Rainforests And Deserts

Question 1

Rainforest climate

Answer 1

30°C average monthly 
4°C annual range 
82% humidity 
4000mm annually 
6°C diurnal range 
5hours sunlight

Question 2

Factors influencing rainforest climate

Answer 2

Latitude - high insolation
Altitude - lowland, pressured air, denser + warmer
Atmospheric pressure - heavy rain
Near oceans - moisture
Diurnal temp range - afternoon rain, less cloud at night
Below rising limb

Question 3

Explain convectional rainfall

Answer 3

1. Insolation from Sun heats up surface of rainforest
2. Surface emits long wave radiation, warming overlying air with lots of water moisture
3. Air rises rapidly, cools + condenses (dew point) to form cumulus clouds
4. Water droplets collide, large, overcome updrafting rising air
5. Heavy afternoon convectional rainfall

Question 4

CS Amazon rainforest

Answer 4

Farming - slash & burn, 10km subsistence
Transport -5300km Trans Amazonian, 900km railway
Logging timber/mining iron ore & hydroelectricity
Carajas settlement

Less biodiversity (300/km2)  
Less O2 (less trees) - 1/3 from rainforest, global warming 
Land infertile (disrupt nutrient cycle) - less interception 
River pollution 
Less Amerindians (6m to 200,000) & culture

Question 5

Rainforest vegetation

Answer 5

300 species/km2 
Emergent 50m - tall to reach sunlight 
Canopy 40m (70% light) 
Thick waxy cuticle 
Buttress roots 
Large wide shrubs, lots of chlorophyll 
Lianas 200m long 
Drip tip leaves 
Humus layer, rapid decomposition 
Epiphytes 
Evergreen, growth & recycling not limited by low temps/light/rain

Question 6

Distribution of deserts

Answer 6

5-20° N & S of equator, sub tropics

Very high temps & less than 250mm rain/year

Question 7

Desert climate

Answer 7

35°C max
10°C min
40°C range - Jan/July
10mm monthly

Question 8

Factors affecting desert climate

Answer 8

High atmospheric pressure
Diurnal temp range - arid air, temp loss by radiation
Distance from ocean - rainshadow effect, no clouds
Cold offshore ocean currents - less evaporation
Under sinking limb
Less humid, no clouds, high insolation

Question 9

CS Sonoran desert - Yuma, Arizona

Answer 9

Lowering water table - irrigation in Phoenix (large underground aquifers)
Urban sprawl, flooding (dams)
Marana agriculture of cotton - soil salinity & infertility
Tourism
Copper mine near Ajo
USA military bases

Destroys habitats & ecosystems
Flooding (Lake Saguro, Phoenix)
Overgrazing destroys soil

Question 10

Rainshadow effect in Sonoran Desert (little rainfall) - Sierra Nevada mountain range

Answer 10

High summer temp - July 25-42°C
Cooler in January - Jan 5-18°C
100mm/year

Also under sinking limb of Hadley cell: Air descends, temp increases, humidity decreases - no cloud

Rainshadow effect:

1. Air from west (Gulf of California) forced to rise over mountains
2. Cools - high rain on windward side
3. Descends on leeward side - little moisture in Sonoran

Question 11

Desert vegetation

Answer 11

Sparse (low rain/soil)
Xerophytes - Cacti store water
Spines/thin leaves - less evapotranspiration
Long, deep & wide roots - Creosote bush
Dormant then quickly germinate - Joshua tree, short life cycle
Succulent leaves/stem - Yucca/Cacti
Stomata on underside close

Nocturnal animals & camels

Question 12

Distribution of a rainforest

Answer 12

Equatorial areas between tropics - 5° N & S of equator

6% earth’s surface