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?
(b) Mawsynram
(ii) The wind blowing in the northern plains in summer is known as:
(b) Loo
(iii) Which one of the following causes rainfall during winters in the northwestern part of India?
(c) Western disturbances
(iv) Monsoon arrives in India approximately in:
(c) Early June
(v) Which one of the following characterises the cold-weather season in India?
(b) Warm days and cold nights
2. Answer the following questions briefly:
(i) What are the factors affecting the climate of India?
Ans: The factors affecting India’s climate are:
Latitude
Altitude
Pressure and Winds
(ii) Why does India have a monsoon type of climate?
Ans: India experiences a monsoon type of climate due to the seasonal reversal of winds, where the weather conditions change from season to season, particularly in the interior regions. The monsoon winds significantly influence temperature and rainfall patterns, with the monsoon lasting from early June to mid-September.
(iii) Which part of India experiences the highest diurnal range of temperature and why?
Ans: The northwestern part of India, particularly the Thar desert, experiences the highest diurnal range of temperature due to the lack of an ocean to moderate the temperature.
(iv) Which winds account for rainfall along the Malabar Coast?
Ans: Southwest monsoon winds account for rainfall along the Malabar Coast.
(v) What are Jet streams, and how do they affect the climate of India?
Ans: Jet streams are high-altitude winds (above 12,000 meters) that flow from the west at high speeds (110-184 km/h). They influence the Indian monsoon by causing depressions during the season and are associated with shifts in weather patterns.
(vi) Define monsoons. What do you understand by “break” in monsoon?
Ans: Monsoons are seasonal winds that change direction. A “break” in the monsoon occurs when the monsoon trough moves north or south, causing dry spells in some areas and heavy rainfall in others.
(vii) Why is the monsoon considered a unifying bond?
Ans: The monsoon unites India as it impacts the entire country, bringing water crucial for agriculture. It affects the entire landscape, agricultural cycles, and the lives of people, creating a shared rhythm across the nation.
3. Why does the rainfall decrease from the east to the west in Northern India?
Ans: The rainfall decreases from east to west as the monsoon winds lose moisture as they travel westward.
4. Give reasons as to why:
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent?
Ans: Due to pressure differences between land and sea.
El Niño also influences this reversal.
(ii) The bulk of rainfall in India is concentrated over a few months.
Ans: The Southwest Monsoon brings rapid rainfall across large parts of the country, mainly from June to September.
(iii) The Tamil Nadu coast receives winter rainfall.
Ans: Due to the Northeast Monsoon, which brings rainfall to this region during the winter months.
(iv) The delta region of the eastern coast is frequently struck by cyclones.
Ans: The Bay of Bengal experiences frequent pressure changes, making the region prone to cyclones.
(v) Parts of Rajasthan, Gujarat, and the leeward side of the Western Ghats are drought-prone.
Ans: These regions fall in the rain shadow of the Aravalli Mountains, leading to limited rainfall.
5. Describe the regional variations in the climatic conditions of India with the help of suitable examples:
Ans: Cold weather season:The cold season starts in mid-November in northern India, with December and January being the coldest months.
Chennai has an average temperature of 24-25°C, while in the northern plains, it is around 10-15°C.
Frost is common in the north, and the Himalayan slopes experience snowfall.
Hot weather season:In March, the temperature reaches 38°C on the Deccan Plateau, rising to 42°C in April in Gujarat and Madhya Pradesh. By May, temperatures in northwestern India can reach 45°C.
In peninsular India, temperatures remain lower due to the moderating effect of the sea.
6. Discuss the mechanisms of the monsoon:
Ans: Differential heating of land and water creates low pressure over land and high pressure over seas.
Shift of the Inter Tropical Convergence Zone (ITCZ) over the Ganga Plain during summer.
High-pressure area over the Indian Ocean east of Madagascar affects the Indian monsoon.
Intense heating of the Tibetan Plateau leads to low pressure, resulting in vertical air currents.
The movement of the westerly jet stream and the presence of the tropical easterly jet stream over India influence the monsoon.
7. Give an account of weather conditions and characteristics of the cold season:
Ans: The cold season starts in mid-November in northern India and lasts until February.
December and January are the coldest months, with temperatures in Chennai around 24-25°C, and in the northern plains, between 10°C and 15°C.
The northeast trade winds prevail, bringing dry conditions to most parts of the country. Some rainfall occurs on the Tamil Nadu coast due to these winds.
Cyclonic disturbances from the Mediterranean Sea bring winter rains and snowfall in the mountains, contributing to rabi crop cultivation
8. Give the characteristics and effects of the monsoon rainfall in India:
Ans: Monsoon rainfall lasts for 100-120 days, from early June to mid-September.
The monsoon burst brings sudden, heavy rainfall.
The Arabian Sea and Bay of Bengal branches of the monsoon arrive in June, with the Bay of Bengal branch reaching Assam first and the Arabian Sea branch reaching Mumbai later.
The monsoon merges over the northwestern Ganga Plains by mid-June, covering the rest of the country by mid-July.