Chapter-4 climate

1. Choose the correct answer from the four alternatives given below.

(i) The wind blowing in the northern plains in summer is known as:

(ii) Which one of the following causes rainfall during winters in the northwestern part of India?

(iii) Monsoon arrives in India approximately in:

(iv) Which one of the following characterises the cold-weather season in India?

Explanation
(i) Loo is the name of the summertime breeze that blows across the northern plains. A loo is a summer afternoon wind that blows over the western Indo-Gangetic Plain region of North India and Pakistan. It is a strong, hot, and dry wind that originates in the west. May and June are very good months for it. 

(ii) Rainfall is brought on by western disturbances in the northern section of India during the winter. Westerlies are the pattern's primary driver. Western disturbances have a crucial role in the growth of the Rabi crop, which includes the crucial native grain wheat, in the northern subcontinent. 

(iii) The length of the incoming monsoon June through mid-September in India. This indicates that around early June, monsoon season begins in India. Was this response useful? 

(iv) Warm days and chilly nights: The cold season is typically characterised by warm days and chilly nights in Northern India.


2. Answer the following questions briefly.

(i) What are the factors affecting the climate of India?

(ii) Why does India have a monsoon type of climate?

(iii) Which part of India does experience the highest diurnal range of temperature and why?

(iv) Which winds account for rainfall along the Malabar Coast?

(v) Define monsoons. What do you understand by “break” in monsoon?

(vi) Why is the monsoon considered a unifying bond?

Explanation

(i) The following factors influence India's climate: 1. Latitude 2. Altitude 3. Pressure and Winds 

(ii) A specific seasonal pattern defines the monsoon type of climate. The weather significantly varies from season to season. The interior of the country is where these changes are most apparent. While there is variety in the pattern of rainfall, there is not much change in temperature in the coastal regions.

India has four distinct seasons: the cold season, the hot season, the advancing monsoon, and the retreating monsoon, with some regional differences.

The monsoon winds have a significant impact on India's climate. Beginning in early June, the monsoon lasts between 100 and 120 days. 

(iii) This phenomena is being experienced in parts of northwest India. The Thar desert is the cause of this impact. Moreover, there is no ocean in this area to help regulate the temperature. 
(iv) Rainfall along the Malabar Coast is brought on by southwest monsoon winds. 
(v) The movement of the monsoon trough is related to monsoon breaks. Rainfall is distributed spatially depending on whether the trough and its axis are moving northward or southward for various causes. Rainfall in these areas is good when the monsoon trough's axis passes across the plains. While broad rain falls in the mountainous catchment areas of the Himalayan rivers, there are prolonged dry spells in the plains whenever the axis moves closer to the Himalayas. 
(vi) Throughout the Indian subcontinent, the monsoon has a definite unifying effect. A cyclic cycle of seasons is created by the seasonal changes in wind patterns and the accompanying weather. Even the unpredictable rain and uneven distribution are distinctly monsoonal. This phenomena is essential to the Indian landscape, animal and plant life, agricultural calendar, and way of life (including celebrations). India's citizens eagerly await the monsoon's arrival from north to south and from east to west each year. These monsoon winds unite the entire nation by supplying water to start agricultural production. The river valleys that carry this water come together to form one cohesive river valley. 

3. Why does the rainfall decrease from the east to the west in Northern India?

Explanation

The breezes become less moist as they move in that direction. Hence, the decrease in rainfall can be explained.

4. Give reasons as to why.

(i) The Tamil Nadu coast receives winter rainfall.

(ii) The delta region of the eastern coast is frequently struck by cyclones.

(iii) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.

Explanation

(i) It is a result of the winds from the North-East monsoon.

(ii) Pressure shifts occur frequently in the Bay of Bengal. 

(iii) Because they are located in the Aravali Mountains' rain shadow.


5. Describe the regional variations in the climatic conditions of India with the help of suitable examples.

Explanation

The cold weather season lasts from mid-November to February in northern India. The coldest months in the northern section of India are December and January. From south to north, the temperature drops. While it varies between 10°C and 15°C in the northern plains, the average temperature in Chennai, on the eastern coast, is between 24° and 25° Celsius. The nights are cold and the days are warm. In the north, frost is typical, and snowfall occurs on the Himalayas' higher elevations 2. The Deccan plateau had a maximum temperature of roughly 38° Celsius in March. In April, the mercury hovers around 42 degrees Celsius in Gujarat and Madhya Pradesh. In the country's northwest, temperatures of 45 °C are typical for the month of May.

6. Discuss the mechanisms of the monsoon.

Explanation

(a) While the surrounding waters experience relatively high pressure, the landmass of India experiences low pressure due to the differential heating and cooling of the land and water.

(b) The Inter Tropical Convergence Zone's (ITCZ) summertime repositioning over the Ganga Plain. (This is the equatorial trough, which is typically found 5° north of the equator. During the monsoon season, it is sometimes referred to as the monsoon trough.)


(c) The presence of the high pressure area, roughly at 20°S over the Indian Ocean, east of Madagascar. The Indian Monsoon is impacted by this high-pressure area's strength and location.

(d) As a result of the Tibetan Plateau's extreme summer heat, powerful vertical air currents and the development of low pressure systems over the plateau occur at roughly 9 kilometres over sea level.

(e) The tropical easterly jet stream's presence across the Indian peninsula in the summer and the westerly jet stream's travel north of the Himalayas.

7. Give an account of weather conditions and characteristics of the cold season.

Explanation

In northern India, the cold weather season starts around the middle of November and lasts through February. The coldest months in the northern section of India are December and January. As we travel northward from the south, the temperature drops. On the eastern coast, Chennai often experiences temperatures between 24 and 25 degrees Celsius. The temperature fluctuates between 10°C and 15°C in the northern plains at the same time. The nights are chilly and the days are hot here. In the north, frost is typical, and snowfall can be seen on the Himalayas' higher slopes. The northeast trade winds dominate the nation during this time. It is a dry season for the majority of the country since they blow from land to sea. These winds, which blow from the sea to land in this area, cause some rainfall along the coast of Tamil Nadu. A weak high-pressure area forms in the northern section of the country, and mild winds emanate from it. These winds originate in the west and northwest and are influenced by the relief as they pass through the Ganga Valley. The typical weather features include a clear sky, low humidity, low temperatures, and weak, erratic winds. The arrival of cyclonic disturbances from the west and northwest is a defining aspect of the cold weather season over the northern plains. Together with the westerly flow, these low-pressure systems migrate into India from the Mediterranean Sea and western Asia. Across the plains, they bring about much-needed winter rains, and the mountains get snowfall. Although though the total amount of winter precipitation, or "Mahawat," is very minor, it is crucial for the production of "rabi" crops. There is no clearly defined cold season in the peninsular region. Due to the sea's moderating effect, there is virtually any discernible seasonal variation in temperature patterns during the winter.


8. Give the characteristics and effects of the monsoon rainfall in India.

Explanation
Unlike the trade winds, the monsoon fluctuates due to the many atmospheric conditions it encounters as it travels across the warm tropical waters. The monsoon season lasts from early June to mid-September for 100 to 120 days. The typical rainfall abruptly increases around the time of its arrival and then continues steadily for many days. The pre-monsoon rains are separated from this by being referred to as the "burst" of the monsoon. By the first week of June, the monsoon typically makes its way to the southernmost point of the Indian peninsula. The Arabian Sea branch and the Bay of Bengal branch are the next two divisions after that. The Arabian Sea branch arrives in Mumbai roughly 10 days after the10th of June. This is a fairly quick development. The Bay of Bengal branch also moves quickly, and in the first week of June it reaches Assam. The tall mountains cause the monsoon winds to divert over the Ganga Plains to the west. The Arabian Sea branch of the monsoon passes over Saurashtra-Kachchh and the nation's centre by mid-June. Over the western portion of the Ganga Plains, the Arabian Sea and Bay of Bengal monsoon branches combine. Towards the end of June, Delhi often receives monsoon rains from the Bay of Bengal branch (tve date is 29th of June). Western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan all experience the monsoon by the first week of July. Mid-July is when the monsoon arrives.