Key Terms

Question 1

Potential evapotranspiration

Answer 1

is the maximum amount of evaporation and transpiration which could occur if water supply was unlimited.

Question 2

Solar radiation

Answer 2

radiation emitted from the sun

Question 3

Conduction

Answer 3

transfer of heat loss r gain through direct contact

Question 4

Convection

Answer 4

transfer of heat through convective movement of air

Question 5

Terrestrial radiation

Answer 5

radiation emitted from the earth

Question 6

Albedo

Answer 6

the percentage of solar radiation reflected, as opposed to absorbed, by the earths surface

Question 7

Trade Winds

Answer 7

surface prevailing winds which blow fro subtropical high pressure cell towards the Equator.

Question 8

Advection fog

Answer 8

fog created when warm moist air comes into contact with a cold surface

Question 9

Inversion layer

Answer 9

air layer where temperature rises rather than falls with height

Question 10

Inter-tropical convergence zone

Answer 10

an area of rising air, low pressure, converging surface Trade Winds and high temperatures coincident with the Equator.

Question 11

Coriolis

Answer 11

deflection of global winds by the rotation of the earth

Question 12

Polar front

Answer 12

boundary about 50 degrees N and S of the Equator where cool air from the poles meets warm air form the subtropical high pressure cells producing rain.

Question 13

Alveoles

Answer 13

small hollows, 5 - 50 cm in size, occurring in clusters or honeycombs with thin partitions strengthened b case hardening.

Question 14

Tafoni

Answer 14

hollows a few metres across with arch shaped entrances, often developed along lines of weaknesses such as joints and bedding planes.

Question 15

Case hardening

Answer 15

a hard layer of salt encrusted rock formed where salts have been drawn to the surface by capillary action

Question 16

pedestal rock

Answer 16

isolated pillar of rock with an indented profile

Question 17

Inselbergs

Answer 17

upstanding masses of crystalline rock that project above plains in deserts and semi-arid areas

Question 18

Hydrolysis

Answer 18

a weathering process where water reacts with minerals such as feldspars to produce clay minerals

Question 19

Deflation

Answer 19

the entrainment and removal by wind of unconsolidated material.

Question 20

Corrasion

Answer 20

when wind-blown sand abrades rock surfaces

Question 21

Deflation hollows

Answer 21

large enclosed depressions partly created by deflation; for example, the Qattara Depression in the Sahara

Question 22

Salt pan

Answer 22

flat areas encrusted with salt sometimes filled with shallow, saline lakes

Question 23

Desert pavement

Answer 23

surface of stones resting on a finer material such as sand, silt or clay. Known as gibber plains in Australia, and stone pavements in USA. Formed where wind or water selectively removes finer material to leave behind larger stones. Alternative theories suggest that coarse material is brought to the surface by cycles of heating and cooling, freezing and thawing, and wetting and drying.

Question 24

Ventifact

Answer 24

wind polished stones which look like brazil nuts and are a few centimeters in size

Question 25

Yardang

Answer 25

linear ridge of clay, silt or rock sculpted by abrasion and deflation

Question 26

Zeugen

Answer 26

a type of pedestal rock with a resistant cap of rock

Question 27

Suspension

Answer 27

fine sediment carried within the air

Question 28

Saltation

Answer 28

movement of sand grains in a series of hops along the ground

Question 29

Surface creep

Answer 29

rolling or pushing of sediment along the gorund

Question 30

Sand sea

Answer 30

extensive area of sand containing a variety of dune types

Question 31

Sand dune

Answer 31

Mound of loose, sand-sized material created by grain on grain movement.

Question 32

Sand sheet

Answer 32

Extensive flat or gently undulating area of sand with no significant dunes and sparse vegetation.

Question 33

Ephemeral river

Answer 33

Temporary river which flows intermittently or seasonally.

Question 34

Braiding

Answer 34

The tendency for a river to spit into smaller channels and deposit material when attempting to carry a heavy load.

Question 35

Exogenous river

Answer 35

A permanent river which drives its water from beyond the desert margin.

Question 36

Pediment

Answer 36

Gently sloping bedrock surface extending from a mountain front to the alluvial plain below. Origin controversial, could be formed by wind or water erosion.

Question 37

Ecosystems

Answer 37

Groups of organisms (plants, animals and bacteria) which interact with one another and the environment so that material is exchanged between the living and non-living (air, soil, water) parts of the system.

Question 38

Ephemerals

Answer 38

Plants with a short life cycle which flower after rain and then seed and die.

Question 39

Succulents

Answer 39

Plants which store water in fleshy stems and leaves.

Question 40

Transpiration

Answer 40

Loss of water vapour to the atmosphere mainly via plant stomata.

Question 41

Stomata

Answer 41

Pores in leaves and sometimes stems from which vapour escapes and through which oxygen and carbon dioxide is exchanged.

Question 42

Cuticle

Answer 42

Waxy layer covering the outer plant wall designed to reduce water loss.

Question 43

Xerophyte

Answer 43

Pants living in dry areas which have special mechanisms to survive drought such as swollen stems, thick cuticles, sunken and sometimes closed stomata, small leaves and spines. They include cacti and shrubs such as the creosote bush.

Question 44

CAM (crassulacean acid metabolism)

Answer 44

A process by which carbon dioxide taken in at night is stored until the day when photosynthesis can occur without the plant opening the stomata.

Question 45

Phreatophytes

Answer 45

Plants living in dry areas who have root systems to groundwater supplies.

Question 46

Halophyte

Answer 46

Plant adapted to growing in saline conditions such as salt marshes and salt pans.

Question 47

Cyptobiotic soil crust

Answer 47

Grey-brown soil crust composed of cyanobacteria, lichen moss and micro fungi. Filaments of cyanobacteria bind soil particles.

Question 48

Nomadism

Answer 48

A wandering form if existence in search of good pasture and water for livestock and the collection of fruit and roots.

Question 49

Hydroponics

Answer 49

The growing of crops without soil.

Question 50

Sahel

Answer 50

A semi-arid area in the sub-Saharan Africa stretching from Senegal to Ethiopia where rainfall is unreliable and droughts occur.

Question 51

Desertification

Answer 51

The conversion or marginal land to a desert brought about by naturally occurring periods of drought together with human mismanagement of land.

Question 52

Salinisation

Answer 52

The accumulation of salt in the soil.