Tropical Climates

Question 1

Describe the Walker Circulation

Answer 1

Point to have:

• Easterly trade winds moving warm water from the Eastern to Western Pacific
• Pooling of warm water at the Western coast drives the thermocline downwards
• Low pressure conditions created, as warm air above the water rises
• In the east, cold water wells up after warm water migrates to the west
• Easterly trade winds form the north-flowing Peruvian current
• Rising air over the Western Pacific feeds return airflow, closing and strengthening the circulation
• Subsidence resulted in the East

Question 2

Describe El Nino

Answer 2

• Walker circulation has broken down
• Easterly trade winds weaken or reverses such that wind flows from the West to the East
• Warm water pools at the Eastern coast, causing low pressure conditions and a wet season
• Cold water in the Western Pacific reduces evaporation, encouraging drier conditions

Question 3

El Nino statistics

Answer 3

• Peru saw 2500mm of rain in a 6-month period, 300 times the average
• Eastern Australia endured the worst drought in 1982, losing $2000million in agriculture

Question 4

Statistics for the Af climate type

Answer 4

Singapore - Annual Temperature Range: 25-32 degrees Diurnal Temperature Range: 25-33 degrees
Rainfall: 2340mm a year
Kisangani, Congo - Average rainfall: 1804mm
Average Temperature: 25.4 degrees

Question 5

Statistics for the Am climate type:

Answer 5

Cochin, India: Annual temperature range of 3.3 degrees, total of almost 3000mm of rainfall in a year
Western Ghats (Gujarat) - less than 400mm a year

Question 6

Statistics for the Aw climate type:

Answer 6

Lagos, Nigeria: Average rainfall of 1780mm, average temperature 26.7 degrees

Question 7

Statistics for the BSh climate type:

Answer 7

Kayes, Mali - Annual temperature of 74 cm, 10.7 degree range annually

Question 8

Statistics for the BWh climate type:

Answer 8

Atacama desert, Chile - Annual rainfall of 15mm, diurnal temperature range of up to 35 degrees

Question 9

Describe the African monsoon (January)

Answer 9

• ITCZ migrates southwards (Capricorn)
• African continent loses heat faster than the surrounding Atlantic Ocean
• Winds blow out of Africa into the Gulf of Guinea and Atlantic Ocean
• Majority of landmass experiences dry spell because north east trade winds (harmattan) dominate most of West Africa, and they are dry and dusty
• Outliers include coastal zones as the southwest monsoon brings rain when it travels onshore to converge at the ITCZ

Question 10

Describe the African monsoon (July)

Answer 10

• ITCZ migrates northwards (Cancer)
• Landmass gains heat faster than the Atlantic Ocean, creating a low pressure area over Western Africa
• Thermal capacity of water is higher, air over it is colder, denser and sets up high pressure area
• South east trade winds cross the equator and are deflected to become South West monsoon winds
• Blows over the hot landmass and facilitates convective uplift
• Convergence uplift takes place at the ITCZ when northeast trade winds and southwest monsoon winds converge