climate of arid landscapes
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Climate of Arid Landscapes. What are deserts?. 1. Low & Mid-latitude Deserts 2. Low & Mid-latitude Steppes 3. Applied: Living in the Sahel 4. Desertification. Joshua Tree Desert Preserve. Namib Desert. - PowerPoint PPT PresentationTRANSCRIPT
Climate of Arid Landscapes
1. Low & Mid-latitude Deserts 2. Low & Mid-latitude Steppes3. Applied: Living in the Sahel4. Desertification
Namib Desert
Joshua Tree Desert Preserve
The only deserts in the world that have a reliable source of water are those that
lie alongside a cold ocean current
What are deserts?
Koeppen KeyB: PE > PW: P < ½ PEh: MAT >64º FK: MAT < 64º F
B climates are clearly the most extensive climate over land
(35%)
Map of Arid Lands
Consider: Can h deserts receive > precip than k deserts and still be drier?
General Characteristics of BW 1. Between 15º & 30º N/S Subtropical H predominate2. West coast strong E subsidence
Exceptions to general Characteristics
1. Great Basin/Patagonia (40º)
Rain Shadow
2. Taklamakan/Turkestan/Gobi
moisture-bearing air mass
3. N. East Africa & Somalia
Asia excludes maritime air
highlands & S. Asian monsoonH
L Summer
Great Basin
Taklamakan
Weak (E) /strong (W) subsidence
Applied Regional Climatology: Living in the Sahel
Human response to heat1. The human thermostat2. Dehydration (15-20% of body wt.)
The Sahel is a region of & in transition (BSh)
When over 100,000 people in the Sahel died , the human consequences of climate change became a reality.
3. Adaptation Acclimatization
- low body mass, long limbs,
long nose(humidify air)
- > in blood and sweat, < heat rate
Loose cloths on a Tuareg, Algeria
Animal adaptation, Thorny Devil
Is the Sahel Experiencing Desertification
Advancing Deserts
1. 50 m. ac. of lost productivity/yr (1970’s) or 30 mi/yr
2. Causes of desertification- heavy settlement (>30 million)- drought/southward shift in the ITCZ- overgrazing = > albedo = absorb <
heat = < convection = stay desert- less evapotranspiration- fluctuations in global climate
- rainfall & revegetation- tied to sea surface
temperatures- Sun spot cycle?? No one answer
Basal Zone
Metabolic reserve
Desertification-Climate Feedback
Is the Sahel Experiencing DesertificationThe Many Human Causes of Desertification
Deforestation, fuel gathering in Mali
Ground water removal, Center-
pivot irrigation, Libya
Fossil water removalMore wells = more desertification, Niger
Grazing, especially goats
Agriculture: peanut production & field
abandonment
Barren circles/ year around grazing
Is the Sahel Experiencing Desertification
Center-pivot
Armored soil
Wind erosion
Applied Regional Climatology: Living in the Sahel
Desertification in Decline
Between 1984 and 1991 the area of desert has declined by
270,000 sq mi