Download EOLIAN PROCESSES

EOLIAN PROCESSES
(DESERTS AND WIND ACTION)
Desert - an area where the average annual precipitation is < 25 cm/yr (10 in/yr). Deserts (arid)
& steppe (semi-arid) regions cover about 48 million km2, 30% of Earth’s land surface.
Causes of Deserts
1) Horse Latitudes - located about 30°N & 30°S, Tropics of Cancer & Capricorn
(ex: most of the world’s deserts).
2) Rain Shadows - as moist air is forced up over a mountain range, it expands & cools &
loses moisture. On the other side, the dry air compresses & warms bringing high
evaporation (ex: east of the Sierra Nevadas).
3) Distance from Ocean - are deep in the interiors of large land masses far removed from
the oceans (ex: Gobi Desert)
4) Cold Coastal Ocean Currents - cold maritime air warms up as it moves over land
causing high evaporation (ex: Namib Desert of southwest Africa).
5) North & South Poles - caused by the cold descending air.
Deserts have been expanding due to desertification - the conversion of productive rangeland
into desert through a combination of overgrazing & prolonged drought.
Types of Deserts
1) Cold Deserts - with cold winters & hot summers (ex: Oregon, Utah, Nevada)
2) Warm Deserts - with warm or hot temperatures year round (ex: Arizona, New Mexico,
California, Texas, northern Mexico, Africa, Saudi Arabia)