Geography Test Thursday Flashcards
Accumulation
- Definition: The process of adding mass to a glacier primarily through precipitation.
- Type of Precipitation: Mainly occurs as snow or hail.
- Location: Predominantly at higher altitudes at the glacier’s source.
Ablation
- Definition: The loss of mass from a glacier.
- Processes Included: Melting, evaporation, sublimation, calving, and avalanches.
Glacial Budget
- Definition: The balance between accumulation and ablation in a glacier.
- Importance: Indicates whether a glacier is stable, advancing, or retreating.
Positive Glacial Budget
- Condition: Occurs when accumulation exceeds ablation.
- Outcome: The glacier advances and increases in mass.
Negative Glacial Budget
- Condition: Occurs when ablation exceeds accumulation.
- Outcome: The glacier retreats and decreases in mass.
Seasonal Budget Fluctuations
Observation: Glacial budgets change annually with more ablation in summer and more accumulation in winter.
System Interactions
- Definition: Glaciers function as natural systems with specific
interactions. - Input-Process-Output Model: Inputs lead to processes, producing outputs that affect glacier mass.
Open System Characteristics
- Definition: A system with external inputs.
- Examples of Inputs: Precipitation, avalanches from neighboring areas.
Closed System Characteristics
- Definition: A self-contained system where all processes happen within the defined area.
- Metaphor: Imagine enclosing the glacier in a box where all necessary processes occur internally.
Inputs in Glacier Systems
- Definition: Additions to the glacier’s mass.
- Types of Inputs: Precipitation (e.g., snow), eroded debris from surrounding areas.
Stores in Glacier Systems
- Definition: Mass that glaciers hold.
- Main Component: Primarily ice, also includes sediments and meltwater.
Types of Glacial Stores
- Subglacial: Material found beneath the glacier.
- Englacial: Material contained within the glacier.
- Supraglacial: Material located on the surface of the glacier.
Outputs in Glacier Systems
- Definition: Mass that leaves the glacier.
- Common Forms: Meltwater and calving events at the snout of the glacier.
Flows in Glacier Systems
- Definition: The transfer of mass or energy within glaciers.
- Types of Flows: Includes mass flows from snow and ice movement influenced by gravity.
Glacial Energy
- Source: Gravity causes glaciers to move, yielding kinetic energy.
- Importance: This energy facilitates processes like erosion.
Dynamic Equilibrium
- Definition: A state of balance in glacier mass.
- Condition: Mass gain from inputs equals mass loss from outputs over a specific time.
Equilibrium Line
- Definition: The altitude on a glacier where mass gain equals mass loss.
- Significance: Indicates the stability of glacier mass over time.
Feedback Loops
- Definition: A series of processes where one process triggers another.
Types: - Positive Feedback: Enhances the initial process.
- Negative Feedback: Counteracts the initial process.
Polar Environments - Current Distribution
- Locations: Found at high latitudes within the Arctic and Antarctic Circles.
- Temperature Criteria: Areas maintain an average temperature below 10°C in the warmest month.
Ice Sheet Extent
- Maximal Extent: Ice sheets reach their greatest size during the coldest winter months.
- Arctic and Antarctic Winters: Occur from December to March (Arctic) and March to October (Antarctic).
Climate in Polar Environments
- Characteristics: Consistently below freezing temperatures and minimal rainfall.
- Impact on Ecosystem: Slow nutrient cycles lead to nutrient-deprived soils.
Precipitation in Polar Areas
- Average Rainfall: Typically does not exceed 100mm per year.
- Winter Temperatures: Can dip as low as -40°C in some regions.
Glacial Climate Impact
- Glacial Advance: Historical advances and retreats correspond to global climatic changes.
- Current Trend: Majority of glaciers are retreating due to rising global temperatures.
Historical Climate Events
- Last Glacial Maximum: Period marked by significantly cold global temperatures.
- Little Ice Age: Brief global cooling from approximately 1300 to 1870.
Glacial Behavior During Little Ice Age
Observation: Glaciers in the Alps advanced significantly during this period due to heavy snowfall.
Types of Glaciers
Warm-Based Glaciers:
- Environment: Often found in alpine climates with fluctuating temperatures.
- Characteristics: High erosion, significant meltwater production.
Cold-Based Glaciers
- Definition: Glaciers that exist at lower temperatures.
- Characteristics: Less melting and slower movement due to lower temperatures.
Pressure Melting Point (PMP)
- Concept: The temperature at which ice melts under pressure.
- Effects: Increased pressure leads to lower melting temperatures than 0°C.
Glaciated Landscapes Formation
- Processes Involved: Shaped by geomorphological, periglacial, and fluvioglacial activities.
Types of Erosion Processes
- Plucking: Ice pulls rocks from bedrock, resulting in a jagged surface.
- Abrasion: Embedded rocks scratch the bedrock, creating a smooth surface with striations.
Frost Action
Definition: Weathering process where water enters rock cracks, freezes, and expands, causing fractures.
Nivation
A type of weathering related to snow and ice, leading to erosion and the formation of hollows.
Ice Movement in Glaciers
Mechanism: Glaciers move under their own weight, primarily driven by gravity.
Internal Deformation
Movement of ice layers due to pressure, causing some layers to flow faster than others.
Compressional Flow
Occurs when ice encounters shallower gradients, leading to compression and thickening.
Extensional Flow
Definition: Ice accelerates as it moves over steep gradients, causing thinning and crevasse formation.
Rotational Slip
Definition: Movement where trapped ice in hollows continues to flow downwards, aided by meltwater.
Basal Sliding
The process of a glacier sliding over bedrock, enhanced by meltwater acting as a lubricant.
Influencing Factors on Glacier Movement
- Composition of Glacier: Determines the rate and nature of glacier movement and erosion.
- Landscape: Steeper terrain increases gravity’s effect and can accelerate glacier flow.
Relief Impact on Glaciers
- Definition: Relief refers to the terrain’s steepness affecting glacier dynamics.
- Effect on Movement: Steeper relief enhances gravitational forces acting on glaciers.
Periglacial Processes - Active Layer
Definition: The upper layer of permafrost that thaws during summer months, influencing surface processes.
Frost Heave
Definition: Process where freezing water expands beneath rocks, pushing soil and rocks upwards.
Solifluction
Definition: The slow mass movement of waterlogged soil, influenced by gravity, especially on slopes.
Environmental Fragility
Definition: A characteristic of ecosystems vulnerable to damage due to their inability to adapt.
Ecosystem Resilience
Importance: Resilience is crucial for surviving climate changes and human impacts.
