Relief & Climate Characteristics (SL IB Geography)

• Around the world, cold environments vary
  • For instance, polar regions are considered to be dry (arid) but some areas can be hyper-arid  
  • At the upper latitudes, the sun does not rise or sink for several months of the year

Polar 

• Climate
  • Harsh, covered in snow and ice
  • Long winters and short summers 
  • Snow storms and cold winds for most of the year
  • The Arctic's mean temperature range is -28 °C to 4 °C
  • Average annual precipitation of approx. 100mm
  • The Antarctic's mean temperature is -55 °C in some places
  • Coastal areas are milder, with an annual average of -10 °C
  • The annual average precipitation is 200 mm
• Relief
  • The Arctic is a frozen ocean mostly surrounded by land
    • It has pack and drift ice
    • Rugged shores
    • Flat coastal plains
    • Rolling hills
    • Mountains surpassing 6 000 m above sea level
    • The Arctic has moderate relief
  • The Antarctic is an area of land surrounded by oceans
    • Covered in a thick ice sheet 
    • The Transantarctic mountain range divides the continent east and west, with peaks above 4 000 m
    • West Antarctica has the highest mountain (Mt Vinson) at 4892m above sea level
    • Antarctica has the highest average surface elevation of all the continents, at around 2000m above sea level
    • The highest elevation is over 4 000 m
    • Therefore, Antarctica has a rugged relief

High-mountain (non-tropical)

• Climate
  • Cool climates with some snow coverage but not all year
  • Seasonal temperatures range from −10 °C in winter to 20 °C in the summer months
  • Precipitation in high mountains depends on aspect
    • Windward sides receive large amounts of precipitation, with snow in the winter months
    • Leeward sides are in the rain shadow and, therefore, drier and protected from strong winds
    • On average, temperatures decrease with elevation at roughly 10 °C per 1000 m, so high mountains will be much colder than lower-altitude environments
• Relief
  • Some mountain environments may have a wide diurnal range
  • Some mountain areas are dry because they are in the rain shadow, while others are wet with high rates of rainfall
  • Mountains may appear as a single feature or in a range
  • They can be formed through folding, such as the Andes, or through volcanic eruptions (Mount Elbrus, Caucasus)
  • They usually have steep slopes, with scree at their bases, alternating between valleys, hills and peaks
  • They can be classified as rugged relief

Glacial

• Climate
  • Characterised by permanently low temperatures, but may rise above 0 °C with seasonal temperature variations 
  • Cold climates in high latitudes and altitudes
  • Ice remains throughout the year
  • High precipitation but limited liquid precipitation provide inputs into the glacial system
  • Little seasonal temperature variation 
• Relief
  • Can be covered in u-shaped valleys along with steep, eroded mountain peaks
  • Or deep valleys with sediment deposits
  • Soil exposure is less due to snow cover
  • If sea invades the deep valley, it becomes a fjord
  • Can be classified as rugged relief

Periglacial

• Climate
  • Cool climates with some snow coverage but not all year
  • Seasonal temperatures range from −10 °C in winter to 20 °C in the summer months
  • Mean average temperature between -1 °C and -3 °C
  • Precipitation in alpine mountains depend on aspect
    • Windward sides receive large amounts of precipitation, with snow in winter months
    • Leeward sides are in the rain shadow and, therefore, drier and protected from strong winds
    • Mean annual precipitation less than 1 000 mm
• Relief
  • Found mainly in the northern hemisphere
  • Lack permanent ice cover, but experience freezing temperatures most of the year
  • Have a layer of permafrost beneath the active soil layer
  • Can be classified as moderate relief with significant elevation changes and a mix of landforms

Climate

• Hot, arid environments share a number of climatic characteristics
• Located in zones of high atmospheric pressure due to sinking, warm, dry air
• Insolation is strong because of a lack of cloud cover and the angle of the sun
• Temperatures are high with large diurnal ranges (up to a 30 °C difference) 
  • The diurnal range is less extreme (up to15°C) in semi-arid regions
    
  • The mean annual temperature of most arid margins is lower by approximately 10 and 20 °C
  • Distance from the coasts: land heats and cools faster inland, providing a greater range of temperature
  • Height above sea level (elevation): the higher the region, the cooler it will be
  • Albedo effects temperatures: salt-encrusted, dried-out lakes reflect insolation, making the area cooler
• Strong desert winds and sandstorms are common
  • Changes in temperatures create steep pressure gradients that generate strong winds
  • Harmattan winds from the Sahara create powerful dust (loess) storms that blow over West Africa between Nov and April 
  • Convection winds are typical late afternoon and evening
• Precipitation is usually small, infrequent but intense, resulting in flash flooding
  
  • The overhead sun (low latitude) provides intense convective activity that triggers thunderstorms
  • Arid regions receive 25–250 mm of precipitation per year
  • Semi-arid areas have seasonal rainfall between 250 and 500 mm per year
  • Areas closer to cool ocean currents have lower temperatures and produce sea fog

Relief

• Deserts are considered active, mobile landscapes
• Vegetation is sparse, such as grassland, with few trees 
  • However, irrigation schemes show that many hot deserts have potentially fertile soils
  • Allowing some areas to be permanently or seasonally inhabited by people
• Surfaces are hard (baked by the Sun) or have exposed rock
  • Making infiltration rates poor and increasing surface runoff
• Relief can be divided into 3 types:
  • Hamada: most of the sand has been removed, leaving behind a landscape of gravel, boulders and bare rock plateaus
  • Reg: hard, impermeable surfaces composed of rock fragments set in sand or clay
  • Erg: sandy deserts/sand seas, common only in about 30% of deserts.  Their distribution appears to be climate-linked (i.e. less than 150 mm of rain)

• Desert landscapes are diverse due to:
  • Geological factors (tectonics and rock type)
  • Climate: temperature, rainfall and wind
  • Weathering and mass movement processes
  • Time