NCERT Solutions for Class 9 Social Science Geography Chapter 4 Climate

Ans : (i)(c) North-Eastern  monsoon


(ii) (d) Three-fourth
(iii) (d) Extreme  climatic  conditions  are  found  here.
(iv) (a) High  pressure  develops  over  North-western  India  due  to  low temperatures.
(v) (c) On  Coromandel  coast 

Ans : (i) The three important factors which influence the mechanism of Indian weather are:
Distribution of air pressure and winds on the surface of the earth.
Upper air circulation caused by factors controlling global weather and the inflow of different air masses and jet streams.
Inflow of western cyclones generally known as disturbances during the winter season and tropical depressions during the south-west monsoon period into India, creating weather conditions favourable to rainfall.


(ii) The Inter Tropical Convergence Zone (ITCZ) is a low pressure zone located at the equatomhere trade winds converge, and so, it is a zone where air tends to ascend.


(iii) The sudden onset of the moisture-laden winds associated with violent thunder and lightning, is often termed as the "break" or "burst" of the monsoons. Mawsynram in Meghalaya is the place of India which gets the highest rainfall.


(iv) A climatic region has a homogeneous climatic condition which is the result of a combination of factors. The bases of Koeppen's classification are:
Temperature
Precipitation


(v) Western cyclonic disturbances cause rainfall in north-western India during winter. They originate over the Mediterranean Sea. 

Ans : (i) Due to the influence of monsoon, India as a whole has broad climatic unity. However, the climate of India has many regional variations expressed in the pattern of winds, temperature and rainfall, rhythm of seasons and the degree of wetness or dryness. There are various examples of this:
Temperature: In the summer the mercury occasionally touches 550C in the western Rajasthan, it drops down to as low as minus 450C in winter around Leh. Churu in Rajasthan may record a temperature of 500C or more on a June day while the temperature in Tawang (Arunachal Pradesh) is 190C on the same day.
Rainfall: Cherrapunji and Mawsynram in the Khasi Hills of Meghalaya receive rainfall
over 1,080 cm in a year while Jaisalmer in Rajasthan rarely gets more than 9 cm of rainfall during the same period.
Monsoon: The Ganga delta and the coastal plains of Orissa are hit by strong rain-bearing storms almost every third or fifth day in July and August while the Coromandel coast, a thousand km to the south, goes generally dry during these months.


(ii) The meteorological department recognise the following four seasons :
(a) the cold weather season
(b) the hot weather season
(c) the southwest monsoon season
(d) the retreating monsoon season.
The cold weather season: The cold weather season sets in by mid-November in northern India.
December and January are the coldest months in the northern plain. The mean daily temperature remains below 210C over most parts of northern India. The night temperature may be quite low. The Peninsular region of India, however, does not have any well-defined cold weather season. There is hardly any seasonal change in the distribution pattern of the temperature in coastal areas because of moderating influence of the sea and the proximity to equator During the winters, the weather in India is pleasant. The pleasant weather conditions, however, at intervals, get disturbed by shallow cyclonic depressions originating over the east Mediterranean Sea and travelling easüards.
Winter monsoons do not cause rainfall as they move from land to the sea. It is because they have little humidity and due to anti cyclonic circulation on land. So, most parts of India do not have rainfall in the winter season. However, there are some exceptions, Rainfall occurs in northwestern India due to western disturbances. Central parts of India and northern parts of southern peninsula also get winter rainfall occasionally.