01 November, 2017

Class IX: Chapter 4 (Climate) Question & Answers

Q1. Name the controls affecting the climate of any place.
Ans: There are six major controls of the climate of any place. They are:
(a) Latitude                                 (b) Altitude                                     (c) Pressure and Wind System
(d) Distance from the Sea           (e) Ocean Currents                         (f) Relief Features.

Q2. What are the elements of weather and climate?
Ans: There are the five major elements of weather and climate, i.e. Temperature, Atmospheric Pressure, Wind, Humidity and Precipitation

Q3. What are Jet Streams?
Ans: Fast flowing air currents in a narrow zone in the upper atmosphere are known jet streams.

Q4. Define monsoons. What do you understand by "break" in monsoon?
Ans: The seasonal reversal in wind direction during a year is called monsoon. The word "Monsoon" has been derived from an Arabic word called "Mausim" which means "Season".
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 time and then come the rainless intervals.

Q5. Why the monsoon is considered a unifying bond?
Ans: Following are few of the reasons why the monsoon is considered as a unifying bond in India:
(a) The Indian landscape, its flora and fauna, etc. are highly influenced by the monsoon.
(b) The entire agricultural calendar in India is governed by the monsoon.
(c) 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.
(d) It is also said that the river valleys which carry the rainwater also unite as a single river valley unit.

Q6. Discuss the mechanism of monsoons.
Ans: Following are the factors responsible for the mechanism of monsoon:
(a) The Sun causes differential heating and cooling of land and water. This creates low pressure on the landmass of India and high pressure over the ocean surface.
(b) The Inter Tropical Convergence Zone (ITCZ) is normally positioned about 5°N of the equator. It shifts over the Ganga plains during summer. It is also known as the monsoon trough during the monsoon season.
(c) The high pressure area, east of Madagascar is approximately 20°S over the Indian Ocean. This area affects the Indian Monsoon.
(d) The Tibetan plateau gets intensely heated during summer. This results in strong vertical air currents and formation of low pressure over the plateau. This low pressure zone is about 9 km above the sea level.
(e) The westerly jet stream move to the north of the Himalayas, and the tropical easterly jet stream moves over the Indian Peninsula during summer.
(f) The periodic change in pressure conditions between Pacific Ocean and the Indian Ocean that is known as the Southern Oscillation or SO also affects the monsoon.
(g) The difference in pressure over Tahiti (18°S/149°W) in the Pacific Ocean and Darwin (12°30'S/131°E) lies in northern Australia predicts the intensity of the monsoons. If the pressure differences are negative, it means a below average and late monsoon.

Q7. Give an account of weather conditions and characteristics of the cold season.
Ans: Following are the features of the cold season:
(a) The winter season begins from mid-November and till February; in northern India. December and January are the coldest months.
(b) The temperature goes low in the northern plains, while moderate in Chennai.
(c) As the northeast trade winds blow from land to sea, most parts of the country experience a dry season.
(d) The weather is usually marked by clear sky, low temperatures and low humidity and weak variable winds.
(e) The inflow of the cyclonic disturbances from the west and the northwest is a characteristic feature of the cold weather over the northern plains.
(f) These low-pressure over the Mediterranean Sea and Western Asia move into India that causes winter rains over the plains and snowfall in the mountains.
(g) The winter rainfall is in small amount but is very important for the rabi crop. This rainfall is locally known as mahawat.
(h) The peninsular region does not get a well-defined winter because of the moderating influence of the sea.

Q8. Write the characteristics of the retreating monsoon or the transition season.
Ans: Following are the characteristics of the retreating monsoon or the transition season:
(a) During October-November, the sun apparently moves towards the south. Thus, the monsoon trough over the northern plains becomes weaker and the south-west monsoon winds start withdrawing. The monsoon withdraws from the northern plains by the beginning of October.
(b) The retreat of the monsoon is marked by clear skies and rise in temperature. Day temperatures are high, nights are cool and pleasant.
(c) High temperature and humidity, makes the weather quite uncomfortable during the day. This is commonly known as "October Heat".
(d) The temperature begins to fall rapidly in northern India by the second half of October.
(e) The low-pressure conditions over northwestern India move to the Bay of Bengal by early November.
(f) This shift leads to cyclonic depressions over the Andaman Sea. These cyclones usually cross the eastern coasts of India and cause heavy and widespread rain. These cyclones may also arrive at the Coasts of Orissa, West Bengal and Bangladesh.
(g) These cyclones contribute to the bulk of the rainfall of the Coromandel Coast.

Q9. Describe the onset and withdrawal of the monsoons in India.
Ans: Onset:
(a) Generally, the monsoon arrives at the southern tip of the Indian peninsular by the first week of June. Subsequently, it divides into two branches, viz. the Arabian Sea branch and the Bay of Bengal branch.
(b) The Arabian Sea branch reaches Mumbai about ten days later, i.e. around 10th of June. The Bay of Bengal rapidly advances and reaches Assam in the first week of June.
(c) The monsoon winds are then deflected by high mountains and move towards west over the Ganga plains. The Arabian Sea branch of the monsoon arrives over Surashtra-Kuchchh and central part of the country by mid-June.
(d) The Arabian Sea and the Bay of Bengal branches of the monsoon merge over the northwestern part of the Ganga plains.
(e) Delhi usually receives monsoon showers from the Bay of Bengal branch by the end of June.
(f) Western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan experience monsoon by the first week of July. The monsoon reaches Himachal Pradesh and the rest of the country by mid-July.

Withdrawal: Withdrawal or the retreat of the monsoon is a more gradual process.
(a) The monsoon begins to withdraw from the northwestern states of India by early September.
(b) The monsoon withdraws completely from the northern part of the Indian peninsular by mid-October.
(c) The monsoon withdraws from the rest of the country by early December.
(d) The islands receive the very first monsoon showers from the first week of April to the first week of May; progressively from south to north. The withdrawal of monsoon in the islands takes place from the first week of December to the first week of January.

Q10. On an outline map of India, show the following:
(a) Areas receiving rainfall over 400 cms.
(b) Areas receiving less than 20 cms of rainfall.
(c) The direction of the south-west monsoon over India.
(d) The Wettest place of the World.
(e) City in the eastern coast having an average temperature between 24-25 degree Celsius in the winter season.





Dhananjay13 November, 2017Superb

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