Page 168 - SST Class 06

On the contrary, interior locations are The four main seasons are— (i) Cold Season,
deprived of the moderating influence of the
sea and experience extreme or continental
climate. For example, the annual range of
temperature at Kochi does not exceed 3°C
whereas it is as high at 20°C at Delhi.
Similarly, the amount of annual rainfall at
Kolkata is 119 cm which falls to a low of 24
cm at Bikaner.
5. Pressure and Winds : India has unique
wind and pressure conditions. During
winter, the northern area near the
Himalayas has high pressure. Therefore,
winds from this region blow to the south
where the pressure is lower. In summer, the
northern part has lower pressure. Therefore,
there is a reversal of wind direction. The
winds from the south blow towards the
north. These winds greatly affect the climate
of India.
EQUABLE AND EXTREME CLIMATE
Oceans have a moderating influence on the
climate of coastal areas. Since ocean’s water
does not heat up or cool as quickly as the interior
of the landmasses, the difference between day
and night temperatures of these places is small.
This is known as equable climate. In the interior
region like Ganga plains there is large difference
between the temperatures of the day and that of
night and also of summer season and winter
season. It is called extreme or continental type of
climate. The difference between the maximum
temperature and minimum temperature of the
day is called diurnal range of temperature.
SEASONS
The climate of India has distinct seasonal pat-
terns. The weather conditions change greatly
from one season to another. The changes in
temperature are extreme in the interior regions.
The coastal regions do not experience extreme
temperatures.
Social Science-6 168
(ii) Hot Season, (iii) Advance Monsoon Season
and (iv) Retreating Monsoon Season or Post
Monsoon Season.
1. The Cold Season (December to Feb-
ruary) : During this season, high pressure
prevails over northern plains. The winds
blow form land to sea. The temperature in
the interior parts of northern India decreases
and the mean temperature is of 15°C. It,
however, goes on increasing towards south.
In Kozhikode (Calicut) and Chennai, tem-
perature may be around 20°C to 25°C. In
the northern plains the winters of 2005.
Northern India shivered in unprecedented
low temperature. Freezing temperature were
recorded in some cities. The temperature in
Adampur (Punjab) was 0.4°C, Delhi 0.2°C,
Agra –1°C and Churu (Rajasthan) -29°C. In
South India, especially in coastal areas, due
to influence of the seas, there is not much
difference in day and night temperatures.
Western Disturbances : Western distur-
bances are the low-pressure systems origi-
nating from the Mediterranean Sea. Under
the influence of upper air currents and trade
winds, these storms which come from ocean
to land pass through West Asia and enter
Pakistan. They then strike the Himalaya
causing snowfall in the region. They
descend towards the plain and considerably
lower the temperature and cause small
amounts of rainfall in Haryana, Delhi, parts
of Uttar Pradesh and Bihar.
The north-east monsoon winds blow over
the Bay of Bengal and reach the
Coromandel Coast. It is how Chennai gets
rainfall in winter.
2. Hot Season (March to May): In the
northern belt, the upper air currents begin
shifting northward. The temperature starts