Question

Define the onset and retreat of monsoon according to NCERT 9th standard

Answer 1

CLIMATE 
Climate refers to the sum total of weather conditions and variations over a large area for a long period of time. 
It is the sum total of weather conditions for larger area. 
Eg: for a country: 
WEATHER: 
It refers to state of atmosphere over an area at any point of time. 
It is the total of weather conditions for limited area. 
Eg: for a city 
The elements of weather and climate are temperature, atmospheric pressure, wind, humidity and precipitation. 

INDIAN CLIMATE• 
The climate of India is monsoon type. 
•Monsoon is derived from ‘mausim’which means season and it refers to the seasonal reversal in the wind direction during a year. 
•In Asia, this type of climate is found mainly in south and south-east. 

DIFFERENCES IN INDIAN CLIMATE 
In summer the temperature of Rajasthan is about 50’C but in Jammu & Kashmir it’s 20’c. 
In winter at J&K the temperature is -45’C but in Thiruvanantapuram its 22’C. 
While precipitation is in the form of snowfall in upper parts of Himalyas, it rains over the rest of country. 
Most parts receive rainfall from June to July but some like Tamil Nadu receive it even in the season of October and November. 

CLIMATIC CONTROLS 
The major controls of climate are: 
1.Latitude : Due to curvature the amount of solar energy received varies according to it. 
2.Altitude: As we go higher there is a decrease in temperature of 16’ 
3.Pressure and Wind system: As per latitude and altitude temperature and rainfall also influences the climate. 
4.Distance from sea: The sea exerts moderating influence on climate, regions near sea experiences moderate climate. 
5.Ocean Currents: It leads continentality which means very hot during summers and very cold during winters. 






THE COLD WEATHER SEASON (WINTER) 
1. The cold weather season begins from mid- November in northern India and stays 
till February. 
2. December and January are the coldest months in the northern part of India. 
3. The temperature decreases from south to the north. 
4. Days are warm and nights are cold. 
5. Frost is common in the north and the higher slopes of Himalayas experience 
snowfall. 
6. The northeast trade winds blow from land to sea and hence, for most part of the 
country, it is a dry season. 
7. Some amount of rainfall occurs on the Tamil Nadu coast from these winds as, 
here they blow from sea to land. 
8. The weather is normally marked by clear sky, low temperatures and low humidity 
and feeble variable winds. 
9. A characteristic feature of the cold weather season over the northern plains is a 
the inflow of cyclonic disturbances from the west and the northwest. 
10.They cause the much- needed winter rains over the plains and snowfall in the 
mountains. 
11.Total amount of winter rainfall locally known as ‘mahawat’ is small; they are of . immense importance for the cultivation of ‘rabi’ crops. 
12. The peninsular region does not have well- defined cold season. 

THE HOT WEATHER SEASON (SUMMER) 

1. From March to May, it is hot weather season in India. 
2. The influence of shifting of the heat belt can be seen clearly from temperature 
recordings taken during March- May at different latitudes. 
3. In peninsular India, temperature remain lower due to the moderating influence of the 
oceans. 
4.The summer months experience rising temperature and falling air pressure in the 
northern part of the country. 
5. Towards the end of May, an elongated low pressure area develops in the region 
extending from the Thar Desert in the northwest to Patna and Chotanagpur plateau 
and southeast. 
6. The striking feature of the hot weather season is the ‘loo’. These are strong, gusty, hot, dry winds blowing during the day over the north and northwestern India. 
7. Dust storms are very common during the month of May in northern India. These 
storms bring temporary relief as they lower the temperature and may bring light rain 
and cool breeze. 
8. In West Bengal, these storms are known as ‘Kaal Baisakhi’. 
9. Towards the close of the summer season, pre- monsoon showers are common 
especially, in Kerala and Karnataka. 

Answer 2

In simple words, retreating means withdrawal. So, withdrawal of south-west monsoon winds from skies of north India during months of October and November is known as retreating monsoon. The withdrawal is gradually and takes about three months.