Lesson 16: Deserts and Winds Flashcards
How are deserts defined?
Arid regions with average annual rainfall less than 250 mm
How are steppes defined?
Semi-arid regions that get 250-500 mm of rain annually
What are the different types of deserts? (6)
- Subtropical Deserts
- Continental/Mid-latitude Deserts
- Rain Shadow Deserts
- Coastal Deserts
- Monsoon Deserts
- Polar Deserts
How are Subtropical Deserts Characterized?
Trade winds that blow east to west, just north and south of the equator.
Where are Subtropical Deserts found?
Hoarse latitudes are centered between 20 degrees and 30 degrees North and South latitude.
What is an example of a Subtropical Desert?
Sahara Desert
How are Continental/Mid-latitude Deserts characterized?
Wide rage of annual temperatures
Where are Continental/Mid-latitude Deserts found?
Between 30 and 50 degrees N and S of the Equator in interior drainage basins far from the source of moisture.
What is an example of Continental/Mid-latitude Deserts?
Sonoran Desert in North America
Gobi and Taklamakan Deserts in Central Asia
How are Rain Shadow Deserts Characterized?
A desert formed in the lee-side “shadow” of the mountain range
Where are Rain Shadow Deserts found?
In Mountainous areas
Give an example of rain shadow deserts.
Turpan Depression in the rain shadow desert of the Tian Shan of China
Death Valley National Park, California in the rain shadow of the Sierra Nevada mountains.
Characterize Coastal deserts.
Affected by cold ocean currents that are parallel to the coast with local wind systems that dominate the trade winds
Where are Coastal Deserts found?
In the western edges of continents near the Tropics of Cancer (23.5 degrees N) and Capricorn (23.5 degrees S)
Give an example of a Coastal desert.
Atacama Desert, South America
Namib Desert, Africa
Characterize Monsoon deserts.
Wind system with pronounced seasonal reversal
Give an example of a Monsoon desert.
Thar Desert of India/Pakistan
Characterized polar deserts.
Mean temperature during the warmest month of less than 10 degrees C
Give an example of a polar desert.
Northern Greenland
Ice-free areas of Antarctica
Why is mechanical weathering dominant in arid regions?
Chemical Weathering requires water
What type of running water is more dominant in arid regions? (ephemeral or perennial)
Ephemeral
How does wind cause erosion?
- By deflation
- By abrasion
What does deflation produce?
- blowouts
- desert pavement
What are blowouts?
Shallow depressions produced by deflation
What is desert pavement?
a veneer of pebbles and cobbles
What does abrasion create?
- ventifacts
- yardangs
- mesas and buttes
How is sediment transported by wind?
- Bed load
- Suspended load
How is bed load characterized?
Consists of mostly sand-sized particles
Sand moves across the surface in a process called saltation
How is suspended load characterized?
Consists of mostly slit sized particles that are carried high into the atmosphere
How can you identify an asymmetric dune’s windward and leeward slope?
Windward: gently inclined
Leeward: angle of repose at ~35 degrees
What is loess?
large deposits of windblown dust
What are the different types of sand dunes? (6)
- Barchan
- Transverse
- Barchanoid
- Longitudinal
- Parabolic
- Star
Arid regions get ____ mm of rain per year
less than 250
The world’s largest desert is ____.
The Sahara Desert of North Africa
Subtropical/Trade Wind deserts lie between ____ degrees north and south
20 and 30
Ephemeral streams are also called
wadis
washes
arroyos
nullahs
___ does most of the erosional work in deserts.
Running water
As air rises over mountain ranges, water is precipitated and the air loses its moisture content. As a result, a desert is formed in the ____ “shadow” of the range.
leeward
The suspended load (wind) consistes mostly of ____ -sized particles.
silt
___ is the lifting and removal of loose material by the wind.
Deflation
___ are stones that are shaped and polished by wind abrasion
ventifacts
