ANNUAL AND SEASONAL DISTRIBUTION OF SUNSHINE IN PAKISTAN 1931-1990

Saifullah Khan, Mahmood-Ul-Hasan, Muhammad Aslam Khan
Institute of Geography, Urban and Regional Planning, Disaster Management Center, University of Peshawar, KPK, Pakistan

Abstract

This paper on sunshine distribution of Pakistan is based on normal data derived from various meteorological stations over the period of sixty years (1930-1990). The research analyzes the sunshine distribution in Pakistan and its advantages in harnessing the solar energy in the entire country.
Sunshine brings radiant energy to the earth surface. The amount of bright sunshine is badly affected by cloudiness, humidity, air pollution, latitudinal and altitudinal location, physical relief, annual march of the sun, and length of day and night. Sunshine is also beneficial to mankind and vegetation cover. The rate of growth of plant is largely influenced by the amount of solar energy that plant receives. In long hours of summer sunshine, crops and vegetation grow rapidly and reach maturity in a short time span during a season. Some plants require short days (winter), while other needs long days (summer), but some are also indifferent to the length of daylight for flowering and photosynthesis. Excess and shortage in the degree of bright sunshine causes various diseases in plants as well as in animals. Therefore, moderate sunshine, practically, is essential for plants as well as human activities.
The country receives a considerable amount of sunshine during the year as a whole. The annual average sunshine of the country is 8hr/day. January has the lowest sunshine with 6.1hr/day, and June experiences the highest sunshine of above 9hr/day. The annual sunshine of Pakistan increases from January to June and starts to decrease in August. In September there is a little rise and then there is a continuous drop till December. This variation of the sunshine in Pakistan is generally, because of its latitudinal and altitudinal extent and annual march of the sun.

Keywords: Sunshine, Summer, Winter, Normal Data, vegetation cover, Photosynthesis, Growing season