Desert
In a dust storm, dust can be transported across continents and oceans depositing on _____
Land, ice and wated
Drought tolerance
Leave shed during dry periods to conserve water in the stems or resinous leaf coatings that retard water loss, extensive and often very deep root systems
Cold deserts are present in ______ and _____
Siberia, Antartica
Barchan Dunes
Solitary, crescent shaped dunes
Vegetation in deserts is _____, have a ____ appearance, and have ____ leaves, which are rarely green
Spiny, swollen, tiny
Sand dunes are ____ on the leeward side and ____ on the windward side
Steeper, gently sloping
____ and ____ fans do exist in deserts
Streams, alluvial
Isolated torrential downpours cause ______ with powerful _____ because the desert can't absorb the water easily
Strong runoff, flash floods
Types of deserts
Subtropical desert, rain-shadow, coastal, continental interior, polar
Star dunes are the most complex type of dune because they form in areas where _____ varies significantly, resulting in significant vertical _____ and may remain ____ for centuries
Wind Direction, build-up, stationary
dust devil
a small whirlwind or air vortex over land, visible as a column of dust and debris.
Barchan dunes only form where wind supply is ____ and sand supply is _____
constant, limited
Deflation of a desert surface might result in this forming?
desert pavement
sand dunes
hills of sand shaped by the wind
Hadley cells are
large-scale atmospheric convection cells in the tropics, extending between the ITCZ and the tropics of Cancer or Capricorn
Polar Deserts (Cold)
occurs where precipitation is extremely low due to sinking cold, dry air. They are underlain by ice. (Northern Greenland and Siberia and Antarctica)
longitudinal dunes
-Narrow, linear sand ridges with a broadly symmetrical profile aligned parallel to the prevailing wind direction -Form from prevailing direction of wind having slight varnish
parabolic dunes
-U-shaped dunes with the horns pointing upwind due to the role vegetation plays -Develop in area of partial vegetation and along coastlines with strong winds and abundant sand
subtropical high
A belt of high pressure located at approximately 30o N and 30o S, which pushes heavy subsiding air outward toward both north and south.
dust storm
A condition in which strong winds carry dust over a large area, usually during drought conditions.
desert varnish
A dark, rusty-brown coating of iron oxide and magnesium oxide that accumulates on the surface of the rock.
transverse dunes
A series of long ridges oriented at right angles to the prevailing wind; these dunes form where vegetation is sparse and sand is very plentiful.
Gigantic _____ provide evidence for erosion in valleys and canyons
Alluvial fans
Nutrients are brought from Western African dust to fertilize _____
Amazon rainforest
The _____ in Uzbekistan has an internal delta and flows through a desert
Amu Darya
Permanent streams exist in some deserts but only when it originates in ______
Areas with temperate or tropical climates
Desert varnish is only found in _____ and forms through interaction between ____, ____, and _____ on rock surfaces
Arid climates, dust, moisture, microbes
Desert is based on an area's _____, not a _____
Aridity, temperature
____ is one of the driest places on Earth
Atacama Desert
_____ are coastal deserts
Atacama, Namib
Atacama is dry because of the ______, in the rain shadow of the _____ and close to the _____
Cold Humboldt Current, Andes, subtropical zone
Coastal deserts form along coasts with ______
Cold ocean currents
Vegetation's Main Adaptive Strategies
Drought tolerance, succulence, drought avoidance
star dunes
Dunes that are isolated hills of sand that exhibit a complex, star like form. Develop where wind patterns are changing.
formation when local small pocket of hot air at the surface rises in the cooler, less buoyant air above resulting in spinning of cooler aid
Dust devil
Wind that Carrie sediment has strong ______
Erosionad power
Drought avoidance
Escape unfavorable conditions by not existing, I.e. germination only during a narrow window of time, when enough moisture is available, maturation in a short period, then death after channeling all energy into producing seeds
Aridity not only depends on rainfall but also on the rate of ______, and where this rate is sporadic or continuous
Evaporation
Ephemeral streams
Fast flowing creeks and streams, which will dry up shortly thereafter
Only ____ are transported in dust storms
Fine fraction
In desert wind, suspended load consists of ______ sediment like dust and silt while surface load consists of _____ such as sand
Fine-grained, coarse-grained
Transverse dunes form only on _____ areas where wind is ____ and sand supply is _____
Flat, barren, constant, high
Different types of deserts depend on the _____ setting
Geological
____ are continental deserts
Gobi, Taklamakan
lag deposit
the coarse sediment left behind in a desert after wind erosion removes the finer sediment
When sand dunes migrate, ____ results
Cross-bedding
Vegetation inhibits _____
Deflation
Dust storms from Central Asian deserts fertilizes ______
Hawaiian islands
Cold ocean water cools the overlying air by absorbing ____, and the resulting cool, relatively dry offshore air becomes _____ as it blows onshore and evaporates ______
Heat, heated, moisture
Air sinks in the _____, the pressure sinks, heating the air up. The air absorbs ______ and results in dry conditions with no _____
Subtropics, moisture, clouds
Abrasion
The grinding away of rock by other rock particles carried in wind
A desert is a dry area wheee average rainfall is less than ____ per year, vegetation coves less than __% of the land surface, no permanent streams or ______ streams
25 cm, 15, ephemeral
Deflation
Lowering of the land surface by removal of the finer fraction of sediment
Longitudinal dunes form behind ____ where sand supply is _____, wind is ____ but somewhat ____
Obstacles, moderate-high, constant and strong, variable in direction
Multifaceted ventifacts
Often found in deserts due to the abrasion of wind and the change in direction of the abrading wind
Desert varnish is often used as canvas for _____
Petroglyphs
In deserts, wind has direct access to the ground due to lack of ____
Plant cover
trade winds
Prevailing winds that blow northeast from 30 degrees north latitude to the equator and that blow southeast from 30 degrees south latitude to the equator
The progression from San Francsco to Death Valley is a result of the ______
Rain shadow effect
Death Valleyis in the _____ of the Rockies and is one of the most extreme deserts, because it is _____ sea level and close to the _____
Rain shadow, below, subtropical zone
In a ____ desert, air picks up moisture, rising air cools and rain clouds form. Once air moves across mountain, air is warmer and dryer resulting in a desert
Rain-shadow
Petrogyphs
Rock carvings of animals on desert varnish
Largest desert is in ____
Sahara
________ deserts are subtropical
Sahara, Kalahari, Arabian, and Australian
Like flowing waters, wind transports sediment both as ____ and _____
Surface load, suspended load
_____ are Rain-Shadow Deserts
The Great Basin, Patagonian
Very little precipitation in the Earth's polar regions, because of the ______ and _____
The general global air circulation causes the air to be dry over these regions, cold air holds very little moisture
Central Asian Deserts
These deserts result As air moves across a continent, for long distances such as over Asia, it gradually loses moisture via rainfall and
In a _____ zone, there is a lot of deflation
Trade winds
Parabolic dunes form in areas with partial ____, are common along ____ with strong ______ with ___ sand supply
Vegetation, coastlines, onshore winds, abundant
Succluence
Water storage in thick fleshy leaves and stems, water-efficient variant of photosynthesis using CO2 that is taken up at night and stored inside leaves, spiny or toxic to protect themselves from thirsty animals