RAINFALL IN

PAKISTAN

Rainfall is a term used to refer to water falling in drops after condensation of the atmospheric vapour. The term is also used to refer to the quantity of precipitation falling in an area within a given period of time.

Rainfall

Sources of rainfall inPakistan:• Monsoon winds• The Western Depression• Convectional Currents• Relief rainfall• Tropical cyclones

Monsoon windsMonsoon winds are seasonal winds which blow during summer and winter. The summer winds are called South-west monsoons and the winter winds are called North-east monsoons.

South-west monsoon:South-west monsoon are giant sea breezes

which bring rainfall. The rains began when the ocean are less heated and land is more heated. The air from the land rises developing a low pressure and it attracts the cool air causing heavy rainfall. The southwestern summer monsoons occur from June through September

North-east monsoons:North-east monsoons blow from the land

towards the sea.

Monsoon and PakistanPakistan receives the tail end of the monsoon.Which enter the Pakistan after crossing India they usually reach Pakistan in early July and continue to September. Since the monsoon come into Pakistanfrom the East. The eastern part receive more rainfall in the monsoon,the main monsoon enter NorthernPunjab while the secondarySouthern Punjab and Sindh.The highest rainfall during the monsoon season as receive by Murree that is 850mm.

Western depressionThe western depression winds blow from the Mediterranean sea in the winter and after passing through Iran and Afghanistan they enter in the western area of Pakistan and cause rainfall.

The Western depression enter Pakistan from the west afterpassing through Iran and Afghanistan, most of their moisture islost on their long land journey. Therefore they bring a smallamount of rainfall to Pakistan in spite of this the western partsof western highlands receive more rainfall from the westerndepression then from other sources.Because of Western Depression Northern Punjab,the hilly areas of kpk and Northern Baluchistan receive 125 to 250mm of rainfall. Sindh is the driest area where in most parts the rainfall isless then 25mm.Rain fall from western depression begins in December and

continues up to March.

Western depression and Pakistan

Convectional currentsThis 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 resultsin rainfall in differentareas in summer.

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

Convectional currents and

Pakistan

Relief rainfallRelief rain usually takes place around  coastal areas where a fleet of hills runs along to the coast. When wet onshore wind from the sea meet a mountain, hill and barrier, it is forced to rise along the slope and cools. When the air temperature falls to its dew point, water vapor condenses to form clouds. When the clouds can no longer hold the water droplets, relief rain begins to fall on the windward slope of the mountain.

Relief rainfall and PakistanCities like Murree and Kakul continually receive rainfall due to this while Gilgit and Chitral do not as they fall in the rain shadow areas.

Tropical cyclonesA tropical cyclone is a rapidly-rotating storm system characterized by a low-pressure center, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain,can cause a lot of destruction.

Tropical cyclones and PakistanThey originate in Arabian Sea quite often but rarely reach the coast of Pakistan. Therefore, this source of rainfall is totally unreliable.