Low Latitude Climates

Rev 3-13-2002

 

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Group-I: Low Latitude Climates

Compare the four climographs (Again) Climographs for four low-latitude climates: Wet equatorial (Af), Monsoon and Tradewind coastal (Am), Wet-dry tropical (Aw), and Dry tropical (BW)

  • Compare the four climograph patterns, side-by-side
  • Focus on annual cycles of temperature and precipitation
    • Jaluit, Marshall Islands -- 82° F (28° C), 159 in (404 cm)
    • Aparri, Phillipine Republic -- 81° F (27° C), 89 in (226 cm)
    • Raipur, India -- 81° F (27° C), 53 in (135 cm)
    • Khartoum, Sudan (Africa) -- 85° F (29.5° C), 6 in (15 cm)

(1)  Wet Equatorial Climate/Tropical Rain Forest Climate : Köppen Type = Af   Map showing location of Iquitos, Peru, South America, Wet equatorial (Af) climate    Map showing location of Iquitos, Peru, South America, Wet equatorial (Af) climate
       Note: "Tropical Rain Forest" is a vegetation association and not a description
       of a climate's characteristics or of its controls.

  • Iquitos, Peru, Lat 3 ° S, upper Amazon Lowland Climograph for Iquitos, Peru, South America, Wet equatorial (Af) climate
    (See Fig 6-6: Uaupés, Brazil, for your text reference.)
  • Uniform temperatures near 80° F (27° C)
  • Daily temp variation greater than monthly!
  • Annual temperature range = 4° F (2.2° C)!
  • Abundant rainfall in all months
  • Annual precipitation = 103 in (262 cm)
  • Dominated by the ITC, all year, with its convectional rainfall
    • ITC = Intertropical Convergence Zone

(2)  Trade-wind Coastal Climate: Köppen Type = Am    Map showing location of Belize, Central America, Tradewind coastal (Am) climate
       Note:  Your text appears to not single out this climate type, which is
       distinguished here by its controls even though it is a Köppen "Monsoon"
       climate based on its temperature and precipitation data.

  • Rain can be accentuated by coastal mountain uplift
  • Belize, Central American east coast, lat 17° N Climograph for Belize, Central America, Tradewind coastal (Am) climate
  • Temp. has annual cycle with modest change
  • Temperature range = 9° F (5° C)
  • Warmest in high-sun season
  • A lot of rain, but annual cycle -- 79 in (201 cm)
  • Rain from moist trade winds
  • Least rain after low sun period
  • More rain when ITC nearby  

(2)  Tropical Monsoon Climate: Köppen Type = Am    Map and climograph: Tropical monsoon (Am) climate, Cochin, India

  • Cochin, India -- west coast, lat 10° N
    (See Fig 6-7: Yangon, Myanmar, for your textbook reference.)
  • Extreme rain peak summer monsoon season
  • Over 26 in precip. in wettest month
  • 115 in (292 cm) annual total precip
  • Almost dry season -- Dec, Jan, Feb
  • Heavy rain almost makes up for drier period, vegetation wise
  • Season reversal of winds bring warm season precip
  • Low-Latitude Rainforest Environment
    •

    Some sources, other than your textbook, group several climate types together under a more encompassing "Tropical Rainforest":  1) Wet Equatorial (Af),  
    2)     Monsoon (Am), and 3) Trade Wind Coastal (Am) climates are lumped together.
    Your text prefers to name only the Wet Equatorial as Tropical Rainforest.
    Tropical Rainforest is a term used in various ways.  Be aware of this climatological connotation.

    (3) Wet-dry Tropical Climate/Tropical Savanna Climate: Köppen Type = Aw   Map showing location of Timbo, Guinea, west Africa, Wet-dry tropical (Aw) climate   Map showing location of Timbo, Guinea, west Africa, Wet-dry tropical (Aw) climate
           Note: "Tropical Savanna" is a vegetation association and not a description
           of a climate's characteristics or of its controls!

    • Timbo, Guinea, West Africa, lat 10 N   Climograph for Timbo, Guinea, west Africa, Wet-dry tropical (Aw) climate 
      (See Figs 6-9, [Mérida, Mexico], and 6-8, [Kenya, East Africa] in your text.) 
    • Wet high-sun season
    • Distinct temperature cycle -- hottest before rainy season
    • Temperature range = 9.7° F (5.4° C)
    • Dry low-sun season -- almost rainless
    • Precipitation total = 64 in (163 cm)
    • Alternating influence of STH (dry) and ITC (wet)
      • STH = Subtropical High; ITC = Intertropical Convergence Zone
    • "Savanna" vegetation associations occur here -- "big game" country of Africa
    • Savanna = grassy plain with scattered trees that are usually short and thorny.

    (4)  Dry Tropical /Hot Low-Latitude Desert Climate: Köppen Type = BWh     Map showing locatin of Wadi Halfa, Sudan, in the Sahara Desert, NE Africa, Tropical dry (BW) climate    Map showing locatin of Wadi Halfa, Sudan, in the Sahara Desert, NE Africa, Tropical dry (BW) climate
           

    • Map of dry tropical and dry subtropical:  Wadi Halfa, on the Nile River, Sudan, Africa, 22° N    Climograph for Wadi Halfa, Sudan, in the Sahara Desert of NE Africa, Tropical dry (BW) climate
      (See Fig 6-22, Ar Riyãdh, Saudi Arabia for your textbook example.)
    • Strong annual temperature cycle, compared to other tropical climates already studied, but less than higher latitude climates
    • Intensely hot temperatures in high-sun season
    • World record for diurnal (daily) temperature range -- over 100° F ! in this climate type!  Radiation cooling is rapid at night; heating quickly in sunlight.
    • World's record for hottest temperature recorded also in this climate type.
    • Very low precipitation -- too little to show
    • Precipitation is highly irregular and unreliable
    • Precipitation statistics can be very misleading
    • Subtropical High pressure zone very dominant
    • These are hot dessert (arid) climate zones ...

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