EQ2-5.4 droughts

Question 1

Define a drought?

Answer 1

Droughts occur when there is a water deficit in a particular area over a period of time, compared to the average rainfall for that area.

Question 2

Describe the first stage of a drought

Answer 2

Meteorological drought.

• Precipitation deficiency occurs- In amount, intensity and frequency.
• high temperatures, high winds, low relative humidity, greater sunshine and less cloud cover
• increased evapotranspiration
• reduced infiltration, runoff, deep percolation and ground water recharge

Question 3

Describe the second stage of a drought?

Answer 3

Agricultural drought.

• soil water deficiency
• plant water stress, reduced biomass and yield

Question 4

Describe the third stage of a drought?

Answer 4

The hydrological drought.

-reduced stem flow, inflow to reservoirs , lakes and ponds, reduced wetlands and wildlife habitat

Question 5

Describe the fourth stage of a drought.

Answer 5

Famine.

A widespread failure of agricultural systems over a prolonged period of time leads to a food shortage and famines with other social, economic and environmental impacts.

Question 6

What are the four stages of drought, in order.

Answer 6

Meteorological, agricultural, hydrological and famine

Question 7

What are the physical factors which can affect droughts

Answer 7

Global atmospheric circulation.
The ITCZ inter tropical convergence zone
Mid latitude blocking cyclones
El Niño and La Niña

Question 8

How does global atmospheric circulation affect weather?

Answer 8

High pressure zones cause little to no rain, they are formed 30 degrees north and south of the equator
Low pressure zones cause lots of rain and cloud cover, they are formed 0, 60 and 90 degrees North and south of the equator

Question 9

What is the itcz? How does the intercontinental convergence zone cause drought?

Answer 9

The ITCZ is a belt of low atmospheric pressure located around the equator. At the itcz the air rises as a result of intense heating by the suns energy.It therefore causes a wet season when it arrives and a dry season when it leaves
This can be altered by areas of high pressure and it can divert the ITCZ to other areas altering the location which revive drought or flood

Question 10

How do mid-latitude blocking cyclones cause drought?

Answer 10

High pressure deflects low pressure meaning it prevents rain in areas. Low pressure can also be sandwiched between two high pressure fronts causing an atmospheric river which can direct moist area at a wet area causing flooding or deflect moist air form an arid location