Glaciers and Icebergs
A glacier is a large mass of ice moving slowly over some land surface or down a valley, formed over long periods from the accumulation of snow in areas where the amount of snow that falls exceeds the amount that melts. The word glacier comes from French via the Vulgar Latin glacier, and ultimately from Latin glacies meaning ice.
Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water. Glaciers cover vast areas of the polar regions and are found in mountain ranges of every continent except Australia, although there are glaciers on New Zealand. In the tropics glaciers are restricted to the highest mountains. The processes and landforms caused by glaciers and related to them are referred to as glacial. The process of glacier growth and establishment is called glaciation. Glaciers are sensitive monitors of climate conditions and are crucial to both world water resources and sea level variation.
Glacier Wikipedia
The first to explain the formation of icebergs was the Russian peasant prodigy Mikhail Lomonosov. In the 20th century, several scientific bodies were established to study and monitor the icebergs. The International Ice Patrol, formed in 1914 in response to the Titanic disaster, monitors iceberg dangers near the Grand Banks of Newfoundland and provide the "limits of all known ice" in that vicinity to the maritime community.
Icebergs are a mass of ice that has become detached, or calved, from the edge of an ice sheet or glacier and is floating on the ocean. Because ice is slightly less dense than water about one ninth of the total mass of a berg projects above the water.
Icebergs differ from other ocean ices: sea ice is formed directly from the freezing of ocean water; pack ice is tightly packed fragments of sea ice; ice floes are small, floating ice fragments that separate from pack ice. Fast ice - is ice attached to a shore.
Icebergs are mostly white because the ice is full of tiny air bubbles. The bubble surfaces reflect white light giving the iceberg an overall white appearance. Ice that is bubble free has a blue tint which is due to the same light phenomenon that tints the sky.
The bluish streaks of clear, bubble free ice often seen in icebergs results from the refreezing of meltwater which fills crevasses formed in the glacier as it creeps over land. The ice is blue because of the natural light scattering characteristics of pure ice. Occasionally airborne dust or dirt eroded from land ends up on the glacier surface eventually forming a noticeably darkened brown or black layer (in any orientation) within the ice of a floating iceberg.
Greenland is the source of most of the icebergs in the N Atlantic, where the iceberg season lasts roughly from February to October. Greenland and other N Atlantic icebergs are usually peaked and irregular in shape; Antarctic icebergs are tabular, with flat tops and steep sides.
Before the development of radar, sonar, and the Global Positioning System, sailors on watch in the Arctic region would listen for distinctive sounds to help them determine whether icebergs were close or far away.
As a consequence of the loss of the Titanic through collision with an iceberg in 1912, a patrol of N Atlantic shipping channels was initiated in 1914 by the international agreement of 16 nations.
Patrols use planes and surface vessels equipped with radar, loran, and underwater sound equipment. A constant census of bergs is maintained, and the location of an iceberg is reported to any ship in its vicinity.
A fantastic variety of shapes result from the deterioration process of icebergs. Despite the fact that no two icebergs are the same, there are certain categories of shapes that are used for iceberg observation. Often the terms; tabular, blocky, wedge, dome, pinnacle, and drydock are used.
For those who wish to look beyond the beauty of icebergs there are many things to look for which can make iceberg watching more interesting. Besides estimating the iceberg's size and shape there are many features which may be noted. Colored streaks, caves and tunnels, old and new waterline notches, even objects such as boulders or birds are seen on icebergs. Even more spectacular is the occasion of an iceberg calving and rolling which can often be heard from a good distance.
Icebergs Wikipedia
When Glaciers Melt, What's in the Water? Live Science - March 5, 2010
Ice Once Covered the Equator Live Science - March 5, 2010
"Snowball Earth" Confirmed: Ice Covered Equator National Geographic - March 5, 2010
But volcanoes would've made Earth more mud ball than snowball, scientists say.
Earth's now steamy Equator was covered with ice 716 million years ago.
Were short warm periods typical for transitions between interglacial and glacial epochs? PhysOrg - March 2, 2010
Research team breaks the ice with new estimate of glacier melt PhysOrg - March 2, 2010
Glaciers discovered in 'cursed' mountains of Albania PhysOrg - January 28, 2010
Cave reveals Southwest's abrupt climate swings during Ice Age PhysOrg - January 20, 2010
Earth's Polar Ice Sheets Vulnerable to Even Moderate Global Warming; New Orleans, Much of Southern Florida, Expected to Be Permanently Submerged Science Daily - December 17, 2009
Greenland Glaciers: Water Flowing Beneath Ice Plays More Complex Role Science Daily - December 16, 2009
Life's Ancient Island in the Ice PhysOrg - October 29, 2009
During the last ice age, massive glaciers covered much of our planet. However, a region of Alaska, Siberia and the Canadian Yukon remained ice-free. This region, known as Beringia, supported unique organisms and was an important haven for evolution. Now, scientists may have uncovered how Beringia supported such diversity at a time when conditions for life were harsh.
Melting Kyrgyz glaciers pose threat BBC - October 28, 2009
Melting Glaciers Behind Mysterious Increase in Pollution Live Science - October 21, 2009
Melting of the Greenland ice sheet mapped PhysOrg - September 16, 2009
The mysterious glaciers that grew when Asia heated up PhysOrg - August 27, 2009
Mystery Glaciers Growing As Most Others Retreat National Geographic - June 23, 2009
Himalayan glacier studies commence BBC - June 23, 2009
Ice Sheets Can Retreat 'In a Geologic Instant,' Study of Prehistoric Glacier Shows PhysOrg - June 21, 2009
Argentine glacier advances despite global warming AP - June 15, 2009
Silk Road threatened by melting glaciers New Scientist - June 15, 2009
Major ice-shelf loss for Canada BBC - September 3, 2008
Greenland melt could see huge sea-level rises New Scientist - September 3, 2008
Last Ice Age happened in less than year say scientists Scotsman.com - August 3, 2008
The last ice age 13,000 years ago took hold in just one year, more
than ten times quicker than previously believed, scientists have warned.
Canadian Arctic sheds ice chunk BBC - July 30, 2008
A large chunk of an Arctic ice shelf has broken free of the northern Canadian coast, scientists say.
Ice Remained Even When Earth Was Hot Live Science - July 29, 2008
Ice Adrift From Warming Scrapes Antarctic Seabed Bare National Geographic - July 18, 2008
"Mountains of the Moon" Glaciers Melting in Africa National Geographic - March 26, 2008
Giant Antarctic Ice Shelf Collapses National Geographic - March 26, 2008
A chunk of Antarctic ice about seven times the size of Manhattan
suddenly collapsed, putting an even greater portion of glacial ice at risk.
Video: Antarctica Ice Collapses National Geographic - March 27, 2008
Huge Iceberg Splits In Southern Atlantic Ocean Science Daily - March 17, 2008
Antarctic Icebergs Teeming With Life, Study Says National Geographic - June 22, 2007
Icebergs are 'ecological hotspot' BBC - June 22, 2007
Drifting icebergs are "ecological hotspots" that enable the surrounding
waters to absorb an increased volume of carbon dioxide, a study suggests
Scientists discover singing iceberg in Antarctica - MSNBC - November 25, 2005
Between July and November 2002 researchers picked up acoustic signals of unprecedented clarity when recording seismic signals to measure earthquakes and tectonic movements on the Ekstroem ice shelf on Antarctica's South Atlantic coast. Tracking the signal, the scientists found a 30-by-12-mile (50-by-20-kilometer) iceberg that had collided with an underwater peninsula and was slowly scraping around it."Once the iceberg stuck fast on the seabed it was like a rock in a river," said scientist Vera Schlindwein. "The water pushes through its crevasses and tunnels at high pressure and the iceberg starts singing. The tune even goes up and down, just like a real song."
Listen to the iceberg News in Science - November 25, 2005
Sound waves from the iceberg had a frequency of around
0.5 hertz, too low to be heard by humans. But by playing
them at higher speed the iceberg sounds like a swarm of
bees or an orchestra warming up, the scientists say.
How Ice Melts: Longstanding Mystery Solved Live Science - July 1, 2005
Antarctic glaciers show retreat BBC - April 2005
Pile-up as berg hits Antarctica BBC - April 2005
Scientists Discover Why The North Pole Is Frozen Science Daily - March 2005
Giant ice slabs set for collision BBC - January 2005
NASA looks at the current meltdown - Antarctica NASA - January 2005
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