Chapter 16: Wind and Deserts Flashcards
Competance
Ability to transport particles, indicated by the size of the largest particle transported
-Is lowest of all agencies of erosion with wind, can only carry sand (bedload, bouncing rolling sliding)
and silt (suspended load, dust)
-Wind deposited sediments are well sorted because of small range of particle sizes
Deflation
Picking up particles
- Blowouts (deflation hollow)
- Desert pavement (a lag deposit)
Abrasion
Grinding
-Ventifact, yardang, sand blasting
Dunes
Sand depositions, most are asymmetrical
- Wind effectiveness
- Sand supply
- Vegetation cover
Windward Side
Upwind, gradual
- surface of sand transport
- ripples (also asymmetric sand deposit)
Leeward Side
Downwind, slip face (steep)
- Sand flows down slip face
- Crossbedding forms
Longitudinal Dunes
Symmetrical, parallel to wind, highly effective wind
Barchan Dunes
U-shaped, horns point downwind, effective wind, limited sand
Transverse Dunes
Perpendicular to wind, very high sand supply
Parabolic Dunes
U-shaped, horns point upwind, substantial vegetation cover
Loess
Dust deposits
Block-fault mountains
Normal faults in arid regions
- Pediments (erosion surface)
- Fans and bajadas (depositional surface)
- Rain shadow
Hadley Cell
Atmospheric Convection, hot air around equator rises, collects moisture, cools down, and lets moisture go
- Equatorial belt of low pressure, cloudiness and rain, under rising limb
- Subtropical belt of high pressure and aridity, under subsiding belt
- Easterly trade wind belt
Other factors to location
- Located onshore from cold ocean surface currents
- Downwind from mountain ranges (rain shadow)
- Middle of large continents (far from oceans, the source of most moisture)
