Dps-Modern Indian School, Doha, Qatar

DPS-MODERN INDIAN SCHOOL, DOHA, QATAR

CHAPTER 4: CLIMATE 1. Distinguish between weather and climate.

CLIMATE WEATHER It refers to the sum total of weather Weather refers to the state of the conditions and variations over a large atmosphere over an area at any given area for a long period of time point of time.

In comparison to weather, it is meant for In comparison to climate, it is meant for a a very long period of time much shorter period of time, i.e. to say one day, one week etc

The climatic data given are based on The weather data given are precise and averages accurate

It is meant for a larger area such as a It refers to a much smaller area, such as a country or a continent city, town or a village.

2. Define the term Monsoon a. The word Monsoon is derived from the Arabic work ‘mausim’ which literally means season. b. Monsoon refers to the seasonal reversal in the wind direction during a year.

3. Give examples from India to show that there is variation in temperature and precipitation

a. In summer, the mercury occasionally touches 50º C in some parts of the Rajasthan desert, whereas it may be around 20ºC in Pahalgam in Jammu and Kashmir b. On a winter night, temperature at Dras in Jammu and Kashmir may be as low as -45 ºC. Thiruvananthapuram on the other hand, may have a temperature of 22 ºC c. While precipitation is mostly in the form of snowfall in the upper parts of Himalayas, it rains over the rest of the country d. The annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and western Rajasthan. e. Most parts of the country receive rainfall from June to September but some parts like Tamil Nadu coast get most of its rain during October and November. 4. Distinguish between precipitation and rainfall Precipitation: a. It is the condensed water which falls from the clouds in solid or semi- solid or liquid form b. It can occur in high latitudes and in plains c. Examples are Snow, Hail, Sleet, etc

Rainfall: a. It is the falling down of condensed water from the clouds in liquid form only b. For example: a different form of rainfall is Drizzle

5. List out the six factors affecting the climate of any place. Also briefly examine each factor There are six factors affecting the climate of any place. They are: a. Latitude b. Altitude c. Pressure and wind system d. Distance from the sea (Continentality) e. Ocean currents f. Relief features

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

Altitude: (what is normal lapse rate?) a. Normal lapse rate states that temperature decreases by 1 ºC with the ascent of every 165 m b. Air near the earth’s surface is dense so it has greater capacity to observe heat in comparison to the air above it, which is thinner c. Air is heated from bottom to top by convectional currents d. Air near the earth’s surface has greater concentration of dust particles, Carbon di oxide, water vapour etc., all of which are good absorbers of heat

Pressure and Wind system a. The pressure and wind system of any area depend on the latitude and altitude of the place. b. Thus, it influences the temperature and rainfall pattern

Distance from the Sea (difference between Equable climate and continental climate) a. Areas which have coastal location will have equable climate, i.e. to say, summers are mild and winters re cool, as they are affected by both land and sea breeze. b. On the other hand, areas which are in the interior of the continents have continental type of climate which is hot in the summers and cold in winters.

Ocean Currents: a. Their influence is till the coastal areas. b. The warm current increases the temperature and brings rain c. Whereas, the cold current decreases the temperature and is most likely to bring clear weather d. Relief features: (refer to Chapter 2, Q No. 18)

6. List out the factors affecting the climate of India The factors affecting the climate of India are: a. Latitude b. Altitude c. Pressure and winds

7. What are Jet Streams? a. These are a narrow belt of high altitude (above 12000 m) westerly winds in the troposphere b. Their speed varies from about 110 km/hr in summer to about 184 km/hr in winter. c. The most constant are the mid latitude and the sub tropical jet stream

8. Briefly examine the mechanism of the south-western monsoons a. The differential heating and cooling of the 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 º N of the equator- also called the monsoon trough during the monsoon season) c. The presence of high pressure area, east of Madagascar, approximately at 20 ºS 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 high pressure over the plateau at about 9 km above sea level e. The movement of the elderly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer

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

10. What is ENSO? (El Nino Southern Oscillation)?

a. A feature connected with the southern oscillation is the El Nino, a warm ocean current that flows past the Peruvian coast, in the place of the cold Peruvian current, every 2 to 5 years. b. The changes in pressure conditions are connected to the El Nino. Hence, the phenomenon is referred to as ENSO 11. What is meant by the ‘burst’ of monsoon? Around the time of its arrival, the normal rainfall increases suddenly and continues constantly for several days. This is known as the ‘burst’ of monsoon

12. List out the various major seasons experienced by our country Four main seasons can be identified in India: the cold weather season, the hot weather season, the advancing monsoon and the retreating monsoon season.

13. Examine the characteristics of the seasons on the basis of Months, Pressure systems, Temperature and rainfall and Characteristics

Cold Weather Season: (winter) a. Months: The cold weather season begins from mid-November in northern India and stays till February b. Temperature and Rainfall: The average temperature of Chennai on the eastern coast is between 24-25 ºC while in the northern plains, it ranges between 10- 15 ºC. Some amount of rainfall occurs on the Tamil Nadu coast from these winds as they blow from sea to land c. Pressure system: In the northern part of the country, a feeble high pressure region develops, with light winds moving outwards from this area d. Characteristics: A characteristic feature of the cold weather season over the northern plains is the inflow of cyclonic disturbances from the west and the northwest. e. These low pressure systems originate over the Mediterranean Sea and western Asia and move into India along with the western flow. This phenomenon is referred to as the western disturbances.

Hot Weather Season: (summer) a. Months: as such, from March to May, it is hot weather system in India. b. Temperature: in March, the highest temperature is about 38 ºC, recorded on the Deccan Plateau. In April, temperatures in Gujarat and Madhya Pradesh are around 42 ºC c. Pressure system: Towards the end of May, an elongated low pressure area develops in the region extending from the Thar Desert in the northwest to Patna and Chota Nagpur plateau in the east and south east d. Characteristics: a. A striking feature of hot weather season is the ‘loo’. These are strong, gusty, hot and dry winds blowing during the day over the north and north-western India b. Towards the close of the summer season, pre- monsoon showers are common especially in Kerala and Karnataka. They help in the early ripening of mangoes, and are called ‘mango showers’.

Advancing Monsoon Season (the rainy season) a. Months: The advancing monsoon season is from June to September b. Pressure: At this point of time, we find the presence of the powerful low pressure trough which locates itself in north western part of India. c. Temperature and rainfall: a. Temperature remains moderate all through the year b. Rainfall is nearly wide spread all through the country d. Characteristics: A phenomenon associated with the monsoon is its tendency to have ‘breaks’ in rainfall. Thus it has wet and dry spells. In other words, the monsoon rains take place only for a few days at a time. They are interspersed with rainless intervals. These breaks in monsoon are related to the movement of the monsoon trough.

Retreating Monsoon (The Transition Season) a. Months: It occurs between October and November b. Pressure: the monsoon trough or the low pressure trough over the northern plains becomes weaker. This is gradually replaced by a high pressure system c. Temperature: the months of October to November form a period of transition from hot rain season to dry winter conditions. The retreat of the monsoons is marked by clear skies and rise in temperature d. Characteristics: owing to the conditions of high pressure and humidity, the weather becomes rather oppressive during the day. This is commonly known as ‘October Heat’. e. This shift is associated with the occurrence of cyclonic depressions, which originates over the Andaman Sea. These cyclones generally cross the eastern coasts of India and cause heavy and widespread rain.

14. Examine the distribution of rainfall in our country.

a. The western coast and the north-eastern India receive over about 400 cm of rainfall annually b. However, it is less than 60 cm in western Rajasthan and adjoining parts of Gujarat, Haryana and Punjab c. Rainfall is equally low in the interior of the Deccan plateau and east of the Sahyadris d. The rest of the country receives moderate rainfall. Snowfall is restricted to the Himalayan region

15. How do Jet Streams affect the climate of India? In the winter season, northern India receives rainfall due to western disturbances which are brought into India all the way from the Mediterranean Sea by the help of jet streams

16. Which part of India experiences the highest diurnal range of temperature and why? Rajasthan/North west part of India experiences the highest diurnal range of temperature. As these places are located in the interior of the continent, so they are only affected by winds originating from land

17. Why is the monsoon considered a unifying bond? a. Our agricultural seasons all over the country are planned keeping in mind the arrival of the south west monsoon season b. Also, many of our local traditions and folklores speak about the south west monsoon all over the country 18. Why does the rainfall decrease from the east to the west in Northern India? a. This is because of the Bay of Bengal branch of monsoon, which comes into India from the eastern side, full of moisture, giving maximum rainfall to the east. b. As it travels westward, the amount of moisture reduces with time, and by the time it reaches the western part of Northern India, it has already shed most of its moisture.

19. Why does seasonal reversal of wind take place over the Indian subcontinent? a. In the winter season, we find the presence of a strong high pressure in northern India, whereas, the surrounding water bodies have low pressure. b. So light cold winds blow from land to sea c. But, the opposite happens in the monsoon season as North West part of India has a low pressure trough which attracts the south west monsoon winds from the surrounding water bodies.

20. Why does the Tamil Nadu coast receive winter rainfall? OR Why does the Coromandal coast receive winter rainfall? a. It is observed that Tamil Nadu does not lay in the path of the south west monsoon winds. b. But it is only in winter that it receives rainfall from the North East trade winds which pick up moisture from the Bay of Bengal and then, are deflected towards the Tamil Nadu coast.

21. Why is the delta region of the eastern coast frequently struck by cyclones? This shift is associated with the occurrence of cyclonic depressions, which originate over the Andaman Sea. These cyclones generally cross the eastern coasts of India and cause heavy and wide spread rain. That is why the delta region of the eastern coast is frequently struck by cyclones.

22. Why are parts of Rajasthan, Gujarat and the leeward side of the Western Ghats is drought prone? a. It is observed that Rajasthan, Gujarat lie at the end of the part of Bay of Bengal current and Arabian Sea current. So, when these branches reach these places, they hardly have any moisture left with them. b. The leeward side of the Western Ghats hardly receives any rainfall as most of the moisture has been shed in the windward side.

23. What is a climatic divide? How do the Himalayas act as a climatic divide? A climatic divide is a physical barrier or boundary which distinguishes the climate of one region from another. The Himalayas act as a climatic divide because: a. It protects the Indian subcontinent from the chilly northern winds. b. It is because of these mountains that India enjoys a tropical climate. c. These mountains force the monsoon winds to shed their moisture in India causing a lot of rain in India. d. It is because of Himalayas that the temperature differences are minimised between the tropical and sub-tropical India.