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Climate
The sum total of weather over a period constitutes the
climate. It is the net result of various factors, the most important of
which are temperature, precipitation, wind, sunshine and clouds. Climate
has a profound effect on the economic development of a region. It has
also a great bearing on the social and cultural activities of the people.
Seasons
There are three well defined seasons in the Punjab. These are:
1. Hot Season (mid-April to the end of June)
2. Rainy Season ( early July to the end of September)
3. Cold Season (early December to the end of February)
The transitional seasons are:
1. Post-monsoon (September to end of November). It is
transitional period between the rainy and cold seasons.
2. Pre-hot season (March to mid-April). It is a
transitional period between the cold and hot seasons.
Hot Season
The temperature begins to rise from February onwards.
Though the real hot seasons starts in mid-April, the rising temperature
breaks the high pressure belt in the north-west of the Indian peninsula.
The atmospheric pressure over this region in February is about 987 milli
bars. The minimum is reached in early June when it is near about 970 milli
bars.
Rainy Season
This is the most welcome season and the agricultural
year starts with its advent. Monsoon winds reach the region normally in
the first weeks of July. The Bay of Bengal branch of the monsoon current
is the main source of rainfall.
Winter Season
The fall in temperature is minimum in January, when
the mean temperature falls to 12oC during day time and to 5oC
during the night. The winter season, cherished by the affluent, becomes
a curse for the poor who cannot afford warm clothing
Post-Monsoon Transitional Season
Monsoon normally retreat by the middle of September.
With this a gradual change in weather takes place and continuous so till
the end of November. Thus October and November are the months with transitional
climates between rainy and winter seasons. The weather remains generally
dry and fair.
Post-Winter Transitional Season
By early March the winter season begins to fade and
by the middle of April, it ultimately emerges as hot season. At times
there may be a shower or two accompanied by hail storms and squalls which
do a lot of damage to crops.
The winds are warm and dry during the last days of March,
it is the time for harvest.
Temperature
The sub-tropical latitudinal and continental location
of Punjab makes the variation of temperature from month to month very
high. Though the minimum air temperature rarely drops below 0o
C, ground frost is a common phenomenon in mid -winter. The rise in temperature
is gradual when the air has high moisture content with the sky remaining
overcast; the rise is however steep when the sky is clear and there is
little moisture content in the air.
The highest day time temperature is recorded during
the months of May and June. It is 40.4o C at Patiala,
40.4o C at Amristar and 41.2o C at Ludhiana. At
Ludhiana the highest maximum temperature on record was 46.1o
C while at Amritsar and Patiala the highest record was 45.5o
C. The daily maximum temperature at Ludhiana remains above 41o
C for 45 days in a year. The lowest maximum temperature is recorded during
the month of January . When the sun's rays are more oblique as compared
to the other months. The cold winds check the rise of day temperature.
The minimum temperature is lowest from December to February.
The lowest minimum temperature recorded at Amristar is 0.2o
C and at Ludhiana 0.5oC. At Amristar the minimum temperature
remain below 5oC for 55 days. The maximum number of days with
the lowest night time temperature are in the month of January. The highest
minimum temperature is recorded in the month of June. When it is even
higher than the day temperature of December and January. At Ludhiana for
55 days in the year the minimum temperature is as high as 27o
C. The maximum number of days with such high night temperature are
in the month of June. The annual range of temperature all over the state
is around 21oC. The mean monthly range of temperature varies
from 9oC in July to about 18oC in November.
Rainfall
The amount of rainfall in the Punjab ranges between 250
mm and 1000 mm. The maximum falling near the Shivalik Hills and the minimum
towards the desert in the west. 70 to 80 percent of the total rainfall
is concentrated during the three months of south-west monsoon winds and
the rest comes during the winter months. There is wide difference in the
amount of rainfall experienced in east and west Punjab. Near the hills
rainfall is over 1000 mm. Gurdaspur, Hoshiarpur, Ropar district
and eastern parts of Patiala receive an annual rainfall of more than 750
mm. The 500 mm rainfall line runs in a north-west to south-east direction
and cuts the Punjab into almost two equal zones. The Fazilka tehsil in
the extreme west receive a rainfall of less than 250 mm.
Monsoon Rainfall
The major part of annual rainfall is experienced during
the monsoon period, when the monsoon current in the Bay of Bengal enters
from the south-east. The normal onset of the monsoon in Punjab is in the
first week of July.
Winter Rainfall
During the winter season, weather in Punjab is normally
cool and dry. This type of weather is associated with the passage of western
disturbances through the region.
The importance of winter rainfall in Punjab is immense
primarily because of its time and effectiveness. In the area adjoining
the Shivalik Hills, winter crops is dependent upon this rainfall. The
sub-Shivalik region receives more than 100 mm of rainfall from December
to March. |
