hot arid and semi arid environments definitions Flashcards

1
Q

semi-arid

A

having rainfall of less than 500mm per annum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Aridity

A

is a permanent water deficit: less than 125mm of rainfall per annum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

subtropical high-pressure belt

A

a zone of dry, descending air (high pressure) at the poleward side of the Hadley cell, leading to arid conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

subtropical high-pressure belt

A

a zone of dry, descending air (high pressure) at the poleward side of the Hadley cell, leading to arid conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

continentality

A

a climate that is charecteristic of a continental area having very hot summers, very cold winters and low rainfall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Rain shadow effects

A

the drier conditions on the leeward side of the mountains compared with the windward side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

desertification

A

the spread of desert-like conditions, causing land degradation in humid and semi-arid areas - involves the loss of biological and economic productivity and it occurs where climatic variability (especially rainfall) coincides with unsustainable human activities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

diurnal

A

difference between night and day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

salt crystal growth

A

type of mechanical weathering in areas where temperatures fluctuate around 26-28 degrees - leads to the expansion of crystals by 300% such as sodium sulphate and carbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

thermal fracturing

A

form of mechanical weathering caused by repeated cycles of heating and cooling over long periods of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

disintergration

A

type of weathering found in hot desert areas where there is a large diurnal temperature change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

block disintergration

A

form of mechanical weathering whereby rocks are split into blocks, caused by repeated cycles of heating and cooling over long periods of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

granular disintegration

A

form of mechanical weathering whereby different minerals are broken down, caused by repeated cycles of heating and cooling over long periods of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

hydration

A

a form of chemical and mechanical weathering whereby rocks take in water, expand and contract and over time are broken down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

deflation

A

lowering of the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

suspension

A

describes sediment that are carried aloft (in the air) without touching the ground

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

pluvial

A

a period of increased rainfall in deserts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Gours

A

mushroom pinnacles where the base has been undercut, and bands of hard and soft rock have been differentially sand blasted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Zeugens

A

wind-eroded rocks in which different different rock strata lie horizontally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Yardangs

A

wind-eroded rocks where hard and soft rock lie side by side. the softer rocks are worn down to form troughs while harder rocks stand up as wind-worn ridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

barchan dunes

A

crescent-shaped and found in areas where sand is limited but there is a constant wind supply

22
Q

parabolic dunes

A

crescent-shaped dunes that point downwind

23
Q

linear dunes

A

found in areas where there is a seasonal change in wind direction

24
Q

hydrological regime

A

describes annual and seasonal variations in the flow of water in a river

25
flash floods
sudden floods caused by heavy downpours or storms
26
sheet floods
fllods in which the river is not confined in an identifiable river channel, but floods over a large surface
27
exogenous rivers
flow in arid regions but have their origin in humid areas
28
endoreic rivers
flow into inland lakes
29
ephemeral rivers
flow only after rainstorms
30
wadis
generally steep-sided, flat-bottomed river valleys that vary in size from a few metres in length to over a 100km long
31
Alluvial fan
a cone of sediment occuring between a mountain and a lowland plain
32
piedmont zone
is a lowland area/plain generally located at the base of the mountain
33
bajada
is formed by a number of alluvial fans merging
34
pediments
gently sloping areas (<7 degrees) of bare rock where there is a distinct break with the mountain region
35
playas
comprised of a thick crust of salt which has formed after water has flowed into a depression and then evaporated, leaving behind a crust
36
mesas
plateau-like features with steep sides at their edges
37
buttes
smaller versions of mesas. they are thinner landforms that have very steep sides and a flat top
38
inselbergs
any isolated hills that stand prominently over a level surface
39
biomass productivity
the amount of new organic matter produced each year by the existing biomass
40
biodiversity
the range of habitat, species and population variety
41
physical drought
describes water shortages over a long period of time
42
physiological drought
describes water shortages experienced by plants despite there being sufficient soil moisture available - mainly caused by high evapotranspiration rates
43
succulents
plants that have well developed storage tissues
44
Aridisols
desert soils with a low organic content
45
Solonchaks
soils with a saline horizon of NaCl (sodium chloride) - also known as white alkali soils
46
Solonetz
soils with a horizon of Na2CO3 (sodium carbonate) - also known as black alkali soils
47
salination
the concentration of saline salts, usually in the upper horizon of the soil. It can be toxic to plants
48
overgrazing
when pastoralists allow too many animals to graze on a fixed area of land
49
overcultivation
where growing of crops exhausts soil nutrients
50
soil degradation
the decline in quantity and quality of soil