Introduction to Glaciers Flashcards
(48 cards)
Glaciers cover how much of the planet?
10%
Arctic, Antarctic and Himilayas
An important source of…
Freshwater supply and water generation
Norway 98% of energy is from HEP- 15% of which comes from glacial catchments.
1 billion people live in the vicinity of the Himalayas- freshwater during the dry season.
The last ice age
Ended around 100 years ago
Covered around 30% of planet
Snowball earth
Entire earth covered in glaciers
Why are glaciers important in energy supply?
If the volume of ice changes so does the power distribution
Where do we find glaciers generally?
High latitude places
High elevation places
E.g Alps, Scandanavia
In order to have a glacier we need…
Snow on a mountain that’s going to survive summer.
Built up over years and snow will form ice.
Meltwater from the Himalayas flows into rivers that how many people rely on?
Over 1 billion people rely on for irrigation, livelihood,
power generation…
What basins are most susceptible to reductions of flow?
The Brahmaputra and Indus basins are most
susceptible to reductions of flow, threatening the food
security of an estimated 60 million people
Glacial hazards
As glaciers retreat…
…Moraines can dam meltwater creating a lake
If these lakes breach then can cause catastrophic floods
How to make a glacier?
Snow falling
As weight increases (compacted) = squeezing out air = ice crystals
What is a positive mass balance?
If a glacier is growing it has a positive mass balance
What is a negative mass balance?
If a glacier is shrinking then it has a negative mass
balance
What is the Equilibrium Line Altitude (ELA)?
Altitude on the glacier where the mass balance is zero is
called the Equilibrium Line Altitude (ELA)
What can be measured by field measurements?
Glacier hydrology
Glacier mass balance
Glacier meteorology
What can be measured by remote sensing?
Glacier surface
Glacier types
Cirque Glacier
– Formed in a cirque (bowl shaped depression)
– Significant accumulation from avalanching
Glacier types
Valley glacier
– Flow from the higher accumulation areas down to lower lying ablation areas
- Creator of fjords
Glacier types
Piedmont glacier
– Occur when steep valley glaciers spill into
relatively flat plains
Glacier types
Ice caps
– Defined either as a domed shaped mass of glacier
ice that does not completely cover the topography
– …OR < 50,000 km2
Glacier types
Ice sheets
– Defined either as a domed shaped mass of glacier
ice that completely covers the topography
– …OR > 50,000 km2
– Currently only Antarctica and Greenland, but paleo
examples exist
Glacier types
Crevasses
– reflect stresses imposed on the glacier by the valley sides
- water can melt its way down and ice can go all the way to the bed
Glacier types
Ogives
“Bands” on the glacier surface
– Light bands reflect the “clean” ice that passed over the ice fall in the winter
– Dark bands reflect the “dirty” ice that passed over the ice fall in the summer
What is clean ice?
Clean ice with almost nothing on it
