Monsoon in Pakistan free essay sample

Monsoon originates from Indian Ocean and Arabian Sea and then it travels to Indian Subcontinent. 7. Monsoon Path. Due to pressure difference over land and ocean winds start to blow from Southern Oceans to northern land. Under the influence of pressure gradient force and geostraphic force ultimately taking a South West direction. The phenomenon of monsoon is similar to that of sea breeze but it occurs on a very large scale. These South West moisture laden winds due to the southward protruding kink of India are then divided into two currents:- a. The Arabian Sea Current. These winds enter India from south west of India.The first area where monsoon strikes India is Kerala district (Western Ghats) and goes till central India conceding intense rains. b. The Bay of Bengal Current. These winds go to bay of Bangal and from there it enters Bangladesh and India. After blowing to North, it is stopped by the great Hamalayas from blowing it further north. We will write a custom essay sample on Monsoon in Pakistan or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Here these winds and the Arabian Sea winds join and blow to west resulting in monsoon in Pakistan. 8. Trigger Actions. Monsoon winds by them selves are not capable to give any precipitation. They need to be lifted up by some trigger actions to form clouds.Once lifted, they produce huge heap type clouds (Cumulus and cumulonimbus) with lots of moisture in them. Trigger actions are: a. Orographic Uplift. The marked influence of orography on monsoon precipitation pattern may be observed on Western Ghats, where a mountain range of 6000 ft – 7000 ft uplifts the moisture laden Arabian Sea current to sufficient height, required for condensation, and give plenty of rain fall on the wind ward side of Western Ghats. Now some portion of same current also reach the Thar Desert and Karachi but they get very rare rains because there is no Orographic uplifting there.The North and North Eastern parts of Pakistan Punjab (up to Rawalpindi / Islamabad) also get monsoon precipitation due to orography of the Himalayas and Hindu Kush ranges. b. Convection. As these moisture laden winds blow over the hot surface they become warm themselves, so as a result they start to rise up to form individual heap clouds. It is a common observation in summers that cumulus clouds are formed in the noon which grow with surface heating and ultimately turn in to CBs to give thunder storms in the afternoon. These clouds gradually dissipate in the evening due to fall of temperature. . Wind Convergence. Some times local convergence of winds takes place, which up lifts the air sufficiently to form Convective clouds (Cumulus and Cumulonimbus). This local convergence, not being associated with any pressure system, may occur at any time during the day or night and give precipitation. It is very difficult to forecast this phenomenon. 9. Factors Controlling Movement of Monsoon a. Low Over Tibet Plateau. The Tibet plateau is a 200 KM long, 1000 Km wide block of high ground over which a low forms in summers. This plays a major role in the rapid arrival of monsoon in June.In a simplified way it can be said that Tibetan low is responsible for sucking in the monsoon to deeper (Northern) parts of subcontinent. b. Himalayas. Had it not been for East / West belt of Himalayas and Hindukush ranges the monsoon would have never reached Pakistan. These ranges play two roles, not only they deflect the currents towards Pakistan but also provide Orographic up lift due to which Pakistan’s northern parts get monsoon precipitation. c. Sub Tropical Jet Stream. This is a westerly jet stream between 28 33 degree North latitudes, found at approximately 30,000 feet. Although in April/ May monsoon winds are established but their northward surge is hindered by this jet stream, however in early June this jet stream moves northward to 40 degree North latitude so only then winds travel to northern parts of subcontinent. 10. Time Span of Monsoon. The monsoon season is divided into three periods:- a. Pre monsoon Period. This is an interim period from April till June. A low or a secondary low develops over Balochistan. Due to surface heating temperatures all over the country rise and pressures fall. The atmosphere becomes unstable and thunderstorms occur frequently.The activity is more frequent in the Northern and Western parts of the country with dust storm in the Southern parts. Temperature increases to 21 to 37 degree Celsius in the North and 45 to 50 degree Celsius in the plains. (1)Monthly Climatic Conditions (a)April. Rain/ thunderstorms are frequent, particularly in the northern parts of the country. Few dust storms also occur in this month. (b)May. Temperatures increase all over the country. Dust storms are quite frequent, thunderstorm and rains also occur. Visibility associated with dust storm reduces considerably.There are number of occasions when the visibility is less than 500 meters. On some occasions visibility is reduced to less than 100 Meters. (c)June. It is the period of maximum instability. Frequency of dust storms is more. Poor visibility, associated with dust in suspension (DIS) prevails over the plains of Sind, Punjab and Balochistan. Maximum temperatures are seen in this month. b. Mosoon Period. This is a period from July to September. The activity of hail and thunderstorm is more over the hills in the northern and western areas whereas the dust storms are more pronounced over the plains of Punjab, Sind and Balochistan.The average rainfall during this period in the northern parts ranges between 25 to 75 millimeter and in the southern parts 05 to 25 millimeters. (1)Monthly Climatic Conditions (a)July. Sialkot is the first district to receive monsoon and is followed by Gujranwala, Lahore and Rawalpindi divisions. Severe thundery activity, accompanied by rain, is a normal feature. The visibility remains 6 to 10 km, except during rain, when it may fall to less than 2 km. (b)August. This is the month of intense rainfall, particularly, in the upper parts of Punjab. Water level rises in the rivers and frequently floods occur.Visibility remains 5 to 7 km. (c)September. Monsoon starts to withdraw during this month. Frequency of rainfall decreases. Visibility remains 5 to 7 km. c. Post Monsoon Period. Post monsoon period is the driest of all the seasons. By this time monsoon has withdrawn completely. While the westerly waves are moving further north of Pakistan mostly along the central Asian States. Prolonged dry spell with some isolated rains over the northern areas is the common characteristic of this period. (1)Monthly Climatic Conditions (a)October. This month generally marks the end of the monsoon in Pakistan. Fair weather generally prevails.There are a few occasions of thunderstorm in the northern parts of the country. Visibility is often poor in the morning due to smoke haze/ dust. (b)November. Weather is generally good though the occasions of poor visibility due to dust or smoke haze are more than October. 11. Flying Hazards. Effects of monsoon on flying are:- a. Beware of sudden local development which can take place any where and at any time. Must check weather forecast before commencement of flying. b. Turbulence tends to increase and if severe, may make control of the aircraft difficult. Altimeter may give erroneous readings and gyro-operated flying instruments may topple. . Lightning may make small holes in the aircraft and cause false magnetic compass readings. Do not fly in 20 nautical miles radius of thunderstorm. d. Heavy hail may cause structural damage. Do not fly when rain or hail is forecasted. Do not park aircrafts in open. e. Ice formation in cumulonimbus clouds may be severe though usually short-lived and normal icing condition such as airframe and engine icing may occur. Cumulonimbus clouds must be avoided. f. Severe turbulence below/ within clouds and in the vicinity of cumulonimbus clouds. g. Sharp pressure change may occur. Must check and apply QNH before landing. h.Overcast conditions with low and medium clouds. Must get weather forecast specially the cloud base and radar picture for precipitation. i. Mixture setting gets disturbed, and if not adjusted can lead to engine quital. 12. Conclusion. After having studied the phenomenon of Monsoon in Pakistan, you all must be clear about its development, travel and weather conditions during monsoon. Its not only in Rahwali but after you all graduate from this place wherever you go must keep in mind hazards associated with monsoon. Never take chance with weather in flying as it might prove to be dangerous/ hazardous. Fly safe and best of luck.