Dynamic Planet

Glacier formation

The process of glaciers forming from accumulated snow, leading to ice due to compaction and pressure.

Ice I

The stable phase of ice found at ordinary pressures, prevalent in Earth's biosphere.

Hexagonal ice Ih

The common crystalline structure of ice with hexagonal symmetry.

Cubic ice Ic

A variant of ice with a crystal structure similar to that of diamond, formed at temperatures below 140°K.

Density of ice

Ice is approximately 8.3% less dense than liquid water, with specific densities at different temperatures.

Specific Heat Capacity

The amount of heat required to change a substance's temperature; ice has a specific heat capacity of 2093 Joules/kgC.

Basal Sliding

Movement of a glacier over its bed through the incorporation of meltwater at its base.

Regelation Flow

Melting of ice under pressure and refreezing when removed from the pressure, allowing movement around obstacles.

Basal Slip

A thin layer of meltwater at the glacier's base that lubricates flow.

Equilibrium/Firn Line

The line separating the accumulation and ablation zones of a glacier.

Zone of Ablation

The area where annual melting exceeds accumulation, resulting in glacier size reduction.

Glacial Mass-Balance

The difference between the mass gained from accumulation and lost from ablation in a glacier.

Névé

First-year glacial snow; partially melted and compacted, marking an early stage in glacier formation.

U-Shaped Valley

A valley formed by glacial erosion, characterized by its wide, flat bottom and steep sides.

Medial Moraine

A ridge of debris formed within the center of a glacier where two lateral moraines converge.

Drift

All sedimentary deposits of glacial origin; includes till and outwash.

Kettle Lakes

Lakes formed by the melting of blocks of glacial ice buried in sediment.

Isostatic rebound

The rise of land masses that were depressed by the weight of ice sheets during glaciation.

Milankovitch cycles

Natural variations in Earth's orbit affecting climate, influencing glacial and interglacial periods.

Subglacial lakes

Bodies of water located beneath glaciers, crucial for glacier dynamics.

Thermokarst lakes

Lakes formed when permafrost thaws, creating depressions that fill with water.

Calving

The process by which chunks of ice break off from the edges of glaciers or ice shelves.

Jökulhlaups

Glacial outburst floods that occur when a lake fed by glacial meltwater breaches its dam.

Pressure ridges

Features formed in sea ice where frozen floes are pushed against each other by wind and current.

Diamictite

Sedimentary rock composed of a mixture of unsorted particles, often deposited by glacial processes.

Erratics

Large boulders transported by glaciers and deposited far from their source.

Pingo

A mound of earth-covered ice found in permafrost regions, formed by the influx of water and freezing.

Ogives

Banded patterns on glacier surfaces formed from seasonal variations in snow accumulation.

Ice Shelf

Thick slabs of ice that extend from a glacier into the ocean, occurring in polar regions.

Firn

Granular snow that persists through summer, transitioning towards glacial ice.

Density of glacier ice

Glacier ice density ranges from about 830 to 923 kg/m^3, depending on the conditions.

Thickness of ice sheets

The thickness of major ice sheets like Greenland and Antarctica significantly influences sea level.

Albedo

The reflective quality of a surface; snow and ice have high albedo, affecting climate.

Lateral moraine

Material deposited on the side of a glacier, forming ridges.

Sublimation

The process of ice turning into vapor without becoming liquid, part of the ablation process.

Calafquen Lake

An example of a moraine-dammed lake in Chile.

Glacial striations

Scratches or grooves cut into bedrock by glacial abrasion.

Erratic boulders

Large rocks transported by glacier movement, differing in composition from local geology.

Antarctic ice shelves

Large floating extensions of ice sheets that play a critical role in stabilizing glaciers.

Permafrost

Ground that remains completely frozen for two or more consecutive years.

Active layer

The upper layer of permafrost that thaws during the summer and freezes again in winter.

Blockfields

Bouldery landscapes formed by freeze-thaw weathering and erosion of underlying bedrock.

Patterned ground

Geometric shapes formed in soil by freeze-thaw cycles of periglacial terrain.

Summit ice dome

A dome-shaped mass of ice, characteristic of ice caps.

First-year ice

Ice that has survived one winter season but is less than two winters old.

Fast ice

Sea ice that is attached to the shore or fastened to grounded icebergs.

Drift ice

Ice that is free to move with winds and currents across the ocean.

Nilas

A thin, flexible layer of young sea ice, first formed on the ocean surface.

Young ice

Sea ice that is thicker than nilas but has not survived a melting season.

Sediment transport

Movement of sediment from one place to another, often influenced by glacial processes.

Cryoconite holes

Holes in glacier surfaces created by dust and debris absorbing heat from sunlight.

Tidewater glaciers

Glaciers that terminate in the ocean, often characterized by rapid calving and melting.

Bergshrund

A large crevasse that forms where a stationary block of ice meets a moving block.

Ice stream

A fast-moving region of ice flow within an ice sheet, often draining significant ice masses.

Cirque glaciers

Small glaciers that form in bowl-shaped depressions in mountainous areas.

Paternoster lakes

A series of small lakes connected by a stream, resembling beads on a string.

Fracture patterns

The visible lines or cracks on glacial ice surfaces indicating stress and flow dynamics.

Subglacial hydrology

The study of water flow beneath glaciers, significant for understanding glacier movement.

Ice flow dynamics

The study of how glaciers move, influenced by gravity, temperature, pressure, and basal conditions.

Thermal regime

Classification of glaciers based on temperature and meltwater presence at their base.

Eccentricity

A measure of Earth's orbit shape, affecting solar insolation and climate patterns.

Obliquity

The tilt of Earth's axis, influencing seasonal climate and glaciation.

Precession

The change in direction of the Earth's rotational axis, affecting climate cycles over millennia.

Glacial retreat

The process of glaciers shrinking due to temperature increases and melting.

Pleistocene Epoch

The geological epoch characterized by repeated glaciations over the last 2.6 million years.

Laurentide Ice Sheet

A large ice sheet in North America during the last glacial maximum, shaping the Great Lakes.

Neoproterozoic Snowball Earth

A hypothesis that the Earth was entirely or nearly entirely frozen at least once during the Neoproterozoic.

Ice cap vs. Ice sheet

Ice caps are smaller than ice sheets, typically covering less than 50,000 square kilometers.

Marine isotope stages

Intervals of glacial and interglacial periods identified by oxygen isotope ratios in ice cores.

Eocene-Oligocene transition

A significant Earth climate transition marked by global cooling and the establishment of ice sheets.

Glacial isostatic adjustment

The rise of land masses that were depressed by the weight of ice sheets during glacial periods.

Greenland Ice Sheet

The second largest ice sheet in the world, covering most of Greenland, with significant sea level implications.

Antarctic Peninsula

The part of Antarctica that has experienced significant warming and ice shelf disintegration.

Frazil ice

Small ice crystals that form in supercooled water, leading to sea ice formation.

Finger lakes

A group of long, narrow lakes formed by glacial activity, typical of New York.

Drift ice

Sea ice that is free to drift with wind and current, often forming large floes.

Ice floe

A large piece of floating sea ice, typically 20 meters or more across.

Ice shelf buttressing

The effect of ice shelves in slowing down the flow of the grounded ice behind them.

Thermal choke

A situation where meltwater cannot drain from under a glacier, leading to destabilization.

Climate feedback loop

Processes that amplify or diminish effects of changes in climate, such as melting ice leading to albedo changes.