Class 9 Geography Chapter 1 Question Answers - Contemporary India - I

Q.1. What are jetstreams? How do they affect the climate? (Important)

Ans. Jet streams are fast, narrow air currents in the upper atmosphere that form part of the upper-air circulation.
Over India, a branch of the westerly jet stream blows south of the Himalayas during winter. It brings western cyclonic disturbances from the Mediterranean region, causing winter rain in the northern plains and snowfall in the Himalayas.
In summer, this westerly jet moves north of the Himalayas and a tropical easterly jet stream appears over peninsular India. This shift is linked to the onset and behaviour of the southwest monsoon.

Q.2. What is the loo? How does it affect the weather of a place? (Important)

Ans. The loo is a strong, hot and dry gusty wind that blows over north and north-western India during the hot season, mainly from April to June. It usually occurs in the afternoons and sometimes continues into the evening.
The loo raises daytime temperatures sharply and causes severe dehydration and sunstroke in people exposed to it. It can damage crops and vegetation. Occasionally, dust storms associated with the loo bring temporary relief by lowering temperatures and may be followed by a light shower and cooler breeze.

Q.3. Write a short note on the retreating monsoons. (Important)

Ans. The months of October-November mark the transition from the hot, rainy season to the cool, dry winter. This period is called the retreating monsoon or transition season because the southwest monsoon weakens and withdraws from India. The retreat is associated with clearer skies and a rise in daytime temperature while nights become pleasantly cool. High humidity together with rising temperatures in October often makes the weather oppressive; this is referred to as the October heat.
With the shift of the low-pressure centre towards the Bay of Bengal in early November, cyclonic depressions that form over the Andaman Sea move towards the eastern coast. The Coromandel Coast receives much of its rainfall from these retreating monsoon systems. Such tropical cyclones may cause torrential rain and occasional heavy damage in the densely populated delta regions of Tamil Nadu and Andhra Pradesh.

Q.4. Describe with examples how altitude affects the climate of a place.

Ans. Altitude affects climate because temperature decreases as we go higher from the surface of the earth.
Hill stations in the mountains are cooler than places in the plains since the atmosphere becomes thinner at greater heights. For example, areas in the Himalayas experience very low temperatures and snowfall in winter.
The Himalayas, due to their great height, also stop the extremely cold winds from Central Asia from entering India, giving the northern plains milder winters than regions on similar latitudes.

 Q.5. Describe with examples how distance from the sea influences the climate of a place?

Ans. The sea moderates the climate of nearby places. Coastal cities such as Mumbai, Chennai, Thiruvananthapuram and Kolkata have a maritime climate with a small difference between summer and winter temperatures. As distance from the sea increases, its moderating influence falls and a place displays continentality. Continental interiors experience larger seasonal temperature extremes - very hot summers and very cold winters. For example, Delhi, being well inland, shows a more extreme climate than coastal cities.

 Q.6. What form of precipitation does the upper part of the Himalayas receive and why?

Ans. The upper Himalayas, with altitudes around 6 000 metres, have very low temperatures because temperature decreases with height. As a result, precipitation in these high regions falls mainly as snow. For example, Drass in Jammu and Kashmir can record temperatures as low as -45°C on a winter night, so snowfall is the normal form of precipitation there. Srinagar, Shimla and Manali also receive snowfall during winter when western disturbances bring moisture to the cold high elevations.

Q.7. Write a short note on the trade winds. What are the effects of trade winds on the climate of India?

Ans. The trade winds are planetary winds that blow from the Sub-Tropical High Pressure Belts toward the Equatorial Low Pressure Belt (the doldrums). Due to the Coriolis deflection, they blow as North-East Trade Winds in the Northern Hemisphere and as South-East Trade Winds in the Southern Hemisphere. Trade winds are among the most regular and persistent winds and generally blow steadily in one direction.
India lies in the region of North-Easterly Trade Winds, which, when blowing over land, are usually dry and bring little rainfall. Had trade winds been the only influence, much of India would be arid. However, in late spring and early summer a strong low-pressure area develops over the northern plains and draws in moist south-easterly winds from the Southern Hemisphere. These South-East Trade Winds cross the equator and, after being deflected, become the moisture-laden south-west monsoon that brings the bulk of India's rainfall.

Q.8. Discuss why Mawsynram receives the highest rainfall in the world? (Important)

Ans. Mawsynram in Meghalaya lies on the southern slopes of the Khasi Hills. The Bay of Bengal branch of the southwest monsoon carries very moist air which, on reaching the Garo, Khasi and Jaintia hills, is forced to rise sharply. Because Mawsynram is situated nearly perpendicular to the incoming moisture-laden winds and at the mouth of a deep valley, orographic uplift produces exceptionally heavy rainfall. Mawsynram receives about 1 141 cm of rain per year and has rain for nearly nine months of the year, making it one of the wettest places on earth.

Q.9. What is the Coriolis force? Describe briefly its effect on the climate of the world.

Ans. The Coriolis force is an apparent force produced by the rotation of the earth. It causes moving air to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This behaviour is also known as Ferrel’s Law. Due to this deflection, winds blowing toward the equator become north-easterly trade winds in the Northern Hemisphere and south-easterly trade winds in the Southern Hemisphere. This change in direction helps shape the pattern of planetary winds, which in turn controls temperature and rainfall distribution over the world.

Q.10. Give reasons why the bulk of the rainfall is concentrated over a few months in India. (Important)

Ans. The major part of India's annual rainfall is delivered by the south-west monsoon. The concentration of rainfall in a few months is explained as follows:
(a) By early June a strong low-pressure zone forms over northern India, attracting the moisture-laden south-west monsoon winds which originate over the warm southern oceans.
(b) The monsoon advances rapidly northwards after striking the southern peninsula in early June and by July covers most of the country. The main monsoon season lasts about 100-120 days (early June to mid-September), and the bulk of annual rainfall falls within this period.
(c) Both the Arabian Sea and Bay of Bengal branches of the monsoon bring very heavy rains, especially over the western coast and north-eastern states. Even generally dry areas such as parts of Rajasthan and Gujarat receive some rainfall during the monsoon.

Q.11. Study the climate data of the given place and answer the following questions : (CBSE 2010)

 (a) Find out the annual of temperature of the given place.
 (b) Name the rainiest month.
 (c) Which month receives least rainfall and how much ?

Ans. (a) Annual range of temperature = 27.1 - 18.9 = 8.2 °C
(b) September
(c) January receives the least rainfall = 7 mm.

Q.12. Read the given table and answer the following questions. (CBSE 2010)
 (a) Name two rainiest stations
 (b) Name the station farthest from equator
 (c) Station which has highest range of temperature

Ans. (a) Two rainiest stations are Shillong (225.3 cm) and Mumbai (183.4 cm).
(b) Leh (34°N) is the farthest from the equator.
(c) Leh has the highest annual range of temperature (25.7°C).

Q.13. Study the climate data below and answer the questions. (CBSE 2010)

 (a) Name the rainiest month of the year. What is the reading?
 (b) What is meant by annual range of temperature?
 (c) Which two months have the least rainfall?

Ans. (a) The rainiest month of the year is July (19.1 cm).
(b) Annual range of temperature is the difference between the maximum and minimum mean monthly temperatures in a year, i.e., Maximum temperature - Minimum temperature.
(c) November (1.5 cm) and December (1.5 cm) have the least rainfall.

Q.14. Study the climatic conditions of the two places and answer the following : (CBSE 2010)
 (a) Name the place which receives the most rainfall in winter season and give reason for it.
 (b) Name the place which receives maximum rainfall and how much?
 (c) Name the place which has the lower range of temperature and how much.

Ans. (a) Chennai receives the most rainfall in the winter season among the two places, mainly due to the retreating monsoon and associated cyclonic depressions that move along the east coast.
(b) Shillong receives the maximum annual rainfall. Total rainfall at Shillong (approx.) = 2 + 4 + 6 + 15 + 30 + 45 + 36 + 34 + 30 + 19 + 5 + 1 = 227 cm (approximately).
(c) Range of temperature at Shillong = 20 - 10 = 10°C. Range of temperature at Chennai = 33 - 24 = 9°C. Hence, Chennai has the lower range of temperature (9°C).

Q.15. Study the climate data of the given place and answer the following questions
 (CBSE 2010)

 (a) Find out the annual range of temperature of the given place.
 (b) Name the rainiest month.
 (c) Which month receives the least rainfall and how much ?

Ans. (a) Annual range of temperature = 28.0 - 18.9 = 9.1°C.
(b) September is the rainiest month.
(c) January receives the least rainfall (7 mm).

Q.16. What is the difference between weather and climate ? What kind of a climate does India have and why? (CBSE 2010)

Ans. Weather is the state of the atmosphere over an area at a particular time (for example, a day's temperature, wind and precipitation). Climate is the average pattern of weather and its variations over a long period for a large area. India has a monsoon type of climate. Seasonal reversal of winds and the large seasonal rainfall brought by the south-west monsoon strongly influence India's climate.

Q. 17.

Study the climatic condition of Thiruvananthapuram and answer the following questions :
 (CBSE 2010)
 (a) Which two months receive the lowest rainfall?
 (b) What is the range of temperature in the month of June?
 (c) Which month receives the highest rainfall?
 Ans. (a) January and February receive the lowest rainfall.

(b) Range of temperature in June = 31 - 24 = 7°C.

(c) June receives the highest rainfall.

Q.18. What is ITCZ? What is its significance? (CBSE 2010)
 Ans. ITCZ stands for Inter-Tropical Convergence Zone. It is an equatorial trough normally located a little north of the equator (about 5°N) and is called the monsoon trough during the monsoon season. The ITCZ is significant because it is a zone of converging surface winds and rising air, leading to cloud formation and heavy rainfall over the tropics; its position influences the onset and strength of monsoon rains.

Q.19. Study the data given below carefully and answer the following questions. [2011 (T-2)]

 (19.1) Name the station which is farthest from the Equator.
 (19.2) Name the driest and wettest station among the three stations.

Ans. (19.1) Delhi (29° N) is the station farthest from the equator among the three.
(19.2) Nagpur (1 242 mm) is the wettest station. Jodhpur is the driest of the three; it also shows a large annual range of temperature (33.9 - 14.9 = 19°C).

Q.20. Study the following climatic data and answer the questions that follow : [2011 (T-2)]

(20.1) Name the rainiest month of the year. How much is the rainfall in this month?
(20.2) What is the annual range of temperature here?
(20.3) Name the hottest month and write the temperature.

Ans. (20.1) August is the rainiest month of the year with 33.4 cm of rainfall.
(20.2) Annual range of temperature = 30.4 - 19.6 = 10.8°C.
(20.3) May is the hottest month (30.4°C).

Q.21. Why do western Ghats receive more rainfall than the Eastern Ghats. Explain briefly. [2011 (T-2)]

Ans. The Western Ghats are higher (900-1 600 metres) and form a continuous, steep barrier, while the Eastern Ghats are lower (around 600 metres) and are more broken. When the moisture-laden Arabian Sea branch of the southwest monsoon reaches the western coast, it is forced to rise by the high Western Ghats. This orographic uplift cools the air and causes heavy rainfall on the windward (western) side. The Eastern Ghats do not present a similar continuous barrier to the monsoon winds, so they receive much less rainfall.

 Q.22. What are western disturbances? How do they effect the climate of India? [2011 (T-2)]

Ans. Western disturbances are low-pressure systems that originate over the Mediterranean Sea and western Asia and move eastwards with the westerly flow. They affect the weather of north and north-west India during the winter months. Western disturbances bring light to moderate rainfall over the plains and snowfall in the mountains. Though the total winter rainfall is limited, it is essential for rabi crops and for replenishing soil moisture in the winter season.

Q.23. Explain how monsoon acts as a unifying bond in the country. [2011 (T-2)]
 OR
 Why are the monsoons considered as a unifying bond? Explain.
 OR
 How do monsoon acts as a unifying bond for India? Explain.

Ans. The monsoon unites the Indian subcontinent through its seasonal rhythm and the large-scale effects it produces. The reversal of winds and the arrival of the monsoon determine cropping seasons, agricultural cycles, river flows and water availability. Festivals, livelihoods and local economies are closely linked to the monsoon's timing and strength. People across the country watch and depend on the monsoon each year, and the river valleys fed by monsoon rains connect regions into single agricultural and economic units. In these ways the monsoon acts as a strong unifying bond.

Q.24. Define monsoon. Differentiate between 'Burst of the Monsoon' and 'Break of the Monsoon. [2011 (T-2)]

Ans. The word monsoon comes from the Arabic 'mausim' meaning season. In meteorological terms, monsoon refers to a seasonal change in wind direction accompanied by a marked seasonal change in precipitation; in India it refers particularly to the south-west monsoon that normally lasts about 100-120 days from early June to mid-September.
Difference:
(a) Burst of the Monsoon: At its arrival, normal rainfall rises suddenly and persists for several days. This steady onset is called the burst of the monsoon and marks the effective beginning of the rainy season.
(b) Break of the Monsoon: The monsoon does not bring continuous rain every day; it shows spells of heavy rain interspersed with rainless periods. These rainless intervals are called breaks of the monsoon and are related to shifts in the monsoon trough and circulation patterns.