Relief & Climate Characteristics (DP IB Geography)
Revision Note
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)
Hamada desert | Reg desert | Erg desert |
Desert landscapes are diverse due to:
Geological factors (tectonics and rock type)
Climate: temperature, rainfall and wind
Weathering and mass movement processes
Time
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