Mass balance Flashcards
What is accumulation?
- Inputs into a glacial system including;
- Direct snowfall, precipitation, meltwater, rock fragments, avalanches, solar energy (although most of this is reflected)
What is ablation?
- Outputs from a glacial system including;
- Meltwater in warmer months, sublimation and evaporation, eroded material in meltwater, calving, solar energy reflected
What is the albedo effect
The albedo effect is where energy is reflected off surfaces. Light coloured surfaces return a large amount of sun rays, whereas darker surfaces absorb them.
What is the glacial budget?
- When accumulation>ablation, the snout of the glacier advances as it gains mass
- When ablation>accumlation, the snout of the glacier retreats as mass is lost
- When accumulation=ablation, the snout of the glacier remains stationary
What is the equilibrium line on a mass balance graph?
Is shown when the amount of accumulation=ablation, also know as the firn line
What are the spatial variations in a glacial budget?
- Most accumulation occurs at the upper end of a glacier because at higher altitudes it is colder. There is net accumulation in this area so can be called the accumulation area
- Most ablation occurs at the lower end of a glacier because at lower altitudes it is warmer. There is net ablation on this area so can be called the ablation area.
What are temporal variations?
The mass balance changes seasonly.
- In winter months there is a net accumulation in the glacial budget
- In summer months there is a net ablation in the glacial budget
What is a positive feedback loop within a glacial system?
Lowering of temperature - increased snowfall - increase the albedo of the ice surface - contributing to further cooling and more accumulation.
What is a negative feedback loop within a glacial system?
Higher temperatures - increase evaporation precipitation (snowfall) - snow accumulation balances the losses from ablation at higher temperatures.
