Please refer to Climate Class 9 Notes and Questions with solutions below. These revision notes and important examination questions have been prepared based on the latest Social Science books for Class 9. You can go through the questions and solutions below which will help you to get better marks in your examinations.
Climate Class 9 Notes and Questions
- General weather conditions over a period of thirty years period is said to be the climate of a place.
- Weather refers to the state of the atmosphere over an area at any point of time.
- Temperature, atmospheric pressure, wind, humidity and precipitation are elements of weather and climate.
- Generalised monthly atmospheric conditions determine the basis on which the year is divided into the seasons — summer, winter or rainy.
- India has a monsoon type of climate.
- Monsoon is basically a seasonal reversal in the wind through the year.
- There is huge difference in temperature from one region to another.
- Form of precipitation, its amount and distribution also differ from one part of India to another.
- Coastal areas observe lesser difference in temperature conditions. It is the interior of India that experiences temperature contrasts.
- Decrease in rainfall is seen from east to west in the Northern Plains. All this influences diversity in professions, food, dress and houses of people.
- The interplay of latitude, altitude, distance from the sea, pressure and wind system, ocean currents and relief features determine climatic conditions of a place.
Factors Affecting India’s Climate
- Latitude, altitude and pressure and winds affect Indian climate.
- The Tropic of Cancer passes through the middle of the country from the Rann of Kuchchh to Mizoram.
- Air temperature generally decreases from equator to poles.
- Temperature and air pressure decreases as on moves from surface of the earth to higher altitudes.
- The Himalayas prevent the cold winds from central Asia from entering the subcontinent.
- The climate and associated weather conditions in India are governed by various atmospheric conditions namely pressure and surface winds, upper air circulation, western cyclonic disturbances and tropical cyclones.
- The sea exerts a moderating influence on climate.People far away from sea experience extreme weather conditions. This is known as ‘continentality’.
- Ocean currents also affect the climate of the coastal areas.
- An apparent force caused by the earth’s rotation is the Coriolis Force.
- The wind direction changes as per the season. They are from north east to south wet in winter whereas completely reverse in summer bringing moisture.
- Jet streams are narrow belts of high-altitude (above 12,000 m) westerly winds in the troposphere.
- The western cyclonic disturbances are weather phenomena of the winter months, brought in by the westerly flow from the Mediterranean region.
The Indian Monsoon
- The climate of India is strongly influenced by monsoon winds.
- The Arab traders who noticed these winds named it as monsoon.
Following facts are important to understand mechanism monsoons –
1. The differential heating and cooling of land and water.
2. The Inter Tropical Convergence Zone (ITCZ) is a broad trough of low pressure in equatorial latitudes where the northeast and the southeast trade winds converge.
3. The presence of the high pressure area, east of Madagascar.
4. The intense heating of Tibetan plateau during summer.
5. The movement of the westerly jet stream to the north of the Himalayas and the presence of of the tropical easterly jet stream over the Indian peninsula during summer.
- Apart from his changes in the pressure conditions over the southern oceans also affect monsoon.
- The periodic change in pressure conditions known as ‘Southern Oscillation’ or SO affects monsoon too.
- El Nino is a warm ocean current that flows past the Peruvian coast in place of the cold Peruvian current, every 2 to 5 years.
The Onset of the Monsoon and Withdrawal
- The monsoon are pulsating winds affected by different atmospheric conditions encountered by it, on its way over the warm tropical seas.
- Monsoon arrives at the southern tip of the Indian peninsula generally by first week of June.
- Sudden increase and continuation of the monsoon for several days is called as ‘burst’.
- The Arabian Sea and the Bay of Bengal branches of the monsoon merge over the north western part of the Ganga plains.
- The withdrawal or the retreat of the monsoon is a more gradual process which begins in the northwestern states of India by early September.
- The retreating monsoon or the transition season sees the change from hot rainy season to dry winter conditions.
- The low pressure conditions over northwestern India get transferred to the Bay of Bengal by early November causing cyclonic depressions originating over the Andaman Sea.
Distribution of Rainfall
- Owing to the nature of monsoons, the annual rainfall is highly variable from year to year.
- Areas of high rainfall are liable to be affected by floods while areas of low rainfall are drought prone.
- Four main seasons can be identified in India — the cold weather season, the hot weather season, the advancing monsoon and the retreating monsoon with some regional variations.
- In the cold weather season the northeast trade winds prevail over India. Days are warm and nights are cold.
- Frost is common in the north and the higher slopes of the Himalayas experience snowfall.
- The summer months experience rising temperature and falling air pressure in the northern parts of the country.
- A striking feature of the hot weather season are strong, gusty, hot, dry winds blowing during the day over the north and northwestern India called loo.
- In the advancing monsoon, i.e. the rainy season, the north-western region of the country receives the maximum rainfall.
- The dust storms in northern India are common.
- The localised thunderstorms, associated with violent winds, torrential downpours, often accompanied by hail. In west Bengal they are known as ‘Kaal Baisakhi’.
- From June onwards the monsoon occupies most of the Indian Peninsula and central part within a month.
- Monsoon has ‘breaks’ in rainfall, thus it has wet and dry spells.
- The alternation of dry and wet spells vary in intensity, frequency and duration causing heavy floods in one part and droughts in the others.
- By the beginning of October the monsoon withdraws from Northern plains.
- The conditions of high temperature and humidity, the weather becomes rather oppressive during the day and is called as October heat.
- Rainfall in India ranges from 400 cm in western coast and northeastern India to 60 cm in Western Rajasthan and adjoining area.
Monsoon as a Unifying Bond
- The dependence of farmers on rain, a change in seasonal cycle, variance in temperature, the needs of humans, plants and animals, festival dates etc., all depend on monsoon in India. In this way monsoon is a unifying bond for Indians.
Question 1: Choose the correct answer from the four alternatives given below.
(i) Which one of the following places receives the highest rainfall in the world?
(ii) The wind blowing in the northern plains in summers is known as:
(a) Kaal Baisakhi
(b) Trade Winds
(d) None of the above
(iii) Which one of the following causes rainfall during winters in north-western part of India?
(a) Cyclonic depression
(b) Western disturbances
(c) Retreating monsoon
(d) Southwest monsoon
(iv) Monsoon arrives in India approximately in:
(a) Early May
(b) Early June
(c) Early July
(d) Early August
(v) 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
Question 2: Answer the following questions briefly.
Question What are the controls affecting the climate of India?
Answer: Latitude, Altitude and Pressure and Winds are the main factors which affect the climate of India.
Question Why does India have a monsoon type of climate?
Answer: India comes in the Inter Tropical Convergence Zone (ITCZ). This fact; in association with various other factors, like the El Nino, Jet Stream and Coriolois Force are the reasons for monsoon type of climate in India.
Question Which part of India does experience the highest diurnal range of temperature and why?
Answer: Northwestern part of India experiences the highest diurnal range of temperature. This happens because of the presence of the Thar Desert and also because this region does not have the moderating influence of the ocean.
Question Which winds account for rainfall along the Malabar coast?
Answer: Monsoon winds
Question What are Jet streams and how do they affect the climate of India?
Answer: Fast flowing and narrow air currents are called jet streams. The streams flow at high altitudes (about 12,000 feet) in the troposphere. The westerly jet streams are responsible for western cyclonic disturbances in the north and north-western parts of India. The subtropical westerly jet stream moves north of the Himalayas with the apparent movement of the sun. The tropical jet stream (an easterly jet stream) blows over the Indian Peninsula; approximately over 14° north during the summer months.
Question Define monsoons. What do you understand by “break” in monsoon?
Answer: The seasonal reversal in wind direction during a year is called monsoon.
Monsoon tends to have ‘breaks’ in rainfall; which means that there are wet and dry spells in between. The monsoon rains take place only for a few days at a timeand then come the rainless intervals.
Question Why is the monsoon considered a unifying bond?
Answer: Although there are wide variations in weather patterns across India, the monsoon brings some unifying influences on India. The Indian landscape, its flora and fauna, etc. are highly influenced by the monsoon. The entire agricultural calendar in India is governed by the monsoon. Most of the festivals in India are
related to agricultural cycle. These festivals may be known by different names in different parts of the country, but their celebration is decided by the monsoon. It is also said that the river valleys which carry the rainwater also unite as a single river valley unit. Due to these reasons, monsoon is often a great unifying factor in India.
Question 3: Why does the rainfall decrease from the east to the west in Northern India?
Answer 3: The Bay of Bengal branch of the monsoon winds moves towards northeast and return westwards covering the northern plains. While they move towards west, their moisture contains tends to reduce with subsequent rains. Hence the rainfall decreases from east to west in northern India.
Question 4: Give reasons as to why.
Question. Seasonal reversal of wind direction takes place over the Indian subcontinent?
Answer: Seasonal reversal of wind direction over the Indian subcontinent takes place due to pressure differential. El Nino has major role to play in the seasonal reversal of wind direction over the Indian subcontinent.
Question. The bulk of rainfall in India is concentrated over a few months.
Answer: The monsoon begins from 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.
Question. The Tamil Nadu coast receives winter rainfall.
Answer: The Tami Nadu coast receives winter rainfall because of movement of lowpressure conditions to the Bay of Bengal.
Question. The delta region of the eastern coast is frequently struck by cyclones.
Answer: The Bay of Bengal is the centre of various pressure changes and hence there is always a chance of development of cyclone. Due to this, the delta region of the eastern coast is frequently struck by cyclones.
Question. Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.
Answer: The parts fall in the rain shadow area of the Aravalli. Hence, they are drought prone.
Question 5: Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Answer 5: Indian Peninsular shows wide variations in climatic conditions across various regions. For example; during winter season, the temperature goes into negative in the Himalayan region. In the northwestern India, temperatures can range between zero degree to 15°C during winter. During the same season, the temperature in Chennai remains a comfortable 25°C. The same variation can be seen in summer as well, while the temperature in Rajasthan can hover around 47°C, it is a comfortable 30°C in Chennai.
Question 6: Discuss the mechanism of monsoons.
Answer 6: The low-pressure condition over the northern plains intensifies by the beginning of June. It attracts the trade winds from the southern hemisphere. These southeast trade winds cross the equator and blow in a south-westerly direction to enter the Indian peninsula as the south-west monsoon. These winds bring abundant moisture to the subcontinent.
Question 7: Give an account of weather conditions and characteristics of the cold season.
Answer 7: The temperature ranges between 10°-15°C in the northern plains. The weather is usually marked by clear sky, low temperatures and low humidity and feeble variable winds. The inflow of the 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.
Question 8: Give the characteristics and effects of the monsoon rainfall in India.
Answer 8: Monsoon tends to have ‘breaks’ in rainfall; which means that there are wet and dry spells in between. The monsoon is famous for its uncertainties. It may cause heavy floods in one part of the country, and may be responsible for droughts in other part. Because of its uncertain behaviour, it sometimes disturbs the farming schedule in India. This affects millions of farmers all over the country.
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