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ENVS165 - Theory and Laboratory Experiments in Earth Surfaces Processes > Aeolian Processes > Flashcards

Aeolian Processes Flashcards

1
Q

What is wind as a geomorphological agent?

A

Weathering + Erosion + Transport + Deposition = Denudation

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2
Q

What is wind as a geomorphological agent?

A

Erosion, Transport, Deposition
Erodes rocks and sediment
Transport available sediment
Deposits transported sediment

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3
Q

Examples of hot arid zones

A

Sahara Desert - North Africa
Gobi Desert - East Asia

Antarctica - The entire continent
Patagonian desert - South America

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4
Q

What is the distribution of arid zones linked to?

A

Large atmospheric cells

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5
Q

Why are arid zones linked to large atmospheric cells?

A

Airflow in response to gradients in
- Heat
- Pressure

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6
Q

What is the Coriolis force?

A

An apparent force that acts in moving objects in a rotating reference frame, such as the Earth
Caused by the rotation of the Earth
It deflects the path of moving objects, including wind

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7
Q

What does the wind direct result from?

A

The combined action of the pressure gradient and Coriolis force

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8
Q

What are large-scale climate influences?

A

Hadley cell
Maritime vs. continental
Cold ocean currents

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9
Q

What are seasonal large-scale climate influences?

A
  • ITCZ
  • Monsoons
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10
Q

What are daily large-scale climate influences?

A

Breezes

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11
Q

What are Aeolian processes?

A

Sediment transported by fluid - air can be considered a fluid in this context
Random molecular motion and no fixed shape or volume

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12
Q

The viscosity of air?

A

Lower viscosity 1.8x10-5 Nsm-2

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13
Q

The density of air?

A

Lower density 1.3kg m-3

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14
Q

Does air have efficient sediment transportation?

A

No

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15
Q

What is the viscosity of water?

A

High - 1x10-3 Nsm-2

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16
Q

What is the density of water?

A

1000kg m-3

17
Q

Does water have efficient sediment transport?

A

Yes

18
Q

What is sediment movement a function of?

A

Erosivity and Erodibility
+ complicating factors

19
Q

What is erosivity?

A

A function of gravity
lift and drag components

20
Q

When does sediment transport occur?

A

When the force exceeds a threshold value, commonly determined by the particle size of sediment

21
Q

What is erosivity?

A

Wind field
Contact area/ morphology
Impact from other grains

22
Q

What is sediment movement a function of?

A

Of erosivity and erodibility and complicating factors

23
Q

What is erodibility?

A

The susceptibility to wind erosion
- Particle size of surface sediments
- Plant cover
- Surface crusting
- Soil moisture

24
Q

What are the factors contributing to Aeolian landforms?

A

Wind strength (velocity and time), direction and directional variability (eg seasonal)
- Sediment - source, grain size
- Moisture/ adhesion agent
- Vegetation
- Obstacles/ geomorphology
- Humans

25
Q

Sand sediment size?

A

2 - 0.063mm
or
2000 - 63 um

26
Q

What is the typical wavelength of sand dunes?

A

<1m to several 10s km, h: 10s cm to >150m

27
Q

What are the major regional controls of sand dunes?

A

wind regime and sediment supply

28
Q

What are the different types of sand dunes?

A
  • Transverse dunes
  • Linear Dunes
  • Star dunes
29
Q

What are the most common sand dunes?

A

Linear dunes are most common globally
c. 50% all dunes

30
Q

What are the wavelengths of ripples?

A

<1 cm to c. 25cm, h: <h to c. 5cm
Dimensions controlled by grain size and wind speed

31
Q

What is the size of silt sediment?

A

0.063 - 0.004 mm
or
63 - 4 um

32
Q

Silt landforms

A
  • Loess
33
Q

What is loess?

A

Typically silt size particles but some sand and clay too
Alternating layers if silt and soils

34
Q

What are Yardangs?

A

Bedrock carved by the wind abrasion (dust and sand)

35
Q

What are ventifacts?

A

Rock abraded (and pitted) by wind-driven sand

36
Q

What are pavements?

A

Or lag gravel
- the material left behind as the finer material has been eroded away

37
Q

Why is dust a critical component of Earth Systems?

A
  • Surface-atmosphere feedback, radiation balance & climate modulation
  • Ocean fertilization and CO2 breakdown
  • Long-distance nutrient transport & vegetation fertilization
  • HUman health & land use
    The dust cycle interacts with the ocean’s biological pump and reduces atmospheric CO2 through biological processes

ENVS165 - Theory and Laboratory Experiments in Earth Surfaces Processes (6 decks)

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