2. Weather and Climate
Weather
Weather refers to the atmospheric conditions
(temperature, rainfall, humidity and pressure) of any
place for a short period of time. It is often localized.
Climate
Climate is a generalization of the day to day weather
conditions over a long period of time, usually thirty
years.
3. Climatic Zones of Pakistan
Pakistan extends from 24° N to about 37° N.
Its western border lies close to 62°E, its northeastern
border extends to about 74○E, while Kashmir extends
to 80° E.
To the north of West Pakistan lie the lofty
mountainous ranges of the Pir Panjal, the greater
Himalaya and the Karakoram ranges.
4. CONTD
The Sulaiman mountains are in the northwest, while
Koh-i-Taftan and then lower ranges in continuation
of the Namak-sar desert beyond them lie to the west,
between Pakistan and Iran.
These physical features have a great bearing on the
climatology of the area in so much as they not only
modify rainfall and temperature pattern of West
Pakistan, but also greatly influence the general
circulation of the atmosphere in the Sub-continent.
5. CONTD
Pakistan's topographical features range
from lofty mountains in the north to the
coastal plains in the south.
Climatic divisions of Pakistan are:
A.Highland climate
B.Lowland climate
C.Coastal climate
D.Arid climate
6.
7. CONTD
Zone A indicates highland climate prevailing over
northern, north-western and western mountains.
Zone B has lowland climate, which prevails over the
whole of the Indus Plain.
Zone C has coastal climate experienced by the
Makran Coast, Karachi Coast and Indus Delta till the
Rann of Kutch.
Zone D has arid climate and includes the south-eastern
desert and south-western part of Balochistan.
8. A division of climatic zones does not imply exactly
the same conditions throughout the zone.
There are great variations in rainfall, temperature,
humidity etc in the same climatic zone.
For example, northern highlands and western
highlands fall in the same climatic zone but the
amount and seasonal distribution of rainfall is
different.
Murree and Hazara hills experience more than 1500
mm average annual rainfall mostly during the
summer season, whereas in the western highlands
Quetta and Pishin receive 250 - 500 mm average
annual rainfall.
9. A. Highland Climate
This region includes northern, north-western and
western highlands.
The winter are long, cold and snowy and the
summers remain short and mild.
In mountainous areas rainfall is normally associated
with altitude.
The height of the northern mountains range from
2000 meters to above 8000 meters, while in the
western mountains the height is approximately from
1000 to over 4000 meters.
10. CONTD
Rainfall in the northern mountains is the highest in
the highland zone.
The western mountains experience less rainfall.
From south of Kohat and Waziristan rainfall
decreases and occurs during the winter season.
To the north-west, Gilgit and Chitral also experience
low rainfall, as they are rainshadow areas.
11. CONTD
The temperature conditions also vary from north
to west depending on the altitude.
Summers are short, mild and wet in the northern
mountains but dry and warm in the western
mountains.
12. B. Lowland Climate (Semi-arid to arid)
This region includes the whole of the Indus Plain
except the coastal areas.
Most parts of the Indus Plain lie at the western
end of the tropical monsoon zone.
It has arid and extreme climate with hot
summers, cool winters and summer monsoon
rainfall.
The amount of rainfall differs from north to
south.
13. CONTD
The foothills of the northern mountains and
Potwar Plateau are wetter than the Indus Plain,
and also receive rainfall from Western
Depressions.
Thunderstorms are also common in the north
and north-west of the Indus Plain.
The southern Upper Indus Plain and the whole of
the Lower Indus Plain have much less rainfall and
spells of very high temperature.
14. C. Coastal Climate:
The region includes the southern coastal
strip comprising of the Indus Delta, Karachi
and the whole of the Makran coast.
The climate is dominated by sea breezes
throughout the year.
The maritime influence keeps the daily
range of temperature low.
16. CONTD
This shows that the influence of sea is left mainly
through the prevailing winds.
The temperature at sea and on land is different owing
to unequal heating of land and water by the sun.
Land and water absorb the sun's heat at different
rates, and also radiate or lose it at different speeds.
In summer the land heats up, while the ocean
remains comparatively cool.
17. CONTD
In summer the land heats up, while the ocean remains
comparatively cool.
In winter the land loses heat quickly and becomes cold
while the ocean is much warmer and keeps its warmth
for a long time.
The humidity level is moderately high, exceeding more
than 50% from April to September.
18. CONTD
Mean monthly temperature is 32○C, and May, June and
October are the hottest months.
During October dry winds from the south-eastern desert
dominate the climate.
Rainfall is scanty throughout the year.
From Karachi up to the Rann of Kutch, the coast
experiences most of its rainfall during the monsoon
season, while on the Makran coast it falls in winter.
19. D. Arid Climate:
An arid climate is experienced in south-western
Balochistan and the south-eastern desert.
It is markedly dry and hot.
Hot dusty winds prevail almost continuously from
mid-May to mid-September.
Most of the scanty rainfall in south-western
Balochistan takes place during the winter season.
In the south-eastern desert, summer monsoons bring
little rainfall.
Extreme heat, dryness and dust storms are the main
features of this arid climate.