Reasons for aridity

Question 1

Mnemonic???

Answer 1

A CROW

A Atmospheric Circulation
C Continentality
R Relief 
O Ocean Currents
W Winds

Question 2

Atmospheric Circulation

Answer 2

At equator warm air rises
Forms area of low pressure
Air pushes up and spreads out
Air cools and sinks
Forms area of high pressure
Coriolous effect moves the areas of high and low pressure
Transfers heat and moisture
In the ITCZ
Within the falling limb of the Hadley Cell

Question 3

Continentality

Answer 3

Further away from the ocean a desert is
More arid it will be
E,.g the Sahara is 2000 km from the sea

Question 4

Relief

Answer 4

Moist air brought in by prevailing wind
Forced over windward side of mountain
Condenses and rains on windward
Air descends on leeward
Air compressed and warmed
Leeward side receives no moisture
E.g. Arica in the Atacama

Question 5

Ocean Current

Answer 5

Thermohaline circulation takes cold water from the poles to the equator
Air is chilled to its dew point - condensing it
Mist / fog created
Warm air above it creates an inversion
Prevents warm air rising
Mist / fog burnt off by sun
Likelihood of rain decreases

Question 6

Winds

Answer 6

Wind is blown from an area of high pressure

Cannot receive moisture