Chapter 9: The Cryosphere

What factors could influence solar heating of Earth and glacial episodes?

-change in solar output (reflected in sunspot activity_ -increase in reflectivity (albedo) from snow or clouds causes cooling -release of greenhouse gases by volcanoes can trap more heat -volcanic ash and dust reflect solar radiation back into space, causing cooling

How snow and ice accumulate in glaciers

-snowflakes pressed together by weight of other snowflakes -more snow adds weight and compresses flakes into small spheres -increasing depth and pressure cause snow to become crystalline ice; commonly bluish from trapped air

Characteristics of a glacier

1. moving mass of ice, with rocks and finer sediment 2. cover broad areas or confined to valleys 3. Flow from higher elevations to lower ones 4. can merge becoming a wider, thicker glacier 5. forms depends on snowfall, temp., direction, and steepness of slopes

Since 1979 more than ___ of the polar ice cap has melted away

20%

What percent of Greenland and Antarctica includes Earth's glaciers?

95%

Accumulation of snow

> seasonal melt is main contributor to glaciers and ice caps

____ is covered by a vast, thick ice sheet, and sea ice forms a ring around it

Antarctica

The North Pole is within the deep ___ whig is mostly covered by sea ice

Arctic Ocean

Accumulation

The additions of mass of a glacier

Ablation

The loss of mass from a glacier

Interglacial period

a time in the past when both the climate and global ice cover were similar to those of today; ice sheets retreat, sea level rises

Lower Zone

ablation area; region of net loss where bare ice and old snow are exposed because the previous winter's snow cover has melted away

Upper zone

accumulation area, the part of glacier covered by remnants of the previous wirer's snowfall and is an area of net gain in mass

Earth's tilt: present day

adjusting back from maximum

Permafrost

characterizes periglacial regions; the active layer thaw in summer, becoming unstable, and refreezes in winter -when it melts, ground collapses

Kettle

closed basin

Ice cores

contain gas bubbles that give us samples of Earth's atmosphere to 100,000 years ago (records of climates)

Ice sheets

continent-size; cover nearly all the land within their margins

Earth's tilt: minimum

cooler summers, less melting, and more glaciers

Ice cap

cover mountain highlands or low lying land at high latitudes, flow radially out

Esker

curved ridge of sand and gravel

Outwash

debris reworked, transported and deposited by meltwater

Crevasse

deep, gaping fissure in the upper surface of a glacier

Terminus

end of the glacier; shifts in response to changes in the mass balance

Valley glacier

extends down-valley from a cirque

Sea Ice

forms by freezing of fresh water at the ocean surface, salt crystals are excluded

How do glaciers form?

from snow that accumulates and compacts until it is so dense that it is impenetrable to air (glacier ice=rock)

Pingoes

frost-heaved hills

Moraines

glacially bulldozed ridges of sediment

Fjord glacier

glacier in a marine coastal valley

Ice shelves

hundreds of meters thick occupy Antarctica's embayments

Patterned ground

ice-wedge polygons formed in the active layer as a result of cyclical freezing

Periglacial

land beyond the limit of glaciers and is mainly found i circumpolar regions

Gelifluction

mass wasting

Cirque glacier

occupies bowl-shaped depression

During glacial periods...

ocean becomes saltier

Cryosphere

part of Earth's surface that remains perennially frozen -sea ice -glaciers: 10% of earth's land surface -frozen ground: 20% of earth's land

Highly reflective surface (high albedo)

reflects sunlight back into spar, reducing surface air temperature

Drumlins

ridges of sediment or bedrock parallel to the direction of ice flow

During interglacials...

sea ice melts and ocean becomes less salty

Eccentricity

shape of orbit; influences global climate

A glaciers advance or retreat is the balance of the amount of ____.

snow and ice added and lost

Piedmont glacier

spreads out form a valley glacier onto a lowland

Equilibrium line

the boundary between the accumulation area and the ablation area -coincides with the local snow line

Snowline

the lower limit of perennial snow

Glaciation

the modification of the land surface by the action of glacier ice (also called ice age, glacial periods, and glacial stages)

Calving

the progressive breaking off of icebergs from the form of a glacier that terminates in deep water

Till

unsorted glacial debris deposited by ice

Earth's tilt: maximum

warmer summers near poles, more melting, and less glaciation

Glaciers

when snow and ice become so thick that gravity causes the frozen mass to move

Precession

wobble of rotation axis; influences global climate