Like fishing or bird watching, iceberg watching is a hobby that draws some people back to their favorite viewing location year after year. A choice place to observe icebergs in North America is from the Canadian island of Newfoundland - the most eastern point in North America. In a given year, between 500 and 1,000 icebergs drift past Newfoundland's capital city of St. Johns (about 48 degrees north latitude). A guided boat tour from any number of seaside towns will give you the best view of the bergs, and if you're lucky, you should be able to see a few whales as well. Better yet, you don't have to visit Newfoundland in the dead of winter to see them. There's usually plenty of icebergs around even in June and July.

The principal iceberg-producing area in the Arctic is along the west coast of Greenland. Approximately 40,000 icebergs each year calve or break off from the Greenland Ice Cap and other smaller ice sheets in the Arctic, such as Ellesmere Island, to the west of Greenland. Greenland accounts for upwards of 85% of the icebergs that reach Newfoundland. Icebergs that calve in this region may initially drift northwest with the Northwest Greenland Current before they encounter the stronger Labrador Current, which pushes them towards the south into the waters of the Atlantic Ocean. The area to the north and east of Newfoundland is a collection area for icebergs. Locals refer to the area off the northern tip of this island as "iceberg alley." The journey an iceberg takes from the time it calves from a glacier off of western Greenland until it reaches Newfoundland, may take 2 or 3 years.

Many icebergs are breathtakingly beautiful - fragmented shapes of brilliant white ice with sometimes jade or turquoise highlights. The unusual shapes are caused by weathering effects - erosion by waves, wind and melting. Multiple scattering of light in the glacial ice produces the blue and green hues. Red light is scattered a bit more by snow and ice crystals than is the shorter wavelength blue light. After the sunlight is scattered by enough crystals, most all of the red light is removed, leaving only blue light. After more scattering, the blue light turns to dark blue, and the deeper the ice the deeper the blue becomes. This phenomenon is easy to see when you poke a stick into a snow that's more than a foot or so deep. This year, even in the northern US, you would be hard pressed to find any snow this deep. The greenish appearance of some icebergs probably results from the bluish light mixing with reddish light that occurs when the Sun is low in the sky, near sunset for instance.

Since the snow that formed the ice that eventually becomes an iceberg was originally, relatively free from impurities, a big iceberg, the size of a city block for example, could provide a source of clean drinking water for a city of 50,000 people for perhaps ten years or more. Although, there have been several schemes to try to tow huge icebergs to areas where fresh water is scarce, they're proven to be impractical and or extremely expensive. Thus, to date, non of them have been implemented.

Although icebergs are considered to be fresh ice, inasmuch as they're newly broken off from glaciers that may be 15,000 thousand years old, they're not exactly pure ice. In fact, while from a distance icebergs look bright and clean, upon closer inspection, many icebergs are rather dirty, at least on the surface. The contrast between the sea, having a low albedo (brightness) and the ice having a rather high albedo, gives the illusion that icebergs are sparkling clean. However, wind-blown dust, algae and even contaminants from industrial complexes thousands of miles away may settle on the bergs. Though the core of an iceberg may be composed of very clean ice, the surface of an old berg can be rather grimy.

While it's the tip of the iceberg that we see, most of the berg itself is submerged. Usually, only about 1/7 or 1/8 of the mass of an iceberg is above the surface of the water. However, this doesn't mean that the submerged portion is 7 times deeper then the height of the above-water ice. If the visible part of an iceberg is 100 ft high (31 m), the submerged part may extend 125 feet (38 m) beneath the water. The point is, ice is slightly less dense than water (92% of the density of water), so it floats with most of its mass below the surface. On the other hand, a piece of cork having a density only about 20% that of water floats close to the water surface.

Some of the icebergs that have broken off of the Antarctic ice shelves have been monsters - one was the size of the state of Conneticut! In the Arctic, the biggest iceberg thus far recorded was estimated to be about 7 miles (11.2 km) long and 3 1/2 miles (5.6 km) wide. This giant was spotted near Baffin Island in 1882. Car or house-sized icebergs are sometimes called "growlers." The smallest icebergs are known as "bergy bits," and these little fellas can be dangerous in shipping lanes since they're not easy to spot, even with radar. Along the coast of Newfoundland, it's not uncommon to see icebergs that soar 150 feet (46 m) or more above the water line, and in 1967 a magnificent berg topped out at approximately 550 feet (169 m) - the height of the Washington Monument in Washington DC.

Of course, icebergs and ships don't get along very well. Eighty years ago this April, an iceberg drifting some 400 miles (640 km) southeast of Newfoundland, made Titantic part of history. The latitude of the Titantic was about 42 degrees N (about the same latitude as Boston) when it hit the iceberg. It may seem surprising that an iceberg made it that far south, but it's actually not all that uncommon. Most of the bergs that make it to Newfoundland have already been in the sea for a couple of years and are in the final throws of melt down. Once they reach the warmer waters associated with the Gulf Stream, they quickly break apart. However, on occasion, an iceberg on two has been sighted near Bermuda (about 32 degrees north latitude).

The number of icebergs which make it south of the 50 degree parallel varies from one year to the next. In 1929, over 1000 icebergs were observed by the International Ice Patrol (set up as a result of the loss of the Titantic), whereas in 1966 none was sighted. This variation is related more to the level of activity in the iceberg calving areas than to climate or other factors.

For more about Newfoundland Icebergs see http://www.discovernorthland.com
For more about the Titantic, see the science question for April 16, 1998.