1. Dust Bowl

2. Deserts of the World
< 4 inches of annual precipitation

3. Climate Fx 30o latitude: High pressure systems,
sinking air, warm air, no precipitation.
Equator: Heat rises,
spreads north and south
toward the poles. Keeps
equatorial regions from
getting too warm.

4. Rainshadow Desert Rising air: Precipitation forms on windward side
of mountains. On the lee side, air is dry and accelerates,
making it hot and even drier.

5. Weather patterns

6. Tropical Systems
Gulf of Mexico and tropical systems keep the SE USA moist -- no desert.

7. Wash

8. Alluvial Fans

9. Playa Lakes Badwater Pan, Death Valley, CA. 283 ft. below sea level
Dry lake bed, salt
Same area, after storm

10. Canyons, Playas

11. Pictures
Bajada
Alluvial Fans
Braided Stream Network

12. Desert Pavement

13. Desert Pavement

14. Blowout
Wind causes sand to move, leaving behind depression.

15. Formation of Sand Dunes
Sort of like glacial
scouring; gentle slope
on the windward side,
steep, cut slope on the
lee side.

16. Barchan

17. Transverse
Plentiful Sand Supply

18. Transverse Pic

19. Barchanoid
Intermediate Between Barchan & Transverse

20. Longitudinal
Limited Sand Supply

21. Parabolic
Coastal, Onshore Winds, Some Vegetation

22. Parabolic Pic

23. Star

24. Star Pic

25. Great Sand Dunes National Monument

26. Desertification
Desertification is the degradation of land in arid, semi-arid, and dry sub-humid areas. It is caused primarily by human activities and climatic variations. Desertification does not refer to the expansion of existing deserts. It occurs because dryland ecosystems, which cover over one third of the world's land area, are extremely vulnerable to over-exploitation and inappropriate land use. Poverty, political instability, deforestation, overgrazing, and bad irrigation practices can all undermine the land's fertility.

27. Sand dune reactivation

28. Deforestation
Costa Rica

29. Sub-Saharan Africa deforestation and desertification…
combined with drought…
Nigeria loses
120,000 (!!) acres
each year.

30. Projected Sub-Saharan Population