Causes Of Aridity Flashcards
(14 cards)
What are the 4 causes of aridity in deserts?
Global atmospheric circulation
Cold ocean currents
Continentality
Rain shadow effect
What is the ITCZ?
Inter-tropical convergence zone
What is the global atmospheric circulation?
Winds are created as air moves from areas of high pressure to low pressure. This leads to the dry air in deserts due to the moisture in the sinking air being dry.
What are cold ocean currents?
Several deserts lie on the western coasts of continents where there is an upwelling of cold water due to the circulation of wind currents.
What does the cold water in the ocean currents do?
This cold water on the surface decreases the temperature of the overlying air mass and so reduces the amount of rainfall.
What is an example of a desert that the air mass blows over the land?
Atacama desert
What is continentality?
If the air mass moves over a continent it will lose moisture due to rainfall due to low evaporation rates.
What is an example of a desert with continentality?
Gobi
What is the rain shadow effect?
Tall mountain ranges, such as the Andes, force air to rise on the windward slopes as pressure decreases and the air cools, condenses and cloud formation occur and
produces rain.
Which is the wetter side of the mountain range?
Windward slopes
Why does the global circulation system cause aridity?
Located on Hadley Cell
What is used to classify deserts?
Aridity Index
What is the water balance?
The relationship between mean annual precipitation and potential evapotranspiration
Why does the circulation system being located on Hadley cell cause aridity?
Air rise and cools so moisture condenses and falls as rain leaving the air dry
Air dry descends in a zone of high pressure so no moisture can be brought in by the wind
