The characteristics of extreme environments
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What is an extreme environment?
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All Flashcards in Topic 9.1
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9.1.112 cards
What is an extreme environment?
A place whose **harsh physical conditions** make life and human activity very difficult (e.g. hot deserts).
Define a hot desert (rainfall).
A hot, **arid** environment receiving **under ~250 mm** of rain a year, with far more evaporation than rainfall.
Define a semi-arid environment.
The drier **margins** of deserts, ~**250-500 mm** of rain a year, sparse grass/scrub and prone to drought.
What is aridity?
A **permanent water deficit** - potential evaporation exceeds rainfall, so water is always scarce.
What is the diurnal temperature range in deserts?
The **large gap** between hot days and cold nights - clear skies and bare ground lose heat fast at night.
Sub-tropical high pressure - why does it dry deserts?
Air that rose at the equator **sinks** at ~20-30 degrees; sinking air **warms and dries**, so rain cannot form.
Rain shadow - how does it cause aridity?
Mountains force air to rise and drop rain on the windward side, leaving the **leeward side dry** (e.g. the Atacama behind the Andes).
Cold ocean current - effect on rainfall?
It **chills the air**, so little moisture evaporates onto the land - keeping coasts like the Atacama and Namib arid.
What is continentality?
Being **far from the sea**, so moist air rarely reaches the interior (e.g. the Gobi, central Australia).
Two named hot deserts and what dries each?
**Sahara** - sub-tropical high pressure + continentality; **Atacama** - rain shadow of the Andes + a cold current.
Why is the Sahel an extreme environment?
Its rainfall is **low, seasonal and unreliable**, bringing **drought, flash flooding and water scarcity**.
Name one response to desert water scarcity.
**Desalination** - removing salt from seawater (e.g. Saudi Arabia, the UAE), where there are almost no rivers.
9.1.212 cards
Define the cryosphere.
All the **frozen water** on Earth — ice sheets, glaciers, sea ice and permafrost.
Glacial vs periglacial environment?
**Glacial** = under ice now (ice sheets, mountain glaciers); **periglacial** = frozen ground (permafrost), not under ice.
Define permafrost.
Ground that stays **frozen for two or more years**; it defines periglacial cold environments.
What is the active layer?
The surface layer above permafrost that **thaws in summer** and refreezes in winter.
Define an ice sheet.
A **continental-scale glacier** — today only Antarctica and Greenland.
What is a corrie (cirque)?
An **armchair-shaped hollow** high on a mountain where a glacier first formed.
Where are cold environments found?
At **high latitudes** (Arctic, Antarctica) and **high altitudes** (mountain glaciers, even near the Equator).
Why does some permafrost stay frozen?
Where it is **coldest** — high latitude/altitude, a continental interior, insulating soil, or a north-facing slope.
How do you describe a distribution on a map?
By **latitude and compass direction** (coastal, southern half, inland) — never longitude alone.
Why are polar regions hostile to people?
**Extreme cold, darkness, permafrost, remoteness and ice** limit settlement, farming, transport and building.
Which sector lost the most ice, 1994-2017?
**Arctic sea ice** (~31% of the ~28 trillion tonnes lost); mountain glaciers ~21%.
What does a full Explain [6] on polar hardship need?
**Two** factors, each **developed** to a human consequence — marked 3 + 3, so naming alone is not enough.
Topic 9.1 study notes
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