Small icebergs are called ``bergey bits.''
Icebergs have a two- to three-year ``life cycle,'' from spawning to death; they need a sea temperature of 2 degrees Celsius (35.6 Fahrenheit) to survive. Temperatures in the Labrador Current are generally 1 to 6 degrees Celsius.
Three things affect the changing size and shape of drifting icebergs: waves, sunshine and water temperature. Of these, waves cause the most change.
In addition to icebergs, sea ice - frozen waves or ice floes - also pose a threat to mariners. Canada, the United States' partner in the International Ice Patrol, is responsible for tracking sea ice, which appears only in the northernmost reaches of the Labrador Sea. Their mission covers Canadian waters, while the U.S. mission covers international waters. MEMO: Main story on page A1.
ILLUSTRATION: Photo by DREW C. WILSON, Staff
The International Iceberg Patrol spots two icebergs, standing up to
300 feet high, that are floating south toward North Atlantic
shipping lanes.
KEYWORDS: ICEBERG U.S. COAST GUARD by CNB