• iceberg
    Antarctica and Greenland, home to the world's ice sheets, are the chief source of the world's icebergs.

    Iceberg Prose
    The American novelist Ernest Hemingway is famous for his writing style of short sentences. Hemingway, in fact, compared his writing style to icebergs. Just like an iceberg remains largely unseen beneath the surface, a writer can leave parts of a story unwritten. Hemingway believed the reader would understand and be affected by the unwritten parts of a story as well as parts that were actually written.

    Why So Blue?
    Some glaciers and icebergs are blue, for the same reason water is blue. The chemical bond between oxygen and hydrogen in water absorbs light in the red end of the visible light spectrum.

    Blue glaciers and icebergs are not blue for the same reason the sky is blue. The sky is blue due to atmospheric scattering of light (Raleigh scattering), a different phenomenon.

    Icebergs are large chunks of ice that break off from glaciers. This process is called calvin. Icebergs float in the ocean, but are made of frozen freshwater, not saltwater.

    Most icebergs in the Northern Hemisphere break off from glaciers in Greenland. Sometimes they drift south with currents into the North Atlantic Ocean. Icebergs also calve from glaciers in Alaska.

    In the Southern Hemisphere, almost all icebergs calve from the continent of Antarctica.

    Some icebergs are small. Bergy bits are floating sea ice that stretch no more than 5 meters (16.5 feet) above the ocean. Growlers are even smaller.

    Icebergs can also be huge. Some icebergs near Antarctica can be as big as Sicily, the largest island in the Mediterranean Sea. As little as one-eighth of an iceberg is visible above the water. Most of the mass of an iceberg lies below the surface of the water. This is where the phrase "tip of the iceberg" came from, meaning only part of an idea or problem is known.

    There are many different kinds of icebergs. Brash ice, for instance, is a collection of floating ice and icebergs no more than 2 meters (6.5 feet) across. A tabular berg is a flat-topped iceberg that usually forms as ice breaks directly off an ice sheet or ice shelf.

    The ice below the water is dangerous to ships. The sharp, hidden ice can easily tear a hole in the bottom of a ship. A particularly treacherous part of the North Atlantic has come to be known as Iceberg Alley because of the high number of icebergs that find their way there. Iceberg Alley is located 250 miles east and southeast of Newfoundland, Canada.

    In 1912, the Titanic, a large British ocean liner on its way to New York, struck an iceberg and sank in Iceberg Alley. More than 1,500 people drowned. Soon after the Titanic sank, an International Ice Patrol was established to track icebergs and warn ships. That patrol continues today.

    Iceberg patrols now use global positioning system (GPS) technology to help locate icebergs and prevent more tragedies like the Titanic. In 1999, the National Ice Center lost track of an iceberg the size of Rhode Island. It was found drifting toward the Drake Passage, an important shipping route south of Argentina. Dr. David Long of NASA's SeaWinds science team used satellite data to track the iceberg, the first time satellite technology was used for that purpose. Since that time, the SeaWinds team has used satellites to track the world's ice.

    Icebergs that drift into warmer waters eventually melt. Scientists estimate the lifespan of an iceberg, from first snowfall on a glacier to final melting in the ocean, to be as long as 3,000 years.

  • Term Part of Speech Definition Encyclopedic Entry
    bergy bit Noun

    sea ice floating not more than 5 meters (16.5 feet) above the ocean, and not more than 10 meters (33 feet) across.

    brash ice Noun

    floating fragments of ice and icebergs no more than 2 meters (6.5 feet) across.

    calving Noun

    process where a glacier cracks and breaks apart.

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    current Noun

    steady, predictable flow of fluid within a larger body of that fluid.

    Encyclopedic Entry: current
    data Plural Noun

    (singular: datum) information collected during a scientific study.

    Ernest Hemingway Noun

    (1899-1961) American author and journalist.

    estimate Verb

    to guess based on knowledge of the situation or object.

    freshwater Noun

    water that is not salty.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    Global Positioning System (GPS) Noun

    system of satellites and receiving devices used to determine the location of something on Earth.

    growler Noun

    small chunk of floating sea ice, extending less than one meter (3.3 feet) above the ocean, and fewer than five meters (16 feet) in length.

    ice Noun

    water in its solid form.

    Encyclopedic Entry: ice
    iceberg Noun

    large chunks of ice that break off from glaciers and float in the ocean.

    Encyclopedic Entry: iceberg
    Iceberg Alley Noun

    area in the North Atlantic Ocean with a large number of icebergs.

    ice sheet Noun

    thick layer of glacial ice that covers a large area of land.

    Encyclopedic Entry: ice sheet
    ice shelf Noun

    mass of ice that floats on the ocean but remains attached to the coast.

    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    lifespan Noun

    length of time from when an organism is born to when it dies.

    ocean liner Noun

    large ship used to transport people or goods to and from ocean ports on established routes, or lines.

    satellite Noun

    object that orbits around something else. Satellites can be natural, like moons, or made by people.

    shipping route Noun

    path in a body of water used for trade.

    snowfall Noun

    amount of snow at a specific place over a specific period of time.

    tabular berg Noun

    flat-topped iceberg, usually formed by ice breaking off from an ice shelf.

    Titanic Noun

    luxury cruise ship that sank in the North Atlantic Ocean in 1912.

    treacherous Adjective

    very dangerous.