3.5 Arid climates

3.5 Arid climates
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AardrijkskundeMiddelbare schoolhavo, vwoLeerjaar 3

This lesson contains 21 slides, with text slides and 2 videos.

time-iconLesson duration is: 30 min

Items in this lesson

3.5 Arid climates

Slide 1 - Slide

Learning objectives
After studying this section, you will be able to:
  • Describe two different arid climates
  • Explain why the world’s deserts are arid

Slide 2 - Slide

Arid climates
Arid = Dry.

Desert climate (BW) = Climate zone with very little to no precipitation and high evaporation.

Steppe climate (BS) = Climate zone with some precipitation during the wet season, nearly balanced with evaporation rate.

Slide 3 - Slide

Deserts
Daily maximum and minimum temperatures vary wildly in some deserts: there are no clouds to reflect sunlight during the day or function as “insulation” during the night.

Slide 4 - Slide

Climate graph for Cairo, Egypt (BW).
Climate graph for Dakar, Senegal (BS).

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Steppe landscape
  • It has more vegetation than a desert landscape. 
  • This semi-arid climate remains too dry for most tree species to grow. 
  • Dominated by grasses and shrubs, but less than in the savannah climate.

Slide 6 - Slide

The steppe landscape in the Sahel (Senegal).

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The Great Green Wall is an initiative designed to stop the desertification of the semi-arid Sahel region in Africa.

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Slide 9 - Video

Talking point
What problems do humans face when they live in a desert climate?

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Atmospheric circulation and prevailing wind directions.

Slide 11 - Slide

Atmospheric circulation
Subtropic maximum
Area of high atmospheric pressure located in the subtropics; the air mass descends.

Polar maximum
Area of high atmospheric pressure located in the polar regions; the air mass descends.

Subpolar minimum
Area of low atmospheric pressure located in the middle latitudes; the air mass rises.

Slide 12 - Slide

Plurals of words with a Latin root
‘Minimum’, ‘maximum’ and ‘cactus’ are words that come from Latin. In Latin, a singular word that ends on ‘-um’, takes ‘-a’ in the plural, while singular words that end in ‘-us’, take ‘-i’ in the plural. So, ‘maximum’ becomes ‘maxima’ and ‘cactus’ becomes ‘cacti’. However, following normal English grammar you can instead add ‘-s’ or ‘-es’ to form a plural: ‘maximums’ and ‘cactuses’. The English language is shifting and both plural forms are now considered correct. For the word ‘maximum’, the Latin version ‘maxima’ is still preferred in science, but in less formal English usage, ‘maximums’ has become the norm.

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Prevailing wind direction
= most common wind direction.

Slide 14 - Slide

Prevailing wind direction
Westerlies
Most common wind direction in the middle latitudes; a wind that blows from west to east.

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Sea currents
Important factor in the location of deserts:
  • Cold water evaporates less easily than warm water;
  • Wind blowing from the sea to the land carries less moisture with it.

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The northern Atacama Desert is located in the rain shadow of the Andes Mountains.

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Slide 18 - Video

Essence
Arid areas exist in very different parts of the world and can be both hot and cold. Köppen differentiated between the desert climate and the steppe climate. The steppe climate is located on the edge of a desert climate. Deserts can form due to zones of high air pressure, the rain shadow created by mountain ranges, prevailing wind direction and cold ocean currents.

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Homework 3HT
Thursday 4 March, 3rd hour:
  • Read 3.5 and make a summary
  • Learn par. 1 - 4
  • Next lesson do ex. 1 to 4a, 5 to 9 and 12

Slide 20 - Slide

Homework 3VT
Thursday 20 February, 3rd hour:
Read 3.5 and do ex. 1 to 4a, 5 to 9, 11 and 12
Study 3.4

Slide 21 - Slide