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band ogives

alternate bands of light and dark on a glacier; usually found below steep narrow icefalls and thought to be the result of different flow and ablation rates between summer and winter.

banded cryogenic fabric

a distinct soil micromorphology, resulting from the effects of freezing and thawing processes, in which soil particles form subhorizontal layers.


a barometer that records barometric pressure over time (days or weeks).


an instrument for measuring atmospheric pressure; two types of barometers are commonly used in meteorology: the mercury barometer and the aneroid barometer.


areas of discontinuous vegetation cover in the polar semi-desert of the high arctic.

basal cryopeg

a layer of unfrozen ground that is perennially cryotic (t < 0 degrees Celsius), forming the basal portion of the permafrost.

basal cryostructure

the cryostructure of a frozen deposit of boulders that is saturated with ice.

basal sliding

the sliding of a glacier over bedrock.

basal-layered cryostructure

the cryostructure of a frozen layered deposit of gravel and boulders that is saturated with ice.

beaded stream

a stream characterized by narrow reaches linking pools or small lakes.

Beaufort Gyre

an ocean and ice circulation pattern in the Beaufort Sea, north of Alaska. This gyre moves in a clockwise direction, fed by an average high-pressure system that fosters anti-cyclonic winds. Ice that forms in or drifts into the Beaufort Gyre has historically remained in the Arctic ice system for years, accumulating snow and thickening each winter. Beginning in the late 1990s, the ice began melting away while in the southern parts of the gyre, before completing the circulation.


hard-packed rock lying below the Earth’s surface; lies in beds or layers; can be variable across geographic space; above bedrock is a layer of broken, weathered rock.


a long area of pack ice from a few km to more than 100 kilometers in width.


crevasse that separates flowing ice from stagnant ice at the head of a glacier.
Explorer on Skillet Glacier in 1936. Bergschrund is visible as the dark band of ice in the background.

bergy bit

large chunk of glacier ice (a very small iceberg) floating in the sea; bergy bits are usually less than 5 meters (15 feet) in size and are generally spawned from disintegrating icebergs.

Bermuda high

the semipermanent subtropical high over the North Atlantic Ocean, especially when it is located over the western part of the ocean; the same high over the eastern part of the Atlantic is called the Azores high; on mean charts of sea level pressure, this high is one of the primary centers of action in northern latitudes.


situation of a vessel surrounded by ice and unable to move.


an extensive crescent-shaped indentation in the ice edge, formed either by wind or current.

blind lead

a lead closed off on all sides within the ice pack.


winds of at least 35 miles per hour along with considerable falling and/or blowing snow reducing visibility to less than one-quarter mile for a period of at least three hours (extremely cold temperatures are often associated with dangerous blizzard conditions, but are not a formal part of the modern definition).

block field

a surficial layer of angular shattered rocks formed in either modern or pleistocene periglacial environments.

blow hole

opening through a snow bridge into a crevasse or system of crevasses which are otherwise sealed by snow bridges; a snowdrift usuallly forms on the lee side.

blowing snow

an ensemble of snow particles raised by the wind to moderate or great heights above the ground; the horizontal visibility at eye level is generally very poor.


a cold wind blowing down an incline; a kind of katabatic wind.

boreal forest

the forested region that adjoins the tundra along the arctic tree line, which has two main divisions: its northern portion is a belt of taiga or boreal woodland, while its southern portion is a belt of true forest, mainly conifers but with some hardwoods; on its southern boundary the boreal forest passes into “mixed forest” or “parkland,” prairie, or steppe, depending on the rainfall.

bottom bergs

icebergs that originate from near the bottom of a glacier; the color is usually black from trapped rock material or dark blue because of old, coarse, bubble-free ice; they sit low in the water due to the weight of the embedded rocks.

bottom temperature of snow cover

temperature measured at the base of the snow cover during mid- to late-winter (February/March).

branched-valley glacier

glacier that has one or more tributary glaciers that flow into it; distinguished from a simple valley glacier that has only a single tributary glacier.
In this photograph from 1969, small glaciers flow into the larger Columbia Glacier from mountain valleys on both sides. Columbia Glacier flows out of the Chugach Mountains into Columbia Bay, Alaska. (Photo courtesy of the United States Geological Survey. Archived at the World Data Center for Glaciology, Boulder, CO.)

brash ice

accumulation of floating ice made up of fragments not more than 2 meters (6.6 feet) across, the wreckage of other forms of ice.


small droplets of highly saline water that form in pockets between ice crystals, as sea ice forms and expels salt into the underlying ocean water.

BTS method

method to predict the presence or absence of permafrost in a mountain area, using measurements of the bottom temperature of snow cover mid- to late-winter.


smooth hills of ice that form on the bottom of sea ice from eroding keels, particularly during the summer melt.

buoy weather station

a buoy, either fixed or floating, which carries instruments for sensing various meteorological elements and for transmitting the data by radio.

buried ice

ice formed or deposited on the ground surface and later covered by sediments.

Buys Ballots Law

Meterological law which states that if you are standing with your back to the wind in the Northern Hemisphere, low pressure will be on your left, and high pressure will be on your right. Ballot was a 19th century Dutch climatalogist.