LIWA

Climate

ICSE Class 10 · Geography · Chapter 5

What this chapter covers

Key points

Questions answered

Distinguish between weather and climate.
Weather is the state of the atmosphere at a place at a particular time and can change within hours. Climate is the average weather of a large area over a long period, usually 30 years or more.
Why is the climate of India called a tropical monsoon type of climate?
Most of India lies in or close to the tropics, and its climate is controlled by the monsoon, a seasonal reversal of winds that brings a wet season from June to September and a mainly dry season for the rest of the year.
Explain how the Himalayas influence the climate of India in winter and in summer.
In winter they block the cold, dry winds from Central Asia, keeping northern India warmer. In summer they stop the moist south-west monsoon winds from crossing into Tibet and force them to rise and shed their rain over India.
Give two reasons why Mumbai has a smaller annual range of temperature than Delhi.
Mumbai lies on the coast, so the sea moderates its temperature, while Delhi lies far inland and has a continental climate. Mumbai is also farther south, so its winters are warmer.
What are jet streams? Name the two jet streams that affect India and state one effect of each.
Jet streams are narrow bands of very fast winds in the upper troposphere. The sub-tropical westerly jet brings western disturbances into north-west India in winter; the tropical easterly jet over the peninsula in summer is linked with the burst of the monsoon.
How does El Nino affect the Indian monsoon?
El Nino warms the central and eastern Pacific, which changes pressure patterns over the Indian Ocean. The monsoon winds weaken and India often receives below-normal rain or drought.
Explain how the south-west monsoon winds get their direction.
When the ITCZ moves north in summer, the south-east trade winds are drawn across the equator. The Earth's rotation deflects them to the right in the northern hemisphere, so they blow from the south-west.
Why does the Malabar coast receive much more rain than the Deccan Plateau in the south-west monsoon?
The Malabar coast lies on the windward side of the Western Ghats, where the Arabian Sea branch rises and gives heavy orographic rain. The Deccan Plateau lies on the leeward side in the rain-shadow, where the winds descend and become dry.

Past board exam questions

ICSE 2027 sample paper · 1 mark

The place that is likely to experience less rainfall from June to September is:

  1. Kochi
  2. Goa
  3. Mumbai
  4. Chennai
Show answer
Chennai

ICSE 2027 sample paper · 2 marks

(a) Why does monsoon begin to retreat after September? (b) Which is the first state to receive rain from the South-West monsoon winds?

Show answer
(a) After September the apparent southward migration of the sun cools the Indian landmass, so air pressure over the land rises. The monsoon trough (low pressure) weakens and the south-west monsoon winds begin to withdraw. (b) Kerala.

ICSE 2027 sample paper · 2 marks

Name the branch of South-West Monsoon wind, that brings rain to each of the following regions: (a) Windward slope of Khasi Hills (b) Western slopes of Western Ghats

Show answer
(a) Bay of Bengal branch. (b) Arabian Sea branch.

ICSE 2027 sample paper · 3 marks

Give a reason for each of the following: (a) Interior parts of the Deccan Plateau receive low annual rainfall. (b) The hills of peninsular India are devoid of snow. (c) It is difficult to hold a cricket match in Chennai in the winter season.

Show answer
(a) The interior Deccan lies in the rain-shadow (leeward side) of the Western Ghats; the moist Arabian Sea branch winds shed their moisture on the windward slopes and are dry by the time they descend into the plateau (and the Bay of Bengal branch runs parallel to the east coast, giving little rain here). (b) The hills of peninsular India are low in elevation and lie in the tropics, so temperatures never fall low enough for snowfall. (c) Chennai on the Coromandel (east) coast gets most of its rain in winter (October–December) from the retreating / North-East monsoon winds, which pick up moisture over the Bay of Bengal; outdoor matches are likely to be washed out.

ICSE 2027 sample paper · 3 marks

Study the climatic data of station X and answer the questions that follow: | Months | Jan | Feb | Mar | Apr | May | June | July | Aug | Sep | Oct | Nov | Dec | |---|---|---|---|---|---|---|---|---|---|---|---|---| | Temperature (ºC) | 9 | 16.5 | 24.3 | 30.4 | 35.2 | 33.8 | 27.2 | 28.4 | 27.1 | 22 | 16.4 | 10.7 | | Rainfall (cm) | 15 | 12.9 | 4.7 | 4.9 | 11.4 | 61.7 | 240 | 261 | 124 | 55.8 | 1.2 | 9.9 | (a) In which month does the station receive maximum rainfall? (b) Calculate the annual range of temperature. (c) Why do you think the temperature drops significantly in the month of July?

Show answer
(a) August (261 cm). (b) Annual range = highest − lowest monthly temperature = 35.2 °C (May) − 9 °C (January) = 26.2 °C. (c) The onset of the South-West monsoon in July brings heavy rain and cloud cover, which lowers the average temperature.

ICSE 2026 sample paper · 1 mark

On the outline map of India provided: Mark with arrows and name the wind which brings rainfall to the Konkan coast.

Show answer
Draw arrows from the Arabian Sea blowing from the south-west onto the Konkan coast and label them 'South-West Monsoon (Arabian Sea branch)'.

ICSE 2026 board paper · 1 mark

Mawsynram, the rainiest place in the world, gets the rain from:

  1. South-west monsoon wind - Arabian Sea branch
  2. South-west monsoon wind - Bay of Bengal branch
  3. Western Disturbance
  4. North-east monsoon wind
Show answer
South-west monsoon wind - Bay of Bengal branch

ICSE 2026 sample paper · 1 mark

The Himalayas have a significant impact on the climate of India as they:

  1. block the N.E. monsoon winds.
  2. cause rainfall in the Gangetic plains.
  3. create a rain shadow area in the Deccan plateau.
  4. cause cyclonic disturbance in the Bay of Bengal.
Show answer
cause rainfall in the Gangetic plains.