• The largest glacier in the world, Antarctica's Lambert Glacier, is one of the world’s fastest-moving ice streams. (Ice streams are parts of an ice sheet that move faster than the sheet as a whole.) Glaciers, like Lambert Glacier and other ice streams, are sometimes nicknamed “rivers of ice,” because—just like rivers—they flow from places of high elevation to low elevation. Glaciers flow with frozen water, while rivers flow with liquid. Lambert Glacier flows from the Antarctic ice sheet (on the interior of the continent) to the Amery ice shelf, a narrow inlet in East Antarctica. 
     
    Information used in this map of Lambert Glacier was gathered with remote sensing technology. Remote sensing technology collects data about an object without making physical contact with it. To study Lambert Glacier, researchers relied on data collected using instruments on the Radarsat-1 satellite. The glacier is simply too isolated to conduct extensive surveys in situ (in person).
     
    This map tracks the movement, or flow, of Lambert Glacier. Yellow represents areas of the Antarctic ice sheet with no real movement, including areas of exposed ground with no ice cover at all. Green areas move 100-300 meters (330-980 feet) per year. Most of the Lambert Glacier moves between 400-800 meters (1,310-2,620 feet) per year. As the glacier extends across Amery ice shelf, velocities increase to 1000-1200 meters (3,280-3,937 feet) per year.
    1. This image tracks the velocities of Lambert Glacier. Velocity is the rate of change in the position of an object—in this case, the glacier. Velocity is not the same thing as speed, although the two are closely related. Speed describes how fast an object is moving, while velocity also indicates the direction an object is moving. Why would scientists choose to measure the velocity, and not the speed, of Lambert Glacier? 

      Velocity allows scientists to calculate how different ice flows feed into the Lambert Glacier, and how the glacier moves across the ice shelf. Speed would only calculate how fast the glacier moved.

    2. The velocities of Lambert Glacier were calculated using a method called radar interferometry. Interferometric instruments on Radarsat-1 transmitted radiation to the targeted area on the glacier, which then reflected the radiation back into space. Other instruments on the satellite measured the reflected radiation. (This is the data used in the map.) Besides interferometry, what other methods of measurement evaluate signals reflected, or bounced back, from a transmitter? Where are these methods used?

      Interferometry is similar to radar and sonar techniques. Radar measures radio waves, and is frequently used in astronomy, meteorology, and communications. Sonar measures sound waves, and is often used in oceanography and underwater navigation.

    3. Scientists plotted their information on the velocity of Lambert Glacier on a map. How else could scientists have expressed this information? 

      Scientists could have used a graph or chart to measure the increasing and decreasing velocities of the glacier. They could track the location where each measurement was taken on one axis, and the velocity of the glacier at each location on the other.

  • Term Part of Speech Definition Encyclopedic Entry
    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    data Plural Noun

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

    DOGSTAILS Noun

    acronym for parts of a map: Date, Orientation, Grid, Scale, Title, Author, Index, Legend, Sources.

    elevation Noun

    height above or below sea level.

    Encyclopedic Entry: elevation
    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    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.

    ice stream Noun

    part of an ice sheet that moves faster than the ice around it.

    inlet Noun

    small indentation in a shoreline.

    isolate Verb

    to set one thing or organism apart from others.

    remote sensing Noun

    methods of information-gathering about the Earth's surface from a distance.

    satellite Noun

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

    survey Noun

    a study or analysis of characteristics of an area or a population.

    technology Noun

    the science of using tools and complex machines to make human life easier or more profitable.

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