OCR Geography -Hot Deserts – Flashcards
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30 degrees north and south of the equator. (tropic's of Capricorn and cancer)
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where are hot deserts found ?
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-40 degrees (+) in daytime -Cooler at night -less than 250 mm of rain per year -High wind speeds -lack of cloud cover because there is no cloud cover -High pressure
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Describe hot desert climates ?
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what is happening in the atmosphere around us at any moment.
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What is meant by weather ?
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The average weather over several years.
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What is meant by climate ?
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A place that receives less than 250 mm of precipitation per year.
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What is a desert ?
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The trade winds blow from sub-tropical areas with high pressure towards the equator where there is low pressure they are dry winds e.g. Sahara
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What is a trade wind desert ?
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Cold ocean currents near the coast cools the air so I doesn't rise and there is no rain. cold air sometimes causes mist or fog at sea level e.g. Namibia
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What causes coastal deserts ?
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-when wind blows across a mountain range the air loses moisture. -It creates a rain shadow on the leeward side e.g. Atacama
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What causes Rain-shadow deserts ?
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-Monsoon winds are seasonal winds in Asia -South-West monsoons bring rain that falls mostly falls on the Himalayas -North-East monsoons bring dry weather -e.g. Thar
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What causes Monsoon deserts ?
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North Africa
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Where is the Sahara Desert ?
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Central Australia
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Where is the Australian Desert ?
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South West Africa
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Where is the Kalahari Desert ?
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North West of India
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Where is the Thar Desert ?
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North west of south America (Chile )
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Where is the Atacama Desert ?
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West of North America
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where is the Mojave Desert ?
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The difference in temperature between night and day
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what is diurnal range ?
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-Sand dune is a pile of sand that can be 30 meters high. -Semi circle shaped -They have a very steep side and a less steep side -Wave pattern
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What is a sand dune ?
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-Sand moves like a leap frog movement -Moved by the wind near to the ground
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what is saltation ?
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A gully formed by flash floods
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What is a Wadi ? How are they formed ?
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- Narrow steep sided ridge -The troughs are created by less resistant rock being eroded away by wind -The more resistant rock isn't eroded
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What is a Yardang ? How are they formed ?
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-when wind blown sand has eroded away the less resistant rock by abrasion.
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What is a Rock pedestal ? How are they formed ?
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-deep,steep sided valley -Eroded by water
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What is a Canyon ? How are they formed ?
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Dried out salt lake with a crusty salt surface.
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What is a Salt pan ?
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Butte= small isolated ,flat topped mountain formed but freeze thaw weathering scree at bottom Mesa= flat topped mountain with steep sides (lager than butte) wider than is is tall.
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What are mesa's and Butte's ? How are they formed ?
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The disintegration and decay of rocks.
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What is weathering ?
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The warring away of rocks.
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What is Erosion ?
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The laying down of material that has been eroded.
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What is Deposition ?
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The layers of rock.
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what is meant by strata ?
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lose stones
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what is scree?
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A geographical area where organisms,weather and land scape work together. Every factor depends on every other factor either directly or indirectly
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What is an ecosystem?
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They have characteristics which enable them to survive in the desert - e.g. cactus
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What is an Xerophyte ?
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Organisms that complete their life cycles in weeks or months rather than years
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What is an ephemeral ?
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A series of organisms each dependent on the next as a source of food
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What is a food chain ?
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-Drought -Climate getting hotter -Growing population = more food needing to been grown -Deforestation =soil is being blown away
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What are the causes of desertification ?
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-Ground is left very dry -Useless for farming -Less food can be produced -Lack of soil
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What are the consequences of desertification ?
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- Sustainable farming -Stop over grazing to let ground recover -Plant trees to keep soil in place -Irrigate soil so it is wet
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What are the solutions to desertification ?
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-Creates jobs -Improves lives for locals - more money =better housing,education, better food.
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What are benefits of tourism in the desert ?
