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WIND AND DESERTS • Deserts 1. characterized by a lack of precipitation and high evaporation rates

WIND AND DESERTS • Deserts 1. characterized by a lack of precipitation and high evaporation rates i. rainfall is unpredictable ii. when rain does fall, it is intense and of short duration iii. type of weathering (physical or chemical) iv. importance of running water and wind.

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WIND AND DESERTS • Deserts 1. characterized by a lack of precipitation and high evaporation rates

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  1. WIND AND DESERTS • • Deserts • 1. characterized by a lack of precipitation and high evaporation rates • i. rainfall is unpredictable • ii. when rain does fall, it is intense and of short duration • iii. type of weathering (physical or chemical) • iv. importance of running water and wind

  2. Winds are driven by differential heating of the Earths Surface

  3. • Deserts • 2. location is determined by patterns of atmospheric circulation • i. Coriolis Force • ii. trade winds • iii. horse latitudes • iv. westerlies • v. easterlies

  4. • Deserts 3. types of deserts i. Subtropical (10°- 30°N & S latitude) (1) Sahara ii. Continental Interior (1) Gobi Desert iii. Rainshadow deserts (1) Mohabbi desert

  5. • How Does Wind Carries it Load? 1. bedload i. saltation 2. Suspended load

  6. • Wind Erosion • 1. Deflation - removal of loose material by wind • i. deflation basin-blowout • ii. lag deposits • 2. Abrasion - near surface effect caused by impact of saltating sand grains • i. ventifact (sand blasting)

  7. • Deposition of Material by Wind 1. sand dunes

  8. • Deposition of Material by Wind 1. sand dunes i. types (1) barchan (a) crescent shaped (b) tips point downwind (c) in areas that are flat and dry (d) little vegetation (e) limited supply of sand (f) constant wind direction

  9. 1. sand dunes • i. types • (2) parabolic • (a) crescent shaped • (b) tips point upwind • (c) commonly in coastal areas with strong onshore winds • (d) abundant sand • (e) partial cover of vegetation

  10. 1. sand dunes i. types (3) longitudinal (seif dunes) (a) long, parallel ridges (b) aligned parallel to the wind direction (c) winds generally converge from slightly different directions (d) 30 - 100 m high; 100 km long

  11. 1. sand dunes i. types (4) transverse (a) long ridges (b) perpendicular to the wind direction (c) sand seas (d) 200 m high; 3 km wide

  12. • Deposition of Material by Wind 2. Loess - wind deposited silt and clay

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