Sea Ice Formation and Movement

Sea Ice Formation and Dynamics

• Sea ice forms when the ocean surface cools to seawater’s freezing point, impacting global ocean circulation and climate.
• Constant motion of sea ice is driven by winds and ocean currents, leading to structural changes.
• Divergent movement causes ice to break, forming linear openings called leads.
• Large areas of open water within sea ice are referred to as polynyas.
• Fractured ice shears and piles into raised formations known as pressure ridges.
• Freezing seawater excludes salt, generating cold, saline, and denser water that contributes to deep ocean water formation, such as Antarctic Bottom Water.

Periglacial Landscapes

• Periglacial zones are land areas beyond glacial limits where temperature and frost significantly shape landscapes.
• Permafrost is perennially frozen ground, consisting of soil, sediment, and bedrock, remaining below freezing for extended periods (-5° to -10°C).
• Most permafrost formed during the last glacial age, with notable fossils of woolly mammoths found within.
• In summer, the active layer of permafrost thaws, creating land surface instability and movement.

Glacial Deposits

• Glacial movement results in the deposition of materials beyond the equilibrium line.
• Till directly deposited on the ground surface is called basal till.
• End moraines, which are ridge-like sediment accumulations along glacier margins, consist of two types: terminal moraine and lateral moraine.
• Outwash refers to material transported and deposited by glacial melt-water.
• Moraines lead to specific landforms, including kames (small stratified hills) and kettles (closed basins from melting glacial ice).

Earth's Snow and Ice Cover

• The ocean's vast expanses give Earth its bluish color from space, contrasting with the polar regions' white snow and ice cover.
• In the northern hemisphere, ice floats as a thin sheet on the Arctic Ocean.
• The southern hemisphere features a vast glacier system over Antarctica, with surrounding floating sea ice extending beyond the coastline.
• Polar ice contributes to the generation of cold, dense water critical for deep ocean circulation and climate regulation.
• The cryosphere, accounting for nearly one-third of the Earth's land surface, includes glaciers, sea ice, and frozen ground.
• Components of the cryosphere encompass:
  • Greenland Ice Sheet
  • Antarctic Ice Sheet
  • Ice shelves
  • Sea ice
  • Permafrost
  • Mountain-based ice caps and smaller glaciers

Snow Coverage

• The greatest snow cover occurs in continental climates at middle and high latitudes, and in high-altitude regions.
• The snowline defines the lower boundary of snow within the annual snow cycle, influenced by altitude, temperature, and moisture availability.

Water Chemistry of Groundwater

• Groundwater commonly contains dissolved minerals and compounds derived from weathered rock material.
• Groundwater that traverses limestone is rich in calcium and magnesium bicarbonates, termed hard water, which does not lather with soap.
• Soft water contains minimal dissolved matter with negligible calcium content.
• The mineral content of spring water reflects the geological strata where it sources its minerals over varying time scales.

Geological Work of Groundwater

• Rainwater’s slight acidity enables it to dissolve calcite, leading to the creation of karst landscapes featuring caves and sinkholes.