Mojave

Question 1

Where are hot deserts located

Answer 1

Arid zone = 15-30 degrees north and south of the equator

Usually inland from coast (continentality)

Usually on the western side of continents

Question 2

What’s the climate like

Answer 2

Diurnal temperatures

(Warms quickly during day, little vegetation or clouds to absorb direct insolation)

(Looses heat quickly during the night due to little cloud cover and vegetation to act as insulation)

20-30+ degrees Celsius with low relative humidity - very dry

Often intense thunderstorms / rainfall when precipitation occurs

Rainfall Not common, but when it arises it’s usually short and sporadic with high intensity - usually recieve around 10 inches maximum annually of rainfall

Question 3

Challenges plants and animals face in deserts

Answer 3

Extreme temperature ranges m

Poor soil quality - lack of nutrients

Lack of moisture / water

Not much food or nutrition

Lack of shade

High temps

Intense rainfall in short periods

High winds and sandstorms

Question 4

Soil consists of…

Answer 4

Weathered rocks

Decaying matter

Air

Water

Question 5

3 layers of soil

Answer 5

Topsoil

Subsoil

Bedrock

Question 6

3 types of soil

Answer 6

Sand (large particles) - holds little water

Silt (smaller particles) - holds some water

Clay (smallest particles) - holds lots of water

Loam is best for plant growth

Question 7

Desert soils

Answer 7

Lack of moisture

High rates of evaporation - translocation can occur such as salinisation

Sparse vegetation cover

Thin humus layer with little nutrients due to lack of recycling

Question 8

Soil degradation and conservation

Answer 8

Over cropping

Over grazing

Deforestation

Unsustainable agriculture

Urbanisation

Question 9

Over grazing

Answer 9

Too many animals grazing in the same area

Plants cannot recover

Leads to bare patches with no plants

If plants do survive their roots never develop properly

CASE STUDY LINK - Sahel in 70s and 80s- wealth defined by number of cattle - leads to very high stacking and pop density , exasperated by drought

Question 10

Over Cropping

Answer 10

Depletes soil nutrients

Makes the soil friable (dry and susceptible to wind erosion)

Nutrients aren’t restored

Increased risk of crop failure and then wind erosion

CASE STUDY LINK - dustbowl - 1930s American Midwest
Over use of land
Wind erosion
Soil and dust moved many thousands of kms

Question 11

Deforestation

Answer 11

Leads to exposure of soil - water and wind erosion (sheet flooding) and (sediment transport via aeolian processes such as suspension and traction) which removes layers of soil

Question 12

Outline the atmospheric processes that cause aridity

Answer 12

Cells of air meet at the itcz from the ferrel cell

Sun heats the ground and air above it
becomes hot

The hot air contains large amounts of water vapour from transpiration or ground

This heated air rises in form of convection currents, then cools and condensed

Causes thick clouds and torrential rain

The air that has risen stops when it cannot rise anymore at the tropopause (altitude of 14km)

It cannot continue to rise so rising air from underneath pushes it horizontally outwards

As air flows away from its main heat source , the equator, it cools

Cooling makes the air denser, and much of this denser, heavier air sinks back towards the earth at 30 degrees north and south of the equator (very dry air as it’s lost moisture from precipitation over the equator)

The sinking produces high pressure air mass which is warm because it is heated by compression (creates anti cyclonic conditions)