Climate of Pakistan

Climate: Climate is the generalization of the day-to-day weather conditions over a long period of time,
normally 30 years.

Weather: Weather refers to the atmospheric conditions (temperature, humidity, rainfall and pressure)
of any place for a short period of time. It is often localized.

Humidity: Humidity is the amount of water vapours present in air.

Condensation: Condensation is the conversion of water vapours into liquid. Clouds are formed by
condensation of water.

Temperature Key

Temperature Description

40 C and above Very hot

31 C – 39 C Hot

21 C – 30 C Warm

10 C – 20 C Mild

3C–9C Cool

-5 C to -2 C Cold

-5 C and below Very Cold

Climatic Zones

 Highland Climate
 Lowland Climate
 Coastal Climate
 Arid Climate

Highland Climate: Northern Mountains

 Cold to very cold winters.

 Mild summers
 Rainfall in all seasons (mainly in form of snow in winter)
 Large daily range.

Western Mountains

 Cold winters
 Warm summers
 Winter rainfall
 Large daily range

Lowland Climate (UIP, LIP and Pothwar Plateau)

  Cool winters
 Hot summers
 Monsoon rainfall
 Aridity increases form north to south
 Large daily range.

Coastal Climate (Karachi Coast)

 Mild winters
 Warm summers
 Monsoon rainfall
 Tropical cyclones
 Short daily range (due to maritime influence)

Makran Coast

 Mild winters
 Warm summers
 Western Depressions (from Iran)
 Tropical Cyclones
 Short daily range

Arid Climate (Deserts e.g. Thar and Kharan)

 Mild winters
 Hot summers
 Extreme aridity due to little rainfall
 Large daily range
 Dust storms

Factors Influencing Temperatures

 Latitude
 Altitude
 Distance from sea.

Latitude / Angle of Sun

Temperature higher at or near the equator due to high angle of Sun.

As we move down or up the equator towards North or South Pole, Temperature decreases.

This is because rays spread over a larger area due to a low angle of Sun.

Altitude / Height of Land

 As height increases temperature decreases.

 Air is less dense so hold less heat as you go upwards.
 Heat radiated from surface decreases as altitude increases.
 Fall of 5 C for each 500m increase in height (in dry or arid air)
Distance from Sea

Maritime Influence
 Climate influenced by sea has low range of temperature between summer and winter.
 Places near coast are cooled by sea in summer and warmed in winter.
Continental Influence
 Land is not under sea influence i.e. are too far from sea.
 In these inland areas, temperature is high in summer as land heats up rapidly.
 In winter, land gives off heat rapidly and so locations experience colder winters.

Sources of Rainfall in Pakistan

 Monsoon winds
 Western depressions
 Convectional currents
 Tropical cyclones
 Relief rainfall

Monsoon winds

 Bay of Bengal
 Moisture bearing winds carrying rain.
 Blow from Bay of Bengal (East to West)
 After crossing Bangladesh and Northern India, the tail end of the winds enter Northern Pakistan/
Upper Indus Plain
 Move towards Northern areas due to low pressure there.
 Rise over land and cool
 Moisture condenses
 So clouds are formed therefore heavy rainfall.

Arabian Sea

 Some monsoon winds blow across south east Pakistan from the Arabian sea.
 These are weak winds that have little effect.
 However, sometimes, an overactive monsoon system brings heavy monsoon rainfall in Karachi.
 June – July

Causes of Monsoon Rainfall at Karachi

 Low pressure develops overland

 Draws in moisture bearing winds from high pressure area on the Arabian sea. Rise over land
 Cools
 Moisture condenses
 Clouds are formed so rainfall.

Importance of Monsoon Rainfall to People of Urban Areas

 Cooler, better working and living conditions due to pleasant climate.

 Fresher – less dust / air pollution, clean air.
  Water supply for drinking, factories, markets and gardens.

Q. Explain why the lack of monsoon rainfall in Southern Punjab and Sindh causes problems for
farmers.

 Poor crop growth

 Low profits/Income
 Little or no other sources of rainfall e.g. no Western depressions, relief rainfall etc.
 High evaporation, evapo-transpiration due to high temperature.
 Need for irrigation e.g. tube wells which expensive.
 Can be soil erosion / blowing.

Western Depressions

 They are low air pressure system which originates in Mediterranean Sea.
 They travel across Afghanistan and Iran and then reach Pakistan’s western Areas.
 Bring moisture.
 Rises over land
 Cooling causes condensation
 So, clouds are formed
 Rainfall occurs from December to March.
 Quetta receives most of its rainfall through western depression.

Advantages and Disadvantages of Winter Rainfall in Northern Pakistan

Advantages
 Fills reservoirs and rivers so more storage
 Water available for irrigation
 Water available for hydroelectric power generation – HEP
 Water for Barani crops
 Water for Rabi winter crops
 Lighter form of rain – can snow in
 Snow for tourism

Disadvantages

 May fall as snow so of little use as rivers lakes shall be frozen.

 Damage to environment – landslides and floods etc.
 Damage to roads – blockage and slippery
 Silt collects in reservoirs / dams.
 Difficulties meaning farmers should do transhumance.
 Or else livestock farming or crop farming cannot be practiced.

Convectional Currents

 At the start of summer due to high temperatures

 Moisture evaporates from rivers/lakes/vegetation etc.
 Moist air rises.
 Causing condensation
  Which causes rainfall, often as thunderstorms
 Northern and North Western areas often get this rainfall
 Mainly Peshawar and Rawalpindi
 April to June and September to November (same as tropical cyclones)

Tropical Cyclones

 These may bring few hours of very heavy rainfall with destructive winds to coastal areas
 Originate from Arabian Sea quite often but rarely reach coastal areas of Pakistan (Makran and
Sindh Coast)

Q. Name the violent storm that form over sea and that may affect Karachi.

Tropical Cyclones.

Q. In which months may these occur?

April to June

September to November

Q. Explain how storms such as these may affect industry and communication in urban areas? [6]

 Flooding/heavy rain + strong winds + lightning strikes

 Damage or closure of buildings, roads, bridges and airport
 Lack of deliveries to customers
 Loss of production as work stops
 Difficult for Labour get to work
 Lack of experts and investors as airports remain closed
 Loss of electricity as wires and poles are grounded
 Loss of telecommunications

Relief Rainfall

 Related to height of land

 It occurs where moist air moves up after striking a mountain side
 It is cooled on reaching a certain height
 Cooling causes condensation and precipitation on the ‘wind ward’ side.
 The leeward side (the other side of the mountain) receives sinking warm air and a dry rain
shadow area is normally formed.
 Areas having high altitude receive this rainfall e.g. Northern Mountains.

Feasibility of Improving water supply to farmers In Punjab and Sindh

Possibilities / In Favour
 Rainfall In the monsoon season can be stored
 Snow melt from mountains
 Indus river system brings water from highlands
 Can make more storage in reservoirs of dams and barrages.
 Can build more canals
 Can use ground water and therefore can build more tube wells.

Impossibilities / Against
 Cost of reservoirs / canals
 Cost of tube wells
 Lack of reservoir and barrages
 Indus Water Treaty limits supply – conflict with India over supply
 Lower water table restricts groundwater
 Cost of power supplies for pumps
 Other constraints e.g. education, wastage, conflict between users.

Effects of Climate on:

Highland Zones
 In Northern areas temperature falls below freezing point/very cold in winter which:
 Stops growth of trees; buries grass under snow
 Makes farming impossible
 Transhumance is also practiced
 Landslides and avalanches block roads
 People are forced to stay indoors … so cottage industry.

Lowland Zones
 Crops can be grown in both summer and winter due to warm / hot summers and cool
winters.
 Densely populated due to tolerable summer and winter temperature.
 Monsoon rainfall is suitable for Barani crops.
 Monsoon rainfall provides enough water to rivers or canals for irrigation.
 Floods destroy crops and lead to loss of lives
 Floods however replenishes the soil nutrients with alluvium.

Arid Zones
 Very hot and dry in summer (very low precipitation) so not ideal for cultivation.
 Or habitation.
 Nomadic lifestyle due to low rainfall
 Karez system is practiced due to high evapo-transpiration in Kharan desert. People wear
thick clothes to protect themselves from hot winds.
 Frequent dust storms make work difficult.

Hazards
Causes of Floods
Natural
 Melting of snow during summer
 Heavy rainfall (monsoon)
Human
  Cutting of trees on foothills increases surface runoff
 Failure to strengthen or heighten embankments of rivers.

Effects of Flooding
Positive
 Increases fertility of the land through fresh alluvium
 Floods also recharge ground water supply
 Reproduction, breeding and multiplication of inland fresh water fish.
Negative
 Farmers cannot practice agriculture until water drains away
 Loss of lives
 Destruction of crops
 Mud houses and huts may be severely damaged
 Spread of water borne diseases e.g. cholera
 Roads and bridges washed away
 Rehabilitation and reconstruction is expensive.

Precautions
 Planting trees on foothills to check the flow of running water.
 Enlarging river channel so that It can hold more water.
 Building embankments
 Building reservoirs on rivers to store water and control peak discharge
 Preventing building construction in areas where flooding is most likely
 Publicizing flood warnings through radio, TV etc.
 Timely evacuation of people from flooded areas

Drought Types
Permanent Droughts
Exists when crop cultivation is not possible without irrigation e.g. Thal
Seasonal Droughts
Areas with well-defined rainy and dry seasons.
Invisible Droughts
Is the result of water deficiency that reduces crop yield but is not severe enough to destroy
them.
Unpredictable Drought
Is the result of abnormally sudden shortage in rainfall due to no particular reason.
Effects of Droughts
 Shortage of water
 Shortage of grazing grounds
 Crops may fail
 May lead to food shortages
 More imports of wheat
 Loss of lives due to starvation and thirsts
 Loss of livestock
 Weak animals with low outputs
 Diseases e.g. of skin due to dryness
 More rural to urban migration
 May cause soil erosion / desertification
Solutions
 More reservoirs to store water
 Desalination of salty water to increase the amount of fresh water for agriculture etc.
 More plantation to reduce soil erosion
 And more moisture in air for rainfall
 Such seed should be sown which are drought resistant.