Rainfall in Pakistan Arid Areas Seasonal Rains Kinds of Rains

1. Rainfall

2. Not equally distributed in Pakistan
Small area of northern Punjab & parts of KPK enjoy
humid conditions
Evapotranspiration
Evaporation is when liquid turns into vapour & the loss
of water from soil
Transpiration is the release of water vapour through
plants

3. 2 types of evapotranspiration
1. Potential Evapotranspiration
Maximum of vapour loss from soils & plants at
a given temperature
Higher temperature means higher
evapotranspiration
2. Actual evapotranspiration
Actual water loss
Depends on the amount of water in soil &
plants

4. Types of Rainfall
1. Conventional Rainfall
Surface air heated up and rises up.
žCools down in higher altitude.
žFall down as rain.
žAccompanies with thunder and lightning.
žResultant clouds are cumulonimbus type.

5. 2. Orographic Rainfall
Found on the windward sides of mountain ranges lying
across the path of
the prevailing terrestrial winds.
The leeward sides of the mountains is the rain shadow
region.

6. Saturated air from sea
Hits the mountains
Air cools in high altitude.
Falls as rain in the mountain slope.

7. 3. Cyclonic/Frontal Rainfall
Occurs along the frontal zones of convergence.
Meeting of hot and cold air
Cold air push up the hot air
As altitude increase the hot air cool downs
Condensation happens
Rain occurs.

9. Rainfall Areas in Pakistan
1. Arid Areas
Large part of Pakistan is arid
Whole Sindh, southern Punjab & Southern
Baluchistan
250 mm rain annually
Farming through irrigation
2. Semi-Arid Areas
Northern Punjab, Northern Baluchistan & major
part of KPK
250-750 mm annual rainfall
Irrigation practised extensively

10. 3. Humid Areas
Small area of Pakistan is humid
Northern strip of Punjab, adjoining KPK &
around Parachinar
Rainfall exceeds 750mm

11. Seasonal Distribution of Rainfall
1. Monsoon Rainfall (July-September)
Pakistan receives tail end of monsoon
Monsoon winds from India reach Pakistan in July
& can last up to September
Eastern Pakistan receives more monsoon rainfall
From Sargodha southward rainfall drops to less
than 250mm
From Sahiwal it drop down to less than 125mm
Higher rainfall is recorded in Murree 813mm &
lowest Nok Kundi 2.5 mm

15. 2. Rainfall from Western Disturbances
Enter from west through Afghanistan & Iran
Bring small amount of rain
From December to March
Since it coincides with winter so precipitation at
higher altitudes happens as snowfall
In Murree, Dir, Saidu Sharif 500mm
Northern Punjab, KPK & Baluchistan 125-250
Sindh…
3. Rainfall from Thunderstorms
During driest seasons (October & November)

17. Convectional Currents
Happens when hot air rises from the hot land into the air.
This air is high in moisture, and causes a lot of
condensation when it reaches the atmosphere.
This condensation results in rainfall in different areas in
summer

18. Convectional currents cause some degree of
rainfall in Pakistan during the summer months.
 This condensation results in rainfall in the
northern and north-Westren parts of Pakistan in
the summer.
The southern parts of Pakistan are deprived from
convectional currents due to a temperature
inversion layer