GCSE Deserts OCR A

Extreme environments

Definition- A place that presenrs challenges that make it difficult for people and animals to survive there. Eg extreme temp, lack of water, altitude etc

Reactions to extreme environments

1) People enjoy beauty

2) Wear specialist clothes

Characteristics

·       Little vegetation

·       Remote location

·       Harsh climate

·       Difficult terrain

Deserts

·       Less than 250mm/year

·       High diurnal temp range ↑ 50:

·       Due to prevailing wind blowing hot air over, sun overhead all year, no cooling sea near

·       Night temp to ↓ 0:

·       No cloud to trap heat:

·       No clouds as high pressure

·       Moisture lost as wind travels further in ∴ no clouds

Desert Uses

·       Energy- Solar, as well as oil= naturally occuring

·       Tourism- Nice weather, sand surfing + Ghawar is an oilfield in Saudi Arabia. It is the worlds biggest oilfield in the world and produces 5.5% of the worlds global oil. 

·       Eco tourism- Nomadic tribes

Location

Between 30* north/south of equator.

Processes:

Exfoliation: Occurs in hot, dry climates. The outer layer of the rock is heated by the sun during the day, causing it to expand, during the night, as the temperature drops, the rock contracts. This constant expanding and contracting eventually leads to the outer layers of the rock pealing away, leaving behind them rounded rocks and dome shaped outcrops.

Freeze thaw :Occurs in areas where the temperature regularly drops below 0°C.Water enters cracks in the rock during the day. Overnight the temperature drops and the water freezes. As it freezes, it expands.The expanded ice places pressure on the rocks around it.Over time this constant pressuring of the rock causes it to crack and split.

Crystalisation If water entering the pore spaces or joints in rocks is slightly saline then, as it evaporates, salt crystals are likely to form. As the crystals become larger, they exert stresses upon the rock, causing it to disintegrate. This process occurs in deserts and coastal areas (areas contains sodium sulphates, magnesium sulphates and calcium chloride) where capillary action draws water to the surface and…