Glacier- Formation

Question 1

What is glacier formaiton dependent on?

Answer 1

Balance of input/output

Question 2

What is temperature change dependen on?

Answer 2

Specific heat capacity

Question 3

Specific heat capacity for ice is?

Answer 3

1.751J at -50C or 2J at -10C

Question 4

Specific heat capacity for H2O?

Answer 4

4.127J at 0C.

Question 5

Which state changes release energy?

Answer 5

Evporation and freezing

Question 6

Watts

Answer 6

Equal to one joule per second, measured against surface area per square metre

Question 7

What is energy flow of a glacier compose dof?

Answer 7

Incident Solar Radiation
Reflected Infrared Radiation
Letent Heat transfer by condensation
Latent Heat consumed or released during melting and freezing

Question 8

Why does TOA atmospheric radiation decrease with altitude?

Answer 8

Diffusion and filtration.

Question 9

Optical Depth

Answer 9

This is an extinction coefficienct of an atmospheric layer inegrating distance, humidity, cloudiness and concnetration of other particles.

Question 10

What does incidient SW radiaiton depend on with declination?

Answer 10

Latitude, slope gradient and time of day.

Question 11

What is an example of influence of clouds on energy balance?

Answer 11

Where clear air, SW up to 1200Wm-2, whilst cloudiness reduced to few percent

Question 12

What is the equation of radiant flux?

Answer 12

Emissivity multiplied by SB constant multiplied by temperature^4

Question 13

What does sensible heat depend on?

Answer 13

Gradient between atmosphere and glacier, transfer of molecular momentum

Question 14

What does the atmosphere-glacier gradient depend on?

Answer 14

Turbulence and convectionf of boundary level air

Question 15

What is glacial energy most variable with?

Answer 15

Higher temperatures, strong winds and rougher surfaces.

Question 16

Why are glaciers blue?

Answer 16

Perferential ABSORPTION of blue light

Question 17

Why is ice temperature variable?

Answer 17

Because its meltin point varies with temperature, decreasing with increasing pressure.

Question 18

What is the melting point of the base of a glacier?

Answer 18

at -1.27C if 2000m thick about 17.6MPa

Question 19

What is ice temperature regulated by?

Answer 19

Atmospheric surface energy exchange, geothermal heat flux at bed, frictional heat at bed by sliding.

Question 20

Why might glacial temperature rise occur in winter?

Answer 20

Refreeze of meltwater with released energy.

Question 21

How may snow reduce conductivity?

Answer 21

Air bubbles with less conductive ability.

Question 22

How is geothermal heat flux generated?

Answer 22

Radioactive decay, increasing basal ice temperature

Question 23

How is frictional heat on ice generated?

Answer 23

Sliding at the base

Question 24

What does dT/dt equal?

Answer 24

Shear stress x shear strain rate divided by ice density x specific heat capacity of the ice

Question 25

Basal Sliding

Answer 25

This is the act of a glacier sliding over the bed due to meltwater under the ice acting as a lubricant

Question 26

What are the three types of glacial structure?

Answer 26

Temperate Cold Polythermal

Question 27

Temperate Glaciers

Answer 27

Where melting point is everywhere except a surface layer a few metres thick, due to seasonal temperatures.

Question 28

Where do temperatre glaciers exist?

Answer 28

Where winter snowfall and summer melt is highest, as snow insulates ice from low winter temperatures.

Question 29

Cold Glaciers

Answer 29

These are everywhere below melting point, thus frozen to their beds.

Question 30

Polythermal Glaciers

Answer 30

These are composed of both cold and warm ice

Question 31

Orographic Lift

Answer 31

This occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain

Question 32

What is the most prominent source of accumulation?

Answer 32

Snow precipitaiton, but also supercooled water carreid from winds.

Question 33

How does ice formation occur?

Answer 33

Compaction of multitude of layers, filling air-pores and increasing bulk density.

Question 34

H2O differential densities per cubic metre?

Answer 34

40-200kg for snow, 830-910 fir ice and 1000kg for liquid water at 0c

Question 35

What is requried for firn-ice transformation?

Answer 35

Density increase, filling of air pores, compacting bubbles, pressure.

Question 36

How does compression form ice?

Answer 36

Restructuring of crystals

Question 37

How do melt and refreeze increase copaction rate?

Answer 37

Water percolation into pores of the snow force air outwards, and frezing.

Question 38

Dynamic Recrystallization

Answer 38

This involves nucleation of new dislocation-free grains followed preventing propogation of cracks.

Question 39

What causes reduction in glaciers?

Answer 39

Melting, evaporation, sublimation, wind scouring, iceberg calving