GEOGRAPHY Flashcards
What are the three causes of drought?
+examples
Human (Three Gorges Dam, China)
Meteorlogical (New South Wales, Australia)
Hydrological (Aquifers)
What is human drought?
Dams on rivers -make river levels drop further downstream.
Uses in agriculture -takes water from rivers and lakes
Deforestation -less trees to absorb rainfall and reintroduce it to the water cycle, and global warming effects
What is meteorological drought?
When there is a change in the weather patterns. -jet streams divert low pressure areas off their usual path
What is hydrological drought?
The impacts of low ground water and the water cycle
Effects of drought.
- Ill health due to poor water quality and supply of water
- Safety risk due to fires and dust storms
- Wildlife may migrate away from the area
- Food prices increase as production decreases
- Mass unemployment
California case study. (Developed)
- State of emergency in Jan 2014
- Popular destination for foreign and domestic tourists
- Caused by agriculture and diverting rivers
- desertified soil
- worst drought in 1200 years
- 5000 people without water
- £12,000 water bills to some farmers
- Aquifers lose all their water for agriculture
- California aims to have 100% renewable energy by 2045
- more scientists hired to research into this.
Ethiopia case study. (Developing)
- Been struggling with drought since the 1980s
- Usually receives 2 periods of rainfall a year but these have become shorter and more delayed since the 1980s
- Likely cause of this is the Indian ocean heating up causing there to be less rainfall
- Dry air moves westward and descends over East-Africa
- Agriculture is affected especially for subsistence farmers who farm for themselves and their family
- 85% live in the countryside and only 57% have access to an improved water source
- cholera, typhoid and diphtheria are prominent and lack of medical care can cause these to be fatal.
- ‘Live Aid’ was a charity set up in the 1980s to try help with this
What happens in areas of high pressure?
Air descends and there is little rainfall.
What happens in areas of low pressure?
Air rises and there is more rainfall.
Typhoon Haiyan case study
- Formed on the 2nd November 2013
- Rated 5 on the Saffir-Simpson Scale
- 6000+ declared dead
- Cut off communication
- Homelessness
- 2 Billion USD in damages
- Chemical leaks and oil spills
- Placed under ‘national calamity’
Eruption Theory
Volcanic eruptions produce ash and block solar rays decreasing global temperatures
(e.g the little ice age)
(5-10 years)
Sunspots
Black areas on the sun’s surface that fires more solar energy towards earth than normal increasing global temperatures, (e.g the medieval warm)
(500 years)
Milankovitch cycles
The earth’s orbit can change from being more circular to more of an ellipse.
The axial tilt cand change from being upright and on its side.
These change the amount of sunlight the earth receives and change over tens of thousands of years.
Tropical storms
They form close to the equator (0 degrees latitude) and travel in the direction of the prevailing winds.
In the northern hemisphere they spin clockwise and in the southern hemisphere they spin anti-clockwise.
Anywhere from 5-30 degrees latitude in the hadley cell.
Atmospheric Circulation
Hadley - 0-30
Ferrel - 30-60
Polar - 60-90
These cells work by hot air rising and maintaining a height until it starts to cool and descend and this all happens in different sections on different areas of latitude.
