This lesson contains 20 slides, with text slides and 2 videos.
Lesson duration is: 30 min
Items in this lesson
3.5 Arid climates
Slide 1 - Slide
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 = 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
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).
Slide 5 - Slide
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).
Slide 7 - Slide
The Great Green Wall is an initiative designed to stop the desertification of the semi-arid Sahel region in Africa.
Slide 8 - Slide
Slide 9 - Video
What problems do humans face when they live in a desert climate?
Slide 10 - Slide
Atmospheric circulation and prevailing wind directions.
Slide 11 - Slide
Area of high atmospheric pressure located in the subtropics; the air mass descends.
Area of high atmospheric pressure located in the polar regions; the air mass descends.
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.
Slide 13 - Slide
Prevailing wind direction = most common wind direction.
Slide 14 - Slide
Prevailing wind direction
Most common wind direction in the middle latitudes; a wind that blows from west to east.
Slide 15 - Slide
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 - Slide
The northern Atacama Desert is located in the rain shadow of the Andes Mountains.
Slide 17 - Slide
Slide 18 - Video
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.