Desert Flashcards
Where is hot desert located and Saraha desert?
Hot desert are found near the tropics of cancer and Capricorn, north or south of the equator.
In North Africa (Saraha)
Desert temperatures
Desert have extreme temperatures during the day the temperature may reach 50c and the lowest temp is 22c. Desert usually have less than 250mm rainfall per year the rain can be unreliable
Cactus plant adaptation
Thick waxy skin to reduce loss of water and reflect heat
Large, fleshy stem to store water
Thorns and thin spiky or glossy leaves to reduce water loss
Spikes protect Cacti from animal wishing to use the store water
plant lie dormant for years till rainfall.
How do hot desert form?
At the equator air rises
some condenses and cool leading cloud+ rainfall and creation of rainforest
Some air continues to rises 17km above ground is drier it sinks (Hadley cells)
This leads to the creation of desert
Dry to the wind circulation. Called the cold wind candy blows the air to the equator and rises as the air rises, water vapour cools and condenses dry air keeps rising until 17km high. Then they are blown to the north and south at the Tropic of Cancer, these air hot and sinks causing the Hadley cell effect as a result Sahara is dry
Sahara is hot is because all the wet air condense at the equator when the dry air comes they will not condense into clouds this mean the sunlight can reach Sahara without clouds directly. Therefore the surface of Sahara will be heated quickly.
The latitude of Sahara is low. It is at the Tropic of Cancer which mean the sunlight will reach the surface at high angle all year round. This helps the sunlight heat up Sahara easily causing the hot climate
Plants adaptation
Plants adaptation
Small narrow leaves e.g Joshua tree
-> this reduces water that is lost through transpiration
Grow slow cuz not enough rain often store water in stem and leaves
Roots can be shallow or deep
-shallow to quickly or deep
-get water from underneath the ground
Plants have defines to protect that from herbivores
JOSHUA TREE
Needle like leaves to minimise the water loss and protect itself from animals trying to eat it . The tree leaves are coated with waxy resin which minimise water loss and taste horrible to animals trying to eat it
Animal adaptation
Birds cool by panting
- birds migrate
- food can be plentiful
- nutrients from desert in sea
Fennec fox
Large ear radiating heat away
Kangaroo rats
—> burrow
Nocturnal animals only come at
Camel adaptation
Thick fur on the top of the body for shade, thin fur elsewhere to allow heat loss
Large surface area to volume ration which maximise heat loss
Large feet to spread their weight on the sand
The ability to go without water for a long time- they lose very little through urination and sweating
A fatty hump which provides energy in times of food shortages
The ability to tolerate body temperature up to 42c
Slit like nostrils and two rows of eyelashes to help keep the sand out of their eyes
Explain why wind direction and distance from the sea are important
Desert and inland so wind dry by the time they reach them blow from land to sea
Explain how latitude and atmospheric pressure influence the characteristics of equatorial and hot desert climate
Desert is hot because the sun is over head
Equatorial climate doesn’t have season because the sun is overhead
Desert formation
Hot moist air rises into the atmosphere near the equator as the air rises it cools and drop moisture as heavy tropical rain. Some air continues to rise 17 km it air descend and warm up again . The descending air hinders the formation of clouds so very little rain falls on the ground Harley cells
Cold current contributes to the formation of coastal desert
Explain why a hot desert may form near mountains
Air mass rises of the mountain range
Air expands
Air mass cools
Condensation of water vapour
Saturation of air mass
Precipitation on mountain
Air descends
Heating of air mass at leeward side
No condensation takes place
Formation of Sahara
As the air leaves the equator , it rains away more moisture becoming more denser and slightly cooler until finally dry it air descends no cooling on the equator as high pressure .
Lack of clouds
Overhead sun
It also caused by the cold canary current , it reduces the relative humidity of air mass and wind that moves eastward from Atlantic Ocean . The cold current helps the desertification of Sahara desert
Dry to the wind circulation. Called the cold wind candy blows the air to the equator and rises as the air rises, water vapour cools and condenses dry air keeps rising until 17km high. Then they are blown to the north and south at the Tropic of Cancer, these air hot and sinks causing the Hadley cell effect as a result Sahara is dry
Sahara is hot is because all the wet air condense at the equator when the dry air comes they will not condense into clouds this mean the sunlight can reach Sahara without clouds directly. Therefore the surface of Sahara will be heated quickly.
The latitude of Sahara is low. It is at the Tropic of Cancer which mean the sunlight will reach the surface at high angle all year round. This helps the sunlight heat up Sahara easily causing the hot climate
Characteristics
Overhead sun
Clear skies
High pressure
Descending air
Little evaporation
No condensation
Rain shadow effect
Cold ocean current
Desert
High pressure
Low transpiration
Low condensation
High temperature
Cold current
Descending air
Over head sun
Lack of clouds
Physical causes (desertification)
Annual rainfall totals are gradually decreasing
Climate change and drought
Less vegetation means less water gets back into the atmosphere through transpiration
