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Global Distribution


Describe and explain the global-scale distribution of cold and high altitude environments (polar, glacial areas, periglacial areas, high mountains in non-polar places) and hot arid environments (hot deserts and semi-arid areas)

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Global Distribution


Describe and explain the global-scale distribution of cold and high altitude environments (polar, glacial areas, periglacial areas, high mountains in non-polar places) and hot arid environments (hot deserts and semi-arid areas)

TWO EXTREME ENVIRONMENTS

Hot, arid environments

  • hot deserts
  • semi-arid areas

Cold and high-altitude environments

  • polar areas
  • glacial areas
  • periglacial areas
  • high mountains in non-tropical latitudes
 
 

global distribution

 

TASK: Show the global distribution of extreme environments on a blank world map

 

DESCRIBING DISTRIBUTION

Global Subregions (UN)

Global Subregions (UN)

Distribution refers to the way something is spread out or arranged over a geographic area. 

Describe the distributions using the words below to help you. Check your answers by hovering over the images.

 

north/south/east/west                          named continents/regions                         coastal/inland                     highest/lowest                                         hemisphere                            tropics/mid latitude/polar    

In coastal areas. Highest in south west coast. Lowest north east coast and interior.

In coastal areas. Highest in south west coast. Lowest north east coast and interior.

Found in all regions of the world. Highest concentrations in northern hemisphere. Lowest in central Asia, northern North America.

Found in all regions of the world. Highest concentrations in northern hemisphere. Lowest in central Asia, northern North America.

Highest densities in south. Mainly extreme south and south west borders. Very low densities in north.

Highest densities in south. Mainly extreme south and south west borders. Very low densities in north.

 

TASK: Add labels describing the location of extreme environments

EXPLAINING the GLOBAL DISTRIBUTION OF HOT, ARID ENVIRONMENTS

EXPLAINING GLOBAL DISTRIBUTION OF COLD AND HIGH ALTITUDE ENVIRONMENTS

Namib Desert. Namibia, South West Africa.

Namib Desert. Namibia, South West Africa.

Cold and high-altitude environments are generally found along constructive plate margins, where fold mountains form, or polar regions.

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Fold Mountains

Constructive plate margins

Mountainous regions have a high elevation, where atmospheric pressure is lower which causes lower temperatures.

elevation pressure.jpg

The sun's rays are received more easily, however, more solar radiation is reflected due to the high reflectivity of snow.

albedo snow.jpg

At higher latitudes less heat penetrates the atmosphere as it is thicker and spread across a greater area.

Latitude and solar radiation

Latitude and solar radiation

Hot, arid environments are found in the tropics. These areas receive direct sunlight in summer and winter.

Tropics and sunlight

Tropics and sunlight

Hadley cells in the atmosphere also cause aridity as the warm moist air rises from the equator.

This condenses and precipitates and the cooler air sinks over the tropical latitudes. The air is drier as cool air cannot hold as much moisture. The air then heats as it spreads over tropical regions and rises again.

Hadley cells and climate

Hadley cells and climate

Hot, arid climates can also be found in rain shadows, mountainous regions with arid areas behind them. The mountains cause relief rainfall and then the dry air blows across the landscape drying it out.

Rain shadow effect

Rain shadow effect

 

TASK: Add labelled diagrams to your world map that explain the location of extreme environments.  Read pp 107-108 and add extra information.

 

REVIEW

Form pairs with person A unable to see the diagrams. Person B describes the picture for A to draw.

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Relief and Climate


Describe the relief and climatic characteristics that make environments extreme, including unreliability and intensity of rainfall in arid environments and the risk of flash floods

Relief and Climate


Describe the relief and climatic characteristics that make environments extreme, including unreliability and intensity of rainfall in arid environments and the risk of flash floods

Describe the climate of the two places below. Include data in your answer.

 

task

  1. Use the following resources to find out information on the climate and relief of different extreme environments:

    • the resources on this page

    • 108-109 of course book

    • internet research

 

resources

 
 

FLASH FLOODS

car flash flood.jpg

In order to understand how a flash flood like the one above can happen in hot, arid areas, we must first understand how drainage basins work.

Look at the diagram below. How would the drainage basin system and the processes responsible for transferring water be different in hot arid areas?

drainage basin system.jpg

Flooding occurs when rainfall intensity exceeds infiltration capacity generating surface runoff/overland flow leading to flooding.

Causes of flooding in deserts:

  1. summer convection rainfall bringing high amounts of precipitation

  2. unvegetated desert surfaces reduce interception and infiltration, increasing overland flow

  3. high concentrations of water in wadis, gullies or channels

  4. presence of desert crusts (duricrusts) and other barriers to infiltration (rocks in desert pavement etc).

 

CONVECTIONAL RAINFALL

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INFILTRATION RATES IN DESERTS

TASK

Draw a labelled diagram to illustrate how flash floods happen in hot, arid environments.

Use all of the information above to help you.

 

practice exam question

Describe the climatic characteristics of either periglacial or glacial environments. [4 marks]

 

Mark Scheme

Key aspects will be temperature, temperature range, seasonality, precipitation.

Award 1 mark for each valid statement, supported by some quantification or development.

 


permafrost periglacial spring russia.jpg

Challenges of Extreme Environments


How relief, climate, human discomfort, inaccessibility, and remoteness present challenges for human habitation and resource development

Challenges of Extreme Environments


How relief, climate, human discomfort, inaccessibility, and remoteness present challenges for human habitation and resource development

Review the climate and relief of:

  1. Cold and high-altitude environments (polar, glacial areas, periglacial areas, high mountains in non-tropical latitudes)

  2. Hot, arid environments (hot deserts and semi-arid areas)

Calculate and label the following: 

  • Precipitation: type, annual & monthly rates

  • Temperature: annual range, monthly averages

  • Seasonal differences

When would freeze-thaw weathering likely be  most active?

 

PERIGLACIAL ENVIRONMENTS

 

PERMAFROST & PERIGLACIAL ENVIRONMENTS

A periglacial landscape. Jackson Hole, USA

A periglacial landscape. Jackson Hole, USA

Periglacial environments have a cold climate and are frequently marginal (next to) to glacial environments. Subject to intense cycles of freezing and thawing of superficial sediments. 

Permafrost is soil, rock or sediment that is frozen for more than two consecutive years. Permafrost is closely associated with periglacial environments and permafrost processes take place within a periglacial environment

 

CHALLENGES OF PERMAFROST

Access the resources and make notes on how periglacial environments create challenges for human habitation and resource development, as well as the measures used to overcome them.

 

HUMAN HABITATION AND RESOURCE DEVELOPMENT

Illustrate the challenges and explain how they affect human habitation and resource development.

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Agriculture in the Mojave Desert, USA

Agriculture in the Mojave Desert, USA

 
 

RESOURCE DEVELOPMENT / CASE STUDY: THE TRANS ALASKA PIPELINE

INTRODUCTION

 
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Reasons for low population density


Explain the other factors responsible for a low density of population in these areas: human discomfort, inaccessibility, remoteness.

Identify ways in which people adapt their activities to extremes of weather and climate.

Reasons for low population density


Explain the other factors responsible for a low density of population in these areas: human discomfort, inaccessibility, remoteness.

Identify ways in which people adapt their activities to extremes of weather and climate.

population density map.jpg

Extreme environments typically have low population densities. Why?

 

 

 

human discomfort                  inaccessibility                        remoteness

 
 

HUMAN DISCOMFORT

 
 
 

ways in which people modify their activities in extreme environments

sahel 2.jpg

 

  1. Read p 82 of your study guide
  2. Create a picture or collage illustrating the ways in which people modify their activities in Extreme Environments
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Changing Distribution


Describe and explain the changing distribution of extreme environments over time, including the advance and retreat of glaciers and natural desertification

Changing Distribution


Describe and explain the changing distribution of extreme environments over time, including the advance and retreat of glaciers and natural desertification

List as many causes of climate change as you can. Prepare to share these with the class.

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NATURAL CLIMATE CYCLES

Human activity is undeniably linked to an increase in CO2 in the atmosphere, which is changing the Earth’s climate. However, climate has been constantly changing throughout history.

If the distribution of extreme environments is dictated by the type of climate, changes to climate therefore influence the distribution of extreme environments. In order to understand historic changes to the distribution of extreme environments, we must therefore first understand that natural changes to climate have influenced the distribution of extreme environments over time.

Watch the video above and make notes on the natural causes of climate change.

 

CLIMATE CHANGES AND GLACIAL ENVIRONMENTS

What are the different types of glacier?

How do glaciers form?

Why are glaciers an important resource for humans?

How are glaciers changing and what are the causes for this?

 

GLACIAL SYSTEM

Glaciers are the products of a system which includes inputs, storage and outputs. The balance between these is called the glacial budget or glacial regime.

 
Fig. 1 Glacial budget diagram

Fig. 1 Glacial budget diagram

 

INPUTS

  • Snow accumulation

  • Avalanches

  • Debris

  • Heat

  • Meltwater

STORES

  • Ice

  • Water

  • Debris

  • Moraine

OUTPUTS

  • Ablation (ice > water)

  • Sublimation (ice > vapour)

  • Sediment

 

GLACIAL BUDGET

accumulation > ablation, glacier advances

accumulation < ablation, glacier recedes

accumulation = ablation, glacier maintains same size

 
 
 

CLIMATE CHANGE AND HOT, ARID ENVIRONMENTS

Desertification is a type of land degradation in which a relatively dry area of land becomes a desert, typically losing its bodies of water as well as vegetation and wildlife. It is caused by a variety of factors, such as through natural and anthropogenic (human caused) climate change (particularly the current global warming) and through the overexploitation of soil through human activity.

Fig. 2. Desertification in the Sahel region of Mali

Fig. 2. Desertification in the Sahel region of Mali

When deserts appear automatically over the natural course of a planet's life cycle, then it can be called a natural phenomenon; however, when deserts emerge due to the rampant and unchecked depletion of nutrients in soil that are essential for it to remain arable, then a virtual "soil death" can be spoken of, which traces its cause back to human overexploitation.

Desertification is a significant global ecological and environmental problem with far reaching consequences on socio-economic and political conditions. (Source)

 

HUMAN-CAUSED DESERTIFICATION

 

NATURAL DESERTIFICATION