glacial systems Flashcards
what is accumulation?
• the input of snow and ice to a glacier
what factors increases accumulation?
• wind deposition
• avalanches
• precipitation
what’s ablation?
• the output of snow and ice from a glacier
what increases ablation?
• melting
• sublimation
• evaporation
• calving
• high temperatures
what are some reasons for the variation in the rates of accumulation?
• Areas with more precipitation, ie snow, will experience higher accumulation rates.
• Windward slopes tend to receive more snow due to orographic lift, and leeward slopes may receive less.
• high altitudes generally receive more snowfall due to relief rainfall and have lower temperatures, which can increase accumulation rates.
• Areas with more vegetation can trap snow, so more accumulation
• winter seasons bring more precipitation and colder temperatures .
what impact does variation in accumulation and ablation have on the glacier mass balance?
• When accumulation is greater than ablation, the glacier gains mass. usually occurs in colder climates
• when ablation is greater than accumulation, the glacier loses mass and usually happens in warmer conditions
• a glacier is in equilibrium when accumulation equals ablation
what is glacial mass balance?
how do you calculate it?
• the overall growth or decline in the mass of a glacier
• calculated by subtracting the total annual ablation from the total annual ablation
what is a positive feedback loop?
state and explain two examples
• a process where an initial change leads to further changes in a negative direction
• ice melts due to rising temperatures, reducing the Earth’s albedo, so more sunlight is absorbed by darker areas causing more warming and leading to even more ice melting.
• permafrost melts due to rising temperatures, releasing trapped methane, (a GHG). which contributes to further warming, leading to even more permafrost melting.
VICIOUS CYCLE
what is a negative feedback loop?
state and explain two examples
• when a change occurs, a negative feedback loop works to bring the system back to its original state (positive direction)
• As glaciers melt, they expose darker land below it, absorbing more sunlight. if the climate cools after a period of warming, the exposed areas can refreeze or accumulate new snow, increasing the albedo effect which helps to cool the area and slow down further melting.
• a glacier melts creating meltwater pools on its surface. If they become big enough, they can insulate the glacier from the air above, reducing the rate of melting, temporarily stabilising the glacier
** they may not be strong enough to counteract the long-term trends of global warming.
what’s calving?
how does it affect a glacier?
• the process where chunks of ice break off from the edge of a glacier into the water, creating icebergs.
• it contributes to mass loss of the glacier (ablation) and can accelerate melting.
what’s sublimation?
how does it affect glaciers?
• when a solid turns directly into a gas, bypassing the liquid state
• results in ablation of a glacier
how does evaporation result in ablation?
• When the temperature rises, the heat causes water molecules transition from a liquid state to a vapor state, reducing mass of the glacier.
how does melting result in ablation?
• When temperatures rise, the surface of the glacier begins to melt, creating meltwater. which flows off the glacier, reducing its overall mass.
what is the accumulation zone?
• the zone at the upper part of the glacier where net accumulation is greater then net ablation
what is the ablation zone?
• the lower part of a glacier where net ablation is greater then net accumulation
