9.causes of droughts
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TRANSCRIPT
The Causes and Effects of Drought
LO: To understand the causes of anti-cyclonic weather and the global distribution of droughts.
Starter Activity:Write down all the ways in which we
use water every day.Which ones could
you not do without?Which ones are
easier to cut down on?
What is a drought?• Look at the pictures and come up with a
definition of your own.
A lack or of for an unusually
period of , involving less than the
usual over 3 months
A lack or shortage of water for an unusually long period of time, involving 50% less than the usual rainfall over 3 months
A good definition for drought
A drought is
A reduction in precipitation over an extendedperiod of time. (lack of rainfall)
‘Effective precipitation’
The difference between actual precipitation andevapo-transpiration.
What’s different about a drought compared to a hurricane, earthquake or volcano?
(apart from the obvious!)
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec0
50
100
150
200
250
300
350
400
450
500Rainfall in Southern Spain
Months
Rain
fall
or e
vapo
tran
spir
ation
in m
mEvapotranspirationRainfall Q: Explain which months Spain is at risk
of severe drought.
Droughts. So where do you think?
Where do the droughts occur?
Arid Semi Arid
http://drought.mssl.ucl.ac.uk/drought.html?map=%2Fwww%2Fdrought%2Fweb_pages%2Fdrought.map&program=%2Fcgi-bin%2Fmapserv&root=%2Fwww%2Fdrought2%2F&map_web_imagepath=%2Ftmp%2F&map_web_imageurl=%2Ftmp%2F&map_web_template=%2Fdrought.html
Some areas are more at risk than others...
Arid + High Density = High Risk
Use the atlas to gather population density data and then write a description of the distribution of droughts globally considering the potential risk to the areas below. (Arid + High Density = High Risk)
Arid Semi Arid
North America
South America
Africa
Asia
Oceania
How might these factors affect the severity of a drought?
Mix and match
• Complete the sheet to show all the different factors that affect the severity of drought.
• Extension question: how might the effects of drought be different in an LEDC and an MEDC?