Relief & Climate Characteristics (DP IB Geography)

Relief & Climate Characteristics of Cold & High-Altitude Environments

• 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

Relief & Climate Characteristics of Hot Arid Environments

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