3.5 Arid climates

3.5 Arid climates
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Slide 1: Tekstslide
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3.5 Arid climates

Slide 1 - Tekstslide

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 - Tekstslide

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 - Tekstslide

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 - Tekstslide

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

Slide 5 - Tekstslide

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 - Tekstslide

The steppe landscape in the Sahel (Senegal).

Slide 7 - Tekstslide

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

Slide 8 - Tekstslide

Slide 9 - Video

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

Slide 10 - Tekstslide

Atmospheric circulation and prevailing wind directions.

Slide 11 - Tekstslide

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

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

Polar front / subpolar minimum
Area of low atmospheric pressure located in the middle latitudes; the air mass rises.

Slide 12 - Tekstslide

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.

Slide 13 - Tekstslide

Prevailing wind direction = most common wind direction.

Slide 14 - Tekstslide

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

Slide 15 - Tekstslide

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.

Slide 16 - Tekstslide

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

Slide 17 - Tekstslide

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.

Slide 18 - Tekstslide

Havo: Look at the planner in Teams for the exercises you have to do.

Slide 19 - Tekstslide

Slide 20 - Video

Vwo: Look at the planner in Teams for the exercises you have to do.

Slide 21 - Tekstslide