(Discussion and Worksheet – The Cryosphere Part 1 Tuesday March 21, 2017 (Discussion and Worksheet – The Cryosphere Part 1

In addition to the oceans, where else is water found on Earth? The Launch Pad Tuesday, 3/20/18 In addition to the oceans, where else is water found on Earth? 1/1 lakes and reservoirs swamps rivers and streams glaciers and icecaps groundwater

Announcements Remediation for Quiz 13 begins today and runs through next Wednesday, March 28th.

3/6 QUIZ 13 3/7 3/28 F1 F2 S1 Assignment Tomorrow Next Wednesday, Summative or Formative # Date Issued Gone Missing Day Last Day Accepted eResearch Paper - Groundwater F1 3/6 Tomorrow Groundwater Worksheet Participation Grade F2 QUIZ 13 S1 3/7 Next Wednesday, 3/28

The Cryosphere Part 1

Cryosphere Vocabulary sea ice glacier valley (alpine) glacier ice sheet (continental glacier) Piedmont glacier ice cap frozen ground (which includes permafrost) deglaciation

The cryosphere is the portion of Earth's surface where water is in solid form. This includes areas of: sea ice glaciers ice caps ice sheets frozen ground (which includes permafrost.)

Cryosphere Facts The cryosphere has a wide overlap with the hydrosphere. The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in the global climate and in climate model response to global changes. The term deglaciation describes the retreat of cryospheric features.

Sea kayakers look at the face of McBride Glacier along Muir Inlet in Glacier Bay National Park, Alaska.

Glaciers Glaciers are part of both the hydrologic cycle and the rock cycle. A glacier is defined as a thick mass of ice that forms over land from the compaction and recrystallization of snow, and shows evidence of past or present flow.

Types of Glaciers Valley, or alpine glaciers form in mountainous areas and flow down relatively narrow valleys between the mountains.

Types of Glaciers Ice sheets, or continental glaciers, are very large. They are masses of ice covering more than 50 000 km².

The only present-day continental ice sheets are those covering Greenland and Antarctica. Their combined areas represent almost 10% of Earth’s land area. Figure 6.2

Types of Glaciers An ice cap is an ice mass that covers less than 50 000 km² of land area (usually covering a highland area.)

Types of Glaciers Piedmont glaciers are a type of glaciation characteristic of Alaska - large valley glaciers meet to form an almost stagnant sheet of ice.

Malaspina glacier in south-eastern Alaska is considered a classic example of a piedmont glacier. Piedmont glaciers occur where valley glaciers exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes.

Lambert Glacier is a major glacier in East Antarctica Lambert Glacier is a major glacier in East Antarctica. At about 60 miles wide, over 250 miles long, and about 2,500 m deep, it holds the Guinness world record for the world's largest glacier. It drains 8% of the Antarctic ice sheet to the east and south of the Prince Charles Mountains and flows northward to the Amery Ice Shelf.

Glaciation

This map shows a portion of North America’s present-day coastline compared to the coastline that existed during the last ice age maximum 18 000 years ago.

The North American coastline that would exist if present-day ice sheets in Greenland and Antarctica melted.

The Formation of Glacial Ice As air infiltrates fallen snow, the snowflakes become smaller, thicker, and more spherical. The air is forced out of the snow. The snow then recrystallizes into a much denser mass of small grains called firn. Once the thickness of the ice and snow exceeds 165 feet, firn fuses into a solid mass of interlocking ice crystals, which we call glacial ice.

Movement of Glacial Ice The movement of glacial ice is referred to as “flow.” One type of glacial flow is called plastic flow , and involves movement within the ice. Ice behaves as a brittle solid until the pressure upon it is equivalent to the weight of about 165 feet of ice. Once that load is surpassed, ice behaves as a plastic material and flow begins.

Movement of Glacial Ice A second and often equally important mechanism of glacial movement consists of the entire ice mass slipping along the ground. The lowest portions of most glaciers are thought to move by this sliding process.

Movement of Glacial Ice The upper 165 feet or so of a glacier is not under sufficient pressure to exhibit plastic flow. Rather, the ice in this upper-most zone is brittle and is referred to as the zone of fracture. The ice in this zone is carried along “piggyback” by the ice below. When the glacier moves over irregular terrain, the zone of fracture is subjected to tension, resulting in cracks called crevasses. These cracks can make travel across glaciers dangerous, and can extend to depths of 165 feet. Beyond this depth, plastic flow seals them off.

When a glacier moves across irregular terrain, crevasses form in the brittle portion.