QUESTION & ANSWERS OF GEOGRAPHY CLASS 9 CH -4 CLIMATE

Geography

Class 9

Chapter-4

Climate

1. Differentiate between Climate and Weather.

2. What are the elements of weather and climate?

Ans.- The elements of weather and climate are the same, i.e. temperature, atmospheric pressure, wind, humidity and precipitation.

3. What type of climate India has and why it is so?

Ans.- The climate of India is described as the ‘monsoon’ type because it is strongly influenced by monsoon wind.

• The monsoon wind is characterised by a distinct seasonal pattern.
• It causes the weather conditions to change from one season to the other.
• These changes are particularly noticeable in the interior parts of India.

4. What does the term monsoon mean?

Ans.- The word monsoon is derived from the Arabic word ‘mausim’ which literally means season.

‘Monsoon’ refers to the seasonal reversal in the wind direction during a year.

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

Or

Despite an overall unity in the general pattern, there are perceptible regional variations in climatic conditions within the country. Explain the statement with the help of examples.

Ans.- Despite an overall unity in the general pattern, there are perceptible regional variations in climatic conditions within the country. For example-

• In summer, the mercury occasionally touches 50°C in some parts of the Rajasthan desert, whereas it may be around 20°C in Pahalgam in Jammu and Kashmir.
• On a winter night, temperature at Drass in Jammu and Kashmir may be as low as minus 45°C. Thiruvananthapuram, on the other hand, may have a temperature of 22°C.
• Precipitation is mostly in the form of snowfall in the upper parts of Himalayas, whereas it rains over the rest of the country.
• The annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and western Rajasthan.
• Most parts of the country receive rainfall from June to September. But some parts like the Tamil Nadu coast get a large portion of its rain during October and November.

6. Why the houses in Rajasthan have thick walls and flat roofs?

Ans.- The houses in Rajasthan have thick walls to prevent the heat from entering into the houses while the flat roofs help to retain the little water that has been collected during rainfall.

7. Why is it that the houses in the Tarai region and in Goa and Mangalore have sloping roofs?  

Ans.- The houses in Tarai region, Goa and Mangalore have sloping roofs because these regions receive heavy rainfall. Therefore, when the houses have sloping roofs, it helps them to get rid of the collected rainwater which flows down from the roof to the ground.

8. Why houses in Assam are built on stilts?

Ans.- Houses in Assam are built on stilts because the state receives plentiful rainfall due to which there are chances of floods. So in order to avoid flooding of houses, houses are built on stilts and above the ground level.

9. What are the controls affecting the climate of India? Explain them.

Ans.- There are six major controls of the climate of any place.

They are: latitude, altitude, pressure and wind system, distance from the sea (continentality), ocean currents and relief features.

Latitude

• Due to the curvature of the earth, the amount of solar energy received varies according to latitude.
• As a result, air temperature generally decreases from the equator towards the poles.

Altitude

• As one goes from the surface of the earth to higher altitudes, the atmosphere becomes less dense and temperature decreases.
• The hills are therefore cooler during summers.

Pressure and wind system

• The pressure and wind system of any area depend on the latitude and altitude of the place.
• Thus it influences the temperature and rainfall pattern.

Distance from the sea

• The sea exerts a moderating influence on climate.
• As the distance from the sea increases, its moderating influence decreases and the people experience extreme weather conditions.

Ocean currents

• Ocean currents along with onshore winds affect the climate of the coastal areas.
• For example, any coastal area with warm or cold currents flowing past it, will be warmed or cooled if the winds are onshore.

Relief features

• Relief too plays a major role in determining the climate of a place.
• High mountains act as barriers for cold or hot winds
• They may also cause precipitation if they are high enough and lie in the path of rain-bearing winds.
• The leeward side or opposite side of mountains remains relatively dry.

10. Explain the factors that affect India’s climate.

Ans.- Latitude

• The latitude, Tropic of Cancer passes through the middle of the country from the Rann of Kuchchh in the west to Mizoram in the east.
• Almost half of the country, lying south of the Tropic of Cancer, belongs to the tropical area.  
• All the remaining area, north of the Tropic, lies in the sub-tropics.
• Therefore, India’s climate has characteristics of tropical as well as subtropical climates.

Altitude

• India has Himalayan mountains to the north, which have an average height of about 6,000 metres.
• The Himalayas prevent the cold winds from Central Asia from entering the subcontinent.
• It is because of these mountains that this subcontinent experiences comparatively milder winters as compared to central Asia.

Pressure and Winds

The climate and associated weather conditions in India are governed by the following atmospheric conditions:

• Pressure and surface winds

• Upper air circulation

• Western cyclonic disturbances and tropical cyclones

11. Define the following terms-

• Coriolis force
• Western Cyclonic Disturbances
• Jet streams

Ans.- Coriolis force

• An apparent force caused by the earth’s rotation.
• The Coriolis force is responsible for deflecting winds towards the right in the northern hemisphere and towards the left in the southern hemisphere.
• This is also known as ‘Ferrel’s Law.

Western Cyclonic Disturbances

• The cyclone which originate over the Mediterranean Sea and western Asia, move into India along with the westerly Jet stream and bring rainfall.
• They usually influence the weather of the north and north-western regions of India in winter months.

Jet streams

• These are a narrow belt of high altitude (above 12,000 m) westerly winds in the troposphere.
• Their speed varies from about 110 km/h in summer to about 184 km/h in winter.

12. Discuss the mechanism of the monsoons in detail.

Ans.- Following are the factors responsible for the mechanism of monsoon:-

(a) The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.

(b) The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator. It is also known as the monsoon trough during the monsoon season).

(c) The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affects the Indian Monsoon.

(d) The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.

(e) The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.

13. What does the Inter Tropical Convergence Zone mean?

Ans.- Inter Tropical Convergence Zone

• The Inter Tropical Convergence Zone (ITCZ,) is a broad trough of low pressure in equatorial latitudes.
• This is where the northeast and the southeast trade winds converge.
• This convergence zone lies more or less parallel to the equator but moves north or south with the apparent movement of the sun.

14. What is El Nino?

Ans.- El Nino

• El Nino is a name given to the periodic development of a warm ocean current along the coast of Peru as a temporary replacement of the cold Peruvian current.
• ‘El Nino’ is a Spanish word meaning ‘the child’, and refers to the baby Christ, as this current starts flowing during Christmas.
• The presence of the El Nino leads to an increase in sea-surface temperatures and weakening of the trade winds in the region.

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

Ans.- 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.

16. Which part of India does experience the highest diurnal range of temperature and why?

Ans.- Diurnal range of temperature is the difference between maximum and minimum temperature of a day.

• Diurnal range of temperature is high in the deserts like Rajasthan, Thar Desert and interior parts of Rann of Kutch.
• In these sandy areas the day temperature may raise up to 50^oC and by night the temperature drops down to nearly freezing point.

17. How is the El Nino phenomenon connected with the Southern Oscillation?

Ans.- The presence of the El Nino leads to an increase in sea-surface temperatures and decrease in pressure conditions which affects the monsoons.

• Normally when the tropical eastern south Pacific Ocean experiences high pressure, the tropical eastern Indian Ocean experiences low pressure.
• But in certain years, there is a reversal in the pressure conditions and the eastern Pacific has lower pressure in comparison to the eastern Indian Ocean.
• This periodic change in pressure conditions is known as the Southern Oscillation or SO which help us to predict the intensity of the monsoons.
• The changes in pressure conditions are connected to the El Nino. Hence, the phenomenon is referred to as ENSO (El Nino Southern Oscillations).
• In the deserts like Rajasthan, Thar Desert and interior parts of Rann of Kutch, the day temperature may raise up to 50^oC and by night the temperature drops down to nearly freezing point. Give reason.
• This happens because during the day time, sand absorbs heat very fast and at the same time loses heat very fast at night.

18. Why is the monsoon considered a unifying bond?

Ans.- The subcontinent of India has great variations in the temperature conditions and the amount of rainfall.

• Nevertheless, the unifying influence of the monsoon on the Indian subcontinent is quite perceptible.
• The Indian landscape, its animal and plant life, its entire agricultural calendar and the life of the people, including their festivities, revolve around this phenomenon.
• The monsoon thus binds the entire continent, where all wait eagerly for their arrival.