Abstract:
The rate of cloud coverage in the sky is influenced by different climatic factors.
That’s why, Cloud coverage and other climatic parameters related to it such as
temperature, rainfall and relative humidity of Bangladesh is the main objective of this
study.
Data (1953 – 2011) of thirty five meteorological stations of Bangladesh have been
collected to achieve the objectives. The source of these climatic data is the Bangladesh
Meteorological Department (BMD). At first the data were processed by using tools
Microsoft Office Access 2003. All the climatic data of different locations are analyzed
in the basis of monthly, yearly and seasonally.
It is identified from analysis that in Bangladesh large amount of cloud coverage
occurs from the month of June to September and in July it is maximum. In July, about
seven eighth portions of the sky are covered by cloud. Small amount of cloud
coverage occurs from the month of November to May and minimum in the months of
December and January. In the month of January and December, only one eighth
portions of the sky are covered by the cloud. Clouds begin to form from the month of
February and in July the cloud formation is in large extent. Again cloud formation
starts to diminish from the month of September and in December and January the
formation is in little extent. In Monsoon season cloud formation is high but it is low in
Dry season in most of the districts of Bangladesh. Annual variation trend at different
location represents that maximum cloud coverage occurs in Sylhet and minimum in
Dinajpur. In Bangladesh temperature is maximum in April or May and is minimum in
January. The average monthly temperature of the country varies from 9˚c to 37˚c.
Maximum average temperature occurs in monsoon seasons (June to October) and
minimum average temperature occurs in dry season (November to February). The
average annual humidity in Bangladesh is 79.52%. In most of the location heavy
amount of humidity occurs from the month of June to October and in July it is
maximum but in March it is minimum. The range of relative humidity varies from
58.56% to 89.9%. From analysis, it is found that the average annual total rainfall of
the country is about 2394.28 mm. Heavy rate of rainfall occurs in the months of June,
July and August at the time of full monsoon and in July the rate is maximum.
Minimum rate of rainfall occurs in the months December and January. Average
annual maximum rainfall occurs in Teknaf (4065.241 mm) and Sylhet (4016.286 mm)
and minimum rainfall occurs in Rajshahi (1484.92 mm). The correlation coefficient
(r) between cloud cover with temperature, humidity and rainfall is large and positive.
It means cloud cover rate is increased with the increasing value of temperature and
humidity. It also means rainfall rate increases with the increasing of cloud cover in the
sky.
