Summary CIE Alevel Geography notes - tropical environments

Tropical environment

Tropical climate

• Latitud
- high angle of noon day sun
- intense heating
- high annual temperature (27°C
- low annual temperature range (2-3°C
- low pressure from rising air mass
- rainfall

• ITC
- thermal equator
- migrates with the changing position of the overhead sun
- convection rain band
- Northern hemisphere summer= 8-14°N, northern hemisphere winter= 2-8°
- More land mass in northern hemisphere; land heats up more than ocean due to low
speci c heat capacity

• Sub-tropical anticyclon
- Strong subsidence of air beneath anticyclones
- Prevents maritime time into seasonal humid areas in dry seasons

• Trade winds
- Steady, persistent
- Bring water vapour and latent heat into ITC
- North easterly trades (Northern hemisphere), south easterly trades (south hemisphere




Humid tropical climate (equatorial climate
- Within 10°N and
- Doldrum (no wind
- Convectional uplift of air
- Abundant and heavy rai
- High moisture carried in by trade winds (maritime air masses
- High temperatur
- Double maxima of rain- ITCZ moves over equatorial areas twice a year
- Small annual range of temperature

Case stud
• Singapor
- 1°
- Annual temperature of 27.5°C
- Annual temperature range of 1.5°



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, - Diurnal temperature range of 8°
- Convectional rainstorm in the afternoon
- Annual precipitation of 2415mm
- Average humidity 83


Seasonal humid tropical climate
Savann
- movement of ITC
- Between 23.5 N and S (Tropic of Cancer and Tropic of Capricorn
- Large annual temperature range
- Moderate annual precipitation
- Most rain in summer

Case stud
• Nigeri
- 9°
- Gulf of Guinea- south westerly prevailing winds bring in warm moist maritime air (wet
season
- North east trades (Harmattan winds) bring in dry hot continental air from the Sahara
desert (dry season
- Annual temperature of 23°
- Annual precipitation 700mm
- Above 100mm monthly from June-September (wet season); Below 15mm from October-
April (dry season)
- Annual temperature range of 12°C
- Different part experience different climate (equatorial, seasonal humid tropical of
savanna, semi-desert climates)

Monsoon
- Seasonal reversal of wind direction
- Inshore winds vs onshore winds
- Sub tropical jet strea
- Large annual temperature range of 8-11°

Cool dry winter (November- February)
- North east winter monsoon
- Westerly jet stream over India
- Air subsides and form anticyclone
- Offshore wind bringing dry cool continental air mass towards Bay of Bengal and the
Indian ocean
- Sri Lanka gets winter rain- offshore wind pick up moisture at Bay of Bengal and
becomes onshore wind onto north of Sri Lanka
- Monthly temperature 20°
- Monthly precipitation less than 2m
- Diurnal temperature range 12°C (lack of cloud

Hot dry spring (March- May)
- transition from north east winter monsoon to south west summer monsoo
- Intense isolation from overhead su
- Monthly temperature over 30°C
- Westerly jet stream starts to move north



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