NCERT Solutions for Class 9 Geography Chapter 4 - Climate

Q1. Choose the correct answer from the four alternatives given below.

(i) Which one of the following places receives the highest rainfall in the world?
(a) Silchar 
(b) Mawsynram 
(c) Cherrapunji 
(d) Guwahati
Ans: (b) Mawsynram

Mawsynram, located in the state of Meghalaya, India, is known for receiving the highest rainfall in the world.

(ii) The wind blowing in the northern plains in summers is known as:
(a) Kaal Baisakhi 
(b) Loo 
(c) Trade Winds 
(d) None of the above
Ans: (b) Loo

The Loo is a hot, dry wind blowing across the northern plains of India during the summer months

(iii) Monsoon arrives in India approximately in:
(a) Early May
(b) Early July
(c) Early June
(d) Early August
Ans: (c) Early June

Monsoon generally arrives in India around early June, bringing much-needed rain to various parts of the country.

(iv) Which one of the following characterises the cold-weather season in India?
(a) Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights
Ans: (b) Warm days and cold nights

The cold-weather season is characterized by warm days and cold nights, as daytime temperatures are more comfortable compared to the significantly colder nighttime temperatures.

Q2. Answer the following questions briefly.

(i) What are the controls affecting the climate of India?
Ans: There are six major controls of the climate of any place. They are:

• Latitude
• Altitude
• Pressure & Winds
• Distance from the sea
• Ocean currents
• Relief features

(ii) Why does India have a monsoon type of climate?
Ans: India has a monsoon type of climate because the climate of India is governed by the monsoon winds which are limited between 20° North and 20° South.

(iii) Which part of India does experience the highest diurnal range of temperature and why?
Ans: The Indian desert, located in the north-western part of India experiences the highest diurnal range of temperature because the sand which is present there, quickly becomes hot during the day and cools down rapidly during the night.

(iv) Which winds account for rainfall along the Malabar Coast?
Ans: Malabar Coast gets rains from South-West Monsoon Winds.

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

• Monsoon refers to a wind system that influences large climatic regions and reverses direction seasonally.
• Monsoon ‘break’ refers to the happening of wet and dry spells during the rainy season.
• The monsoon rains take place only for a few days at a time.

(vi) Why is the monsoon considered a unifying bond?
Ans: The monsoon is considered a unifying bond because:

• The monsoon of India is highly influenced by its flora and fauna.
• The water for agricultural activities is provided by these monsoon winds.
• Most of the festivals in India that are related to the agricultural cycle may be known by different names in different parts of the country, but their celebration is decided by the monsoon.
• The river valleys which carry this water also unite as a single river valley unit.

Q3. Why does the rainfall decrease from the east to the west in Northern India?
Ans:

• The low-pressure area in India lies in the northwest, towards which the South West Monsoon winds are attracted.
• After depositing moisture in south India, the Bay of Bengal branch of the South West Monsoons strikes the Khasi-Garo Hills.
• After causing heavy rainfall on the windward slopes, these winds turn westwards because of the presence of the lofty Himalayas. 
• These winds then keep depositing rainfall, they go up the Ganga Valley towards the low-pressure area. 
• The rainfall deposited thus keeps on decreasing as the winds proceed from east to west in Northern India, as this is the last region to be affected by the monsoons.

Q4. Give reasons as to why.

(i) Seasonal reversal of wind direction takes place over the Indian subcontinent.
Ans: The seasonal reversal of wind direction over the Indian subcontinent happens because:

1. Winter Pressure: In winter, a high-pressure area forms north of the Himalayas, causing cold winds to blow towards low-pressure areas over the oceans.

2. Summer Low Pressure: In summer, a low-pressure area develops over interior Asia and northwestern India, reversing the wind direction.

3. Wind Movement: Air moves from the high-pressure zone over the southern Indian Ocean, flowing southeast, crossing the equator, and turning towards the low-pressure areas in India.

4. Monsoon Winds: These winds, known as the Southwest Monsoon winds, carry moisture and bring widespread rainfall to India.

This combination of pressure systems leads to the seasonal change in wind direction.

(ii) The bulk of rainfall in India is concentrated over a few months.
Ans: The monsoon begins in the first week of June and advances quite rapidly to cover almost the whole country by mid-July. Hence, the bulk of rainfall in India is concentrated over the months of a few months; mainly June to August.

(iii) The Tamil Nadu coast receives winter rainfall.
Ans: The Tamil Nadu coast receives winter rainfall because of the movement of low-pressure conditions to the Bay of Bengal.

(iv) The delta region of the eastern coast is frequently struck by cyclones.
Ans: The Bay of Bengal is the centre of various pressure changes and hence there is always a chance of the development of a cyclone. Due to this, the delta region of the eastern coast is frequently struck by cyclones.

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

• Relief/Mountains play an important role in the distribution of rainfall in India. The moisture-laden winds (South West Monsoons) cause heavy rain on the windward slopes of the Western Ghats and Khasi-Garo hills. 
• When winds cross over mountains, they lose most of their moisture on the windward side (the side facing the wind), resulting in less rainfall on the leeward side (the side sheltered from the wind). This dry area on the leeward side, which gets very little rain, is often drought-prone.
• Rajasthan is an example of such a region; it lies in the rain shadow of the Aravalli Hills, meaning it receives significantly less rainfall compared to areas on the windward side of the hills.

Q5. Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Ans:

• There is regional variation in the climatic conditions of India. Temperature and Precipitation vary from place to place and season to season.
• During the summer season, the temperature rises up to 50°C in parts of Rajasthan, whereas it may be around 20°C in Pahalgam in Kashmir.
• During the winter season at night, the temperature in Drass in Kashmir may be minus 45°C, whereas in Thiruvananthapuram in Kerala may have a temperature of 20°C.
• In the Andaman Islands, the difference between the temperatures of day and night may be hardly 7° - 8°C.
• Coastal areas experience less contrast in the temperature, whereas seasonal contrasts are more in the interior of the country.
• There is a decrease in rainfall generally from east to west in the northern plains.
• Most parts of India receive rainfall from June - September, whereas some parts like the Tamil Nadu coast get a large portion of its rain during October and November.

Q6. Give an account of weather conditions and characteristics of the cold season.
Ans: The following are the features of the cold season:

• The winter season begins from mid-November and continues till February; in northern India.
• December and January are the coldest months in the northern part of India.
• The temperature ranges between 10°-15°C in the northern plains, while it ranges between 24°-25°C in Chennai.
• Days are warm and nights are cold.
• Frost is common in the north and the higher slopes of the Himalayas experience snowfall.
• The northeast trade winds prevail over the country in this season. As these winds blow from land to sea, most parts of the country experience a dry season.
• The weather is usually marked by a clear sky, low temperatures, low humidity and weak variable winds.
• The inflow of cyclonic disturbances from the west and the northwest is a characteristic feature of the cold weather over the northern plains.
• These low-pressure systems originate over the Mediterranean Sea and Western Asia and move into India. They cause winter rains over the plains and snowfall in the mountains.
• The winter rainfall is in small amounts but is very important for the rabi crop. This rainfall is locally known as mahawat.
• The peninsular region does not have a well-defined cold season due to the moderating influence of the sea.

Q7. Give the characteristics and effects of the monsoon rainfall in India.
Ans: Characteristics of the monsoon rainfall in India:

• The duration of the monsoon varies from 100 to 120 days from early June to mid-September.
• The normal rainfall suddenly increases, around the time of its arrival and continues regularly for several days. This is called the ‘burst' of the monsoon.
• They are distinguished from the pre-monsoon showers because of their increase in rainfall amount and regularity.
• The monsoon arrives at the southern tip of the Indian Peninsular generally by the first week of June.
• The rainfall is unevenly distributed across the country.

Effects of the monsoon rainfall in India:

• Agriculture in India largely depends on Indian monsoons for water. Late, Low or excessive rains have a negative impact on crops.
• Due to the uneven distribution of rainfall across the country, there are few places that are drought-prone and few are flood-affected.
• The monsoon provides India with a diverse climatic pattern. Hence, despite the presence of great regional variations, it has a unifying influence on the country and its people.

Map Skills

Q. On an outline map of India, show the following.
(i) Areas receiving rainfall over 400 cm.
(ii) Areas receiving less than 20 cm of rainfall.
(iii) The direction of the southwest monsoon over India.
Ans:

(i) The Western Coast and North Eastern India receive rainfall over 400 cm. Mawsynram and Cherrapunji in Meghalaya are known for receiving maximum rainfall in the world. The Andaman Islands and Lakshadweep Islands are also known to receive annual rainfall above 400 cm.
(ii) The parts of Northern Kashmir, Western Rajasthan, Deccan Plateau and Punjab are known to be the areas that receive scanty rainfall that is less than 20 cm. In the Northern part of India, rainfall decreases toward the west, while in the peninsular region except for Tamil Nadu, the rainfall decreases eastwards.
(iii) In early June, a low-pressure area over northern India attracts southeast trade winds from the southern hemisphere. These winds blow southwesterly into India, bringing moisture and abundant rainfall. Moving at about 30 km per hour, the southwest monsoon signals the start of the rainy season, transforming the weather across the country.