CAIE Geography Pre-U - 1A: Hot Arid and Semi-Arid Environments

Flashcards based on lecture notes for exam preparation.

What is the definition of ?

Lack of moisture, insufficient rainfall for most trees or woody plants, extremely dry with low precipitation and high evapotranspiration rates.

The _ is calculated by dividing average annual precipitation by annual potential evapotranspiration.

Average annual precipitation divided by annual potential evapotranspiration.

A hyper-arid environment has an aridity index of ___.

Aridity index < 0.05, rarely exceeds 100mm annual precipitation.

The global distribution of arid environments is __.

Mainly on west sides of continents, along the Tropic of Cancer or Capricorn.

__ is the degradation of land in arid and semi-arid regions.

Land degradation in arid and semi-arid regions due to climatic and human factors.

Common causes of desertification include __.

Overfarming, deforestation/removal of plants, overgrazing, climate change, lack of precipitation, natural disasters.

_ are periods of increased rainfall.

Periods of increased rainfall.

Archaeological evidence for past changes in aridity includes __.

Rock paintings showing animals from wetter climates, ancient remains showing water damage.

The rain shadow effect leads to arid conditions because __.

Air rises on windward slopes, cools, and condensation occurs, producing rain. Air descends on leeward sides, warms, and no condensation occurs, leading to arid conditions.

Global atmospheric circulation causes deserts due to __.

Most deserts in subtropical high-pressure zones with subsiding air in the Hadley cell's descending limb, causing dry, stable conditions.

Cold ocean currents cause deserts on western coasts because __.

Deserts on western coasts due to upwelling of cold water reduce air temperature and moisture-holding capacity, resulting in drier conditions.

Typical desert climates are characterized by __.

High diurnal ranges due to low cloud cover at night, leading to high heat loss and cold nights. Low annual temperature ranges depending on latitude.

Rainfall in desert climates is characterized by __.

Low total annual rainfall, often occurring in short periods. All arid/semi-arid areas have < 500mm annual precipitation. Extreme rainfall events are common.

_ are underground water sources in permeable rock.

Underground water sources in permeable rock, fractured rock, or unconsolidated particles.

Coastal mist and fog are formed by __.

Sinking air above moist air formed over the sea creates mist/fog traveling over land.

__ are water droplets on exposed, thin objects due to condensation.

Water droplets on exposed, thin objects in the evening/morning due to condensation.

_ is the breaking down of rock.

Breaking down of rock leading to decomposition, degradation, and sediment production.

The process of frost shattering involves __.

Water penetrates cracks, freezes at night, expands, and puts pressure on cracks. Ice melts during the day, traveling further into cracks. Repeats until rock breaks.

Thermal fracture occurs because __.

Rocks expand during hot days and contract during cold nights, creating stress. Outer layer flakes off.

Salt weathering occurs when __.

High temperatures draw saline groundwater to the surface. Evaporation leaves salt crystals that grow and stress joints/pores, causing disintegration.

Deflation by wind involves __.

Loose, fine regolith (unconsolidated material) removed by the wind.

Abrasion/Corrasion by wind involves __.

Wind-borne particles driven against rocks act like sandpaper.

In wind transportation, suspension involves __.

Particles < 0.15mm (silt or clay) carried in the air.

In wind transportation, saltation involves __.

Particles between 0.15mm and 0.25mm move in small leaps.

In wind transportation, surface creep involves __.

Particles > 0.25mm rolled/pushed along the ground.

Deflation hollows are __.

Large, enclosed surface depressions created by wind removal of loose particles, collect runoff, and form salt lakes.

Ventifacts are __.

Cobbles/pebbles shaped by sand carried in the wind, having smooth sides separated by sharp edges.

Yardangs are __.

Streamlined, steep-crested, linear ridges of clay, rock, or silt caused by abrasion and small deflation.

Wadis are __.

Dry river beds forming temporary channels after rain; steep sides and wide floor formed by flash floods.

Mesas are __.

Elevated flat-topped land areas with steep sides formed by tectonically uplifted horizontally layered rock undergoing differential erosion.

Dunes are formed by __.

Formed by deposition of fine materials when wind speed decreases around vegetation, rocks, or other obstacles.

Barchan dunes are __.

Small crescent-shaped dunes pointing downwind, formed by dominant wind direction and limited sand supply; highly mobile.

Seif dunes are __.

Large dunes developed from barchan dunes due to elongation caused by constant switching in prevailing wind direction.

Star dunes are __.

Pyramidal-shaped, tall dunes formed by strong winds from multiple directions.

Draa dunes are __.

Sequence of large star dunes forming a ridge.

Alluvial fans are formed when __.

Formed when water carrying sediment reaches a plain/basin, slowing down, spreading out, and depositing sediment.

Playas are __.

Salt lakes occupying shallow, ephemeral saline depressions with no surface outlet.

Salt flats are __.

Flat expanses encrusted with salt crystals and minerals, formed when water from a salt lake evaporates.

Washes are __.

Drainage areas in desert terrains, dry beds of sandy soil allowing water to penetrate back into aquifers.

Overgrazing contributes to desertification by __.

Removes native vegetation, compacts soil, and increases surface runoff.

Climate change contributes to desertification by __.

Increases temperatures, evaporation, and erosion; shifts food production areas.

Deserts present both opportunities and constraints, including __.

Climate: Continuous growing season due to sunshine but low water. Alluvium Deposits: Nutrient-rich fine soils that warm quickly but prone to wind erosion and flash floods.

Contour bunds are used to __.

Slow water flow to increase infiltration and prevent mineral wash-off.

The Zai Technique involves __.

Digging pits filled with organic matter to trap water and nutrients, increasing soil stability and fertility.

Planting trees helps manage desertification by __.

Reduces soil erosion and increases biodiversity.

Tourism has both benefits and drawbacks, including __.

Economic benefit and infrastructure improvement, but environments are fragile, have low carrying capacity, and are vulnerable to human activity.