DESERTSDESERTS Geography concept analysis

*Agnieszka * Denise * Teshome * Thore*

Ambiguities and Modes of ClassificationAmbiguities and Modes of Classification

desert != dry land : e.g. • volcano deserts • dry/hot deserts• ice deserts• salt desert

2Geographic concept analysis - deserts

• deserted = uninhabited places; the term does not describe the lack of water (arid place) and deserts may be quite heavily populated

• in military terminology, desertion is the abandonment of a "duty" or post without permission from one's Government or superior.

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Ambiguities and Modes of ClassificationAmbiguities and Modes of Classification

Relevant Objective PrimitivesRelevant Objective Primitives

• windspeed• temperature• precipitation• evapotranspiration

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• vegetation• material (rock, sand,

ice, salt)

• characteristic landforms (dunes)

• human inhibitions

Predication CriteriaPredication Criteria

(a) Individuation : check the relevant objective primitives ( precipitation, evapotranspiration)

(b)Demarcation: sudden change in physical paramters

(c) Identity : one connected place of sand, ice …

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Predication CriteriaPredication Criteria

Example Sahara• typical turning circle desert• cloud free sky• no vegetation• arid• high temperature changes• windy• Ground inversion• animals and plants: Fennec Fox, Rose of Jericho

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Predication CriteriaPredication Criteria

Example : Antarctica• whole continent desert• borders of the continent (floating ice/underlying rock)

• extreme changes over time in the year

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Parameters of variabilityParameters of variability

• temperature is not always high (->ice desert)• the changes of temperature can be huge - daily

amplitudes up to 40°C• for many years no drop of water can fall but in the

following year a huge amount can fall• different continents have different values of

maximum precipitation for land called desert• air in the desert is not always dry - it can have up to

70% humidity

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Parameters of variabilityParameters of variability

• different landforms depending on many factors• in some deserts there are specialized animals• close to sea does not mean humid -> Namib Desert• the cover of the desert can be very different

depending on the type of the desert (snow, sand, stones, rocks, etc.)

• the origin can vary (natural processes as climate changes after glacial period to anthropological reasons like deforestation)

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DefinitionsDefinitions

• average annual precipitation of less than 250 millimeters per year

• more water is lost by evapotranspiration than falls as precipitation

• vegetation cover is sparse to almost nonexistent

• sand, rocky, ice

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DefinitionsDefinitions//CharacteristicsCharacteristics

Axioms Expressing Relations to other Axioms Expressing Relations to other Geographic ConceptsGeographic Concepts

• region(Sahara).• region(Antarctica).• region(Great Salt Lake Desert).

• all x (region(x) & precipitation(x)<250 & precipitation(x)<evapotranspiration(x) -> desert(x)).

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Axioms Expressing Relations to other Axioms Expressing Relations to other Geographic ConceptsGeographic Concepts

• all x (region(x) & hightempdiffsdaynight(x) -> applicableTemperature(x)).

• all x (region(x) & (vegetation(x)=sparse | vegetation(x)=no) -> applicableVegetation(x)).

• all x (region(x) & (material(x)=rock | material(x)=sand | material(x)=ice | material(x)=salt) -> applicableMaterial(x)).

• all x (applicableTemperature(x) & applicableVegetation(x) & applicableMaterial(x) -> mostlikelyDesert(x)).

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Axioms Expressing Relations to other Axioms Expressing Relations to other Geographic ConceptsGeographic Concepts

• all x (region(x) & (desert(x) | mostlikelyDesert(x)) & (material(x)=sand | material=rock) & temperature(x)>20 -> hotDesert(x)).

• all x (region(x) & (desert(x) | mostlikelyDesert(x)) & material(x)=salt -> saltDesert(x)).

• all x (region(x) & (desert(x) | mostlikelyDesert(x)) & temperature(x)<10 -> iceDesert(x)).

• all x (iceDesert(x) -> smaller(x, Antarctica)).• all x (hotDesert(x) -> smaller(x, Sahara)).• all x (saltDesert(x) -> smaller(x, Great Salt Lake Desert)).

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Thank Thank you you for for yyour our attention!attention!

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