Grade 11 Term 2 🌍 (the atmosphere) Flashcards
What is the difference between weather and climate?
Weather: up to a week
Climate: over 30 years
What climate does Stellenbosch experience?
Mediterranean climate
What air movements are associated with HP and LP ?
HP: subsidence
LP: convergence
What are the 3 main divisions of climate regions?
Tropical climate region
Semi-desert climate regions
Humid mid-latitude
What are the divisions of the tropical climate region?
Equatorial climate region (tropical humid)
Savanna climate region (tropical wet and dry)
What are the divisions of semi-desert and dryland climate regions?
Semi-desert climate region
Desert climate region
What are the divisions of humid mid-latitude
Mediterranean climate region
Highveld climate region
Humid subtropical climate region
Describe the climate in an equatorial climate region
Constant high temperatures. (Annual temperature range is less than the daily variation)
High amount of cloud cover
Rainfall heavy all year. Mostly convectional (thunder and lightning in afternoons)
Describe the climate in a savanna climate region
High temperatures.
Heavy summer rainfall (mostly convectional)
Dry winter (less sunlight)
Describe the climate in a semi-desert climate region
Very hot summers (max temp over 32 C)
Cold, dry winters
Low, unreliable summer rainfall
High evapotranspiration levels
Describe the climate in a desert climate region
Extremely high temperatures in summer. Warm winters.
Low rainfall
Low humidity
Describe the climate in a Mediterranean climate region
Warm to hot summers
Mild to cool winters
Dry summers, wet winters (mainly cyclonic rain)
Generally low humidity
Describe the climate in a highveld climate region
Dry, sunny winters. Rapid heat loss. Temperature inversions occur at night.
Summer- convectional rainfall with thunderstorms are common, followed by rapid clearing
Describe the climate in a humid subtropical climate region
Hot summers
Cooler winters
High summer rainfall
(Cooler than savanna)
Give an example of a city in an equatorial climate region
Barumbu, Zaire
Give an example of a city in a savanna climate region
Accra, Republic of Ghana
Give an example of a city in a semi-desert climate region
Gao, Mali
Give an example of a city in a desert climate region
Swakopmund, Namibia
Give an example of a city in a Mediterranean climate region
Algiers, Algeria
Give an example of a city in a highveld climate region
Johannesburg, South Africa
Give an example of a city in a humid subtropical climate region
Durban👣
Know ocean currents
🌺
How does latitude affect climate?
Places close to the equator are hotter because the sun’s rays are more direct and concentrated. More convection rainfall due to hot air rising, cooling and condensing.
What is temperature inversion?
Layer of cold air near the ground with warmer air above
Why do temperatures decrease with altitude?
There is less air to absorb heat radiated by the earth
Give an example of a part of Africa on the high-lying plateau that has lower temperatures because it’s at a higher altitude.
The Ethiopian highlands
Give examples of parts of Africa that lie on the subtropical high pressure belts
The Sahara and Kalahari deserts
Why is the Sahara desert the largest desert in the world?
On the Tropic of Cancer
Permanent high pressure system
Rain shadow by Atlas Mountains
When does the ITCZ move south and north of the equator?
South when Southern Hemisphere experiences summer
North when the Northern hemisphere experiences summer
Where do westerly winds and polar easterlies converge?
At the sub-polar low pressure belt
What factors affect Africa’s climate regions?
Latitude
Altitude
Convergence and subsidence
The ocean
What effect does the ocean have on climate?
The ocean moderates temperature and causes moist air
What is the Namib Desert a result of?
The cold Benguela
What do we call inland and coastal climates?
Continental climate 🌵
Maritime climate 🐚
Where will the ITCZ lie in July?
On the Tropic of Cancer
because it’s summer in the Northern Hemisphere
Along which pressure belt is there frontal rain?
The subtropical high pressure belt
Know how to draw and label a cross-section of Southern Africa
(Orange arrow)
Labels: Coastal plain, escarpment, plateau, West/ East coast, Indian/ Atlantic Ocean
🌺
Justify why Zürich is in the Northern Hemisphere if the highest temperatures are in June/July.
The Northern Hemisphere experiences Summer in June/July as the sun’s direct rays shine on the Tropic of Cancer during this time.
Justify why Zürich is in the Northern Hemisphere if the lowest temperatures are in December/January.
During December/January temperatures will be lower in the Northern Hemisphere as the sun’s direct rays move South (because of the tilt of the axis)
Why is there often a lapse between the peak temperature and the peak rainfall period?
With convectional rainfall it sometimes takes a while for the earth to heat up before evaporation occurs, so the peak rainfall period occurs after the highest temperature.
What is desertification ?
The process by which once fertile land becomes infertile.
What is a dryland?
An ecosystem characterised by a relative lack of water.
What is a drought?
An extended period of deficient rainfall relative to the statistical average over a number of years for a region.
What are the 4 dryland subtypes and their aridity indexes?
Hyper-arid environments (AI < 0,05)
Arid areas (0,05 < AI < 0,2)
Semi-arid areas (0,2 < AI < 0,5)
Dry subhumid areas (0,5 < AI < 0,65)
Define aridity index
Measures how dry an area is
What do dryland ecosystems include? Name at least 4 (of the 7)
Cultivated lands, scrublands, shrublands, grasslands, savannas, semi-deserts, true deserts
What is the difference between aridity and desertification? (Which drought is often linked to)
Aridity is a permanent and natural condition.
Desertification happens when human activity degrades ecosystems.
What are the 4 types of drought?
Meteorological drought
Agricultural drought
Hydrological drought
Socio-economic drought
What is a meteorological drought?
When there is a prolonged period of rainfall below the regional average.
What is an agricultural drought?
When shortages of precipitation and soil moisture affect crop yields.
What is a hydrological drought?
When water reserves fall below an established average
What is a socio-economic drought?
When reduced water supplies result in the inability to address social, economic and environmental demands.
What is the Sahel region?
A belt of grasslands south of the Sahara and along the central east coast.
The transition region between the Sahara desert and wetter equatorial regions.
What causes drought?
Mainly changing weather patterns.
Made worse by human activities, e.g. deforestation, overgrazing and poor cropping methods.
Name 4 examples of changing weather patterns
Excessive build-up of heat on the earth’s surface
High pressure systems becoming more common
Reduced cloud cover leading to great evaporation rates
Winds carrying continental air masses with reduced water content, rather than moist oceanic air masses
What are the short term effects of droughts? (7)
Stock-losses, failed harvests, falling production and food shortages. (Living cost increases)
Bushfires and dust storms.
Less tourism
Wells dry up
Hydro-electric plants may stop operating.
Water restrictions
Increased health risks
What is a land’s carrying capacity?
Its ability to support animals and people
What are the long term effects of drought?
8
Vulnerability of ecosystems and people.
Increased evaporation from water sources.
Ground subsides if the water-table drops.
Lower water quality.
Toxic algae outbreaks.
Loss in species diversity of plants and animals.
People forced to migrate.
Increased conflict over commodities, fertile land and water sources.
What can reduce the carrying capacity of land?
Overgrazing
What is land degradation ?
A process in which drylands lose their productive capacity
What are the 8 land use patterns and practices that contribute to desertification?
Farming in fragile areas Poor agricultural practices Farming of average land (not given time to replenish itself) Salt build-up Deforestation Improper soil-moisture management Erosion Surface mining (without land reclamation)
Name two factors that cause desertification
Climatic processes and human activities
What are the direct factors causing desertification?
Climate-related processes like global climate change
What are the indirect factors causing desertification?
Increasing human population
Lack of supportive infrastructure
Policies leading to unsustainable use of resources
Removal of international trade barriers
How does desertification effect the vulnerability of people and the environment?
(5 steps)
Agricultural reduced/ unpredictable Food security threatened (Desperate poor people over-exploit natural resources) Individualism and conflict People migrate Economies weaken
What positive changes can desertification bring?
Women can demand greater ease of access to land (men seeking work elsewhere)
Communities learn how to rehabilitate and manage land sustainably
Governments improve policies
What are the global consequences of desertification?
4
Global carbon cycle influenced
Biodiversity reduced
Reduced fresh water reserves
Underground fossil water reserves exploited
What can people do to manage the risk of drought and desertification?
(4)
Mitigation (reduce the intensity of the disaster)
Be prepared
Predict using climate and weather monitoring
Create early warning systems
What can people do to manage the crisis of drought and desertification?
(4)
Do an impact assessment
Find ways to cope
Respond as effectively as possible to the effects
Rebuild
What is orographic uplift?
An air mass that is forced up over rising terrain and cools adiabatically. This causes the humidity to increase, creating clouds.
