Heidi tropical desert

Question 1

Where are most tropical deserts located?

Answer 1

Astride the tropics between lattitudes 15 and 30 western sides of continents

Question 2

Characteristics of tropical deserts

Answer 2

Hot summers Hot/warm winters Moderate annual ranges High daily temp ranges Very low rainfall - below 250mm Occasional torrential rain Rain rare + erractic High sunshine totals Low relative humidity High pressure Strong, constant, dry Trade winds 11

Question 3

Why do tropical deserts have seasons?

Answer 3

LATITUDE Temperature differences caused by Tilting of the hemispheres towards/away from the sun

Question 4

Why do tropical deserts have very hot summers and hot/warm winters?

Answer 4

LATITUDE Summer: Noonday sun at high angle in the sky Winter: Noonday sun’s angle is lower, but never very low

Question 5

Why do some tropical deserts with high altitude have colder temperature than places with lower altitude?

Answer 5

ALTITUDE Altitude increases = air temp decreases Rate: -0.6C every 100m

Question 6

Differences between coastal tropical deserts and in-land tropical deserts and why?

Answer 6

DISTANCE FROM THE SEA Coastal areas = warmer winters + cooler summers Water heats + cools more slowly than land Coastal areas = smaller annual temperature ranges Maritime influence

Question 7

What is maritime influence?

Answer 7

Air blowing from the sea brings temperature of sea to land

Question 8

Why do coastal deserts have lower summer temperatures than expected for their latitudes?

Answer 8

COLD OCEAN CURRENTS OFFSHORE Cold ocean currents off West coasts lower temps of coasts onshore winds are chilled by contacts with them

Question 9

Why don’t deserts have a lot of cloud cover?

Answer 9

Very low relative humidity

Question 10

What does lack of cloud cover lead to?

Answer 10

Extreme diurnal temperatures Very large daily temp ranges all year around

Question 11

Influence of pressure on precipitation in deserts?

Answer 11

Trade winds are strong, constant and dry. Combination of sinking air and dry offshore Trades

Question 12

What result in the directions of Trade winds?

Answer 12

Winds blowing out of high pressure areas into low equatorial zones. Winds deflected by Earth’s rotation Right in Northern Hemisphere Left in Southern Hemisphere

Question 13

Why do coastal deserts have very little rain?

Answer 13

COLD OCEAN CURRENTS OFFSHORE Cooling causes condensation over cold current, forming fog Moisture from air moving inland removed

Question 14

How does relief rain and rain shadow form?

Answer 14

RELIEF RAIN: - Moist air forced to raise by high ground - Air expands + cools -Condensation at dew point - forms clouds - Rain falls from cloud RAIN SHADOW: - Descending air compressed - Air warms - Relative humidity reduces - No rain

Question 15

What is relief rainfall?

Answer 15

Rainfall caused by winds crossing high ground

Question 16

How is a tropical desert formed?

Answer 16

Continentality (Areas lying deep within a continent = desert, air current lost all moisture) Cold ocean currents Rain shadow effect Hadley cells

Question 17

Why is rainfall so sparse in the desert?

Answer 17

1. Little rainfall due to cold oceans currents etc.
2. High evaporation (of any water that is left) due to high temperatures

Question 18

How are plants adapted to the desert?

Answer 18

1. Succulents store water in leaves, stems and fruit.
2. Seeds can stay dormant for years but germinate quickly when it rains.
3. Long taproots reach groundwater.
4. Horizontal shallow root systems catch water after it just rains.
5. Waxy cuticles decrease transpiration.
6. Low surface area in leaves (e.g. spines) reduces water loss.
7. Spines protect against animals.
8. Stomata open only at night.
9. Hairs on stems traps a water layer (more humid=less evaporation).

Question 19

Why do desert soils cause difficulties for plants?

Answer 19

1. Often very porous, so water passes straight through them after rain.
2. Sandy soils are mobile, so plants can be covered, and loose, providing little stability.
3. Desert soils are thin and contain little nutrients due to little organic matter decomposing.
4. Soils are saline - salts drawn to surface after rain and deposited after water evaporates.

Question 20

How are animals (e.g. camel) adapted to the desert?

Answer 20

1. Long eyelashes to prevent sand entering eyes.
2. Sandy coat to reflect light.
3. Nostrils can close so that sand is prevented from entering.
4. Animals often nocturnal and hunt in night.
5. Hump stores fat that can be metabolised for energy, which releases water.
6. Specially adapted organs can function with little water.
7. Body temperature of a camel can fluctuate, meaning that sweating happens less often.
8. Leathery pads on interior of knees protects against the hot sand when sitting.

Question 21

What are the opportunities deserts provide for humans?

Answer 21

1. Believed to hide large oil and gas reserves, however, drilling and transporting workers there will be difficult (N.B. transporting fuel large distances will also cause pollution).
2. Sunlight in desert and space means that there is potential for solar power, which can be exported.
3. Opportunities for mining, however, transportation will cause pollution, hard to transport workers, opencast mining causes visual pollution and is dangerous.
4. Opportunities for ecotourism, with interesting ecosystem and environment, which benefits local communities and funds conservation efforts. However, tyre marks ruins the appearance of dunes, and also does damage to vegetation by undermining the stability of the soil.