GeographyISC Class 11 · Atmospheric Pressure and Winds

Periodic and Local Winds (ISC Class 11 Geography)

Updated 17 October 2026 · Fact-checked

Periodic winds reverse with season or time of day: monsoons, land and sea breezes, mountain and valley breezes. Local winds arise from local heating and relief: loo, chinook, foehn, mistral, bora, sirocco and harmattan. The chinook and foehn are warm dry downslope winds heated by compression.

Notice that the wind always blows at the surface from the cooler, higher-pressure side to the warmer, low-pressure side, so the direction reverses at night.

Illustration drawn for QuestionBuddy.

Understand Periodic and Local Winds

Periodic winds.

Monsoons: seasonal reversal. In summer a low over north-west India draws moist south-west winds from the Indian Ocean; in winter a high over the land sends dry north-east winds outward.
Land and sea breezes: by day land heats faster so a cool sea breeze blows ashore; by night a land breeze blows out to sea.
Mountain and valley breezes: by day slopes heat and air rises up the valley (valley breeze, anabatic); by night cold dense air drains downslope (mountain breeze, katabatic).

Local winds.

Loo: hot, dry, dusty westerly of northern Indian plains in May and June afternoons.
Chinook (Rockies) and Foehn (Alps): warm, dry winds descending leeward slopes, heated by compression; the chinook melts snow quickly (snow eater) and helps grazing.
Mistral (Rhone valley) and Bora (Adriatic): cold, strong winds blowing from mountains towards the Mediterranean.
Sirocco: hot dusty wind from the Sahara across the Mediterranean.
Harmattan: dry dusty north-east wind from the Sahara over West Africa, called the doctor because it relieves humid heat.

Link to pressure. All arise from differences in heating and pressure between neighbouring places.

Periodic and Local Winds: key facts

Periodic winds: Monsoon
Land and sea breeze
Mountain and valley breeze
Warm local winds: $L oo ∣ C hin oo k ∣ F oe hn ∣ S i r occo ∣ H a r ma tt an$
Cold local winds: $M i s t r a l ∣ B or a$
Day and night: Sea breeze by day, land breeze at night | Valley breeze by day, mountain breeze at night

How to answer Periodic and Local Winds questions

Expect definition plus place and cause for each wind (3 to 4 marks).

1State whether the wind is periodic or local.
2Give the cause (heating, pressure or relief).
3Name the region and effect.
4Add a contrast, for example hot versus cold.

Periodic and Local Winds in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Evening on the coast

Suppose a beach town feels cool air from the sea in the afternoon and from the land at night.

Name each wind and the reason for the afternoon one.

Try it first, then show the solutionSolution

By day land heats faster and rises, so cooler sea air moves in: sea breeze.
By night land cools faster, so the breeze reverses: land breeze.

Answer: Sea breeze by day; land breeze at night.

Memory hook: Day sea, night land.

Snow eater

Suppose a warm dry wind blows down the leeward side of a mountain and snow melts within hours.

Name the wind and the cause of warmth.

Try it first, then show the solutionSolution

It is the chinook in the Rockies.
Descending air is heated by compression.

Answer: Chinook; compression heating.

Memory hook: Falling air warms.

Tricks to remember Periodic and Local Winds

Short memory aids. Say each one aloud once, then use it on a question the same day.

Hot loo, cool mistral
Loo in India is hot; Mistral and Bora are cold.
Use it when: Contrast.
Anabatic up, katabatic down
Anabatic climbs, katabatic comes down.
Use it when: Mountain-valley winds.

Periodic and Local Winds: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Wind identification · 1 mark · MCQBoard level

A hot, dry wind blowing over the northern plains of India in summer afternoons is the:
(a) chinook
(b) loo
(c) mistral
(d) foehn

Try it first, then show the solutionSolution

Indian local wind.

Answer: (b) Loo.

Example 2: Land and sea breeze · 2 marks · Short answerBoard level

Explain in two lines why a sea breeze blows by day.

Try it first, then show the solutionSolution

Land heats faster than sea in the day.
Air rises over land and cooler sea air moves in.

Answer: Land heats faster, so air rises there and sea air blows in.

Example 3: Chinook · 4 marks · Long answerHarder board level

Why is the chinook warm and dry, and why is it called the snow eater?

Try it first, then show the solutionSolution

It descends the leeward slopes of the Rockies.
Descending air is compressed and heated and has lost its moisture on the windward side.
The warm dry air melts snow quickly.
It also helps grazing by exposing grass.

Answer: Compression heats descending dry air that melts snow rapidly.

Example 4: Periodic comparison · 4 marks · Long answerHarder board level

Distinguish between valley breeze and mountain breeze on time, direction and cause.

Try it first, then show the solutionSolution

Valley breeze blows by day; mountain breeze at night.
Valley breeze moves up the slope; mountain breeze down.
Day slopes heat so air rises; night slopes cool so dense air drains.
Names: anabatic and katabatic.

Answer: Valley breeze: day, up-slope, heating; mountain breeze: night, down-slope, cold drainage.

Example 5: Wind in context · 5 marks · Case-basedHOTS / competency

Case: A traveller crosses from the Rhone valley to the Sahara coast. (a) Name the cold local wind she may meet. (b) Name the hot dusty wind across the Mediterranean. (c) Name the West African dry wind called the doctor and give the reason.

Try it first, then show the solutionSolution

(a) Mistral.
(b) Sirocco.
(c) Harmattan, because it relieves humid heat.

Answer: (a) Mistral (b) sirocco (c) harmattan, relieving humid heat.

Where students lose marks in Periodic and Local Winds

The slips examiners see most often, and what to write instead.

Mistake: Calling the chinook cold
Warm and cold winds are mixed.
Do this: Chinook and foehn are warm and dry; mistral and bora are cold.
Usually costs: 1 mark.
Mistake: Reversing land and sea breeze times
Day and night swapped.
Do this: Sea breeze by day; land breeze at night.
Usually costs: 1 mark.
Mistake: Naming the loo for the south
Region error.
Do this: Loo is in northern India in May-June.
Usually costs: 1 mark.

Exam tips

Name the region of each local wind.
Give cause plus effect.
Use anabatic and katabatic.
Contrast hot and cold local winds.

Practice questions on Periodic and Local Winds

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
The Bora blows near:
(a) Rhone valley
(b) Adriatic coast
(c) West Africa
(d) the Rockies
Hint
Adriatic.
Answer
(b) Adriatic coast.
Q2 · 3 marks · Short answerHarder board level
Explain the cause of the summer monsoon winds over India.
Hint
Low over land.
Answer
Intense heating creates a low over north-west India, drawing moist south-west winds from the Indian Ocean.
Q3 · 4 marks · Long answerHarder board level
Compare loo and chinook on origin, temperature and effect.
Hint
Plains versus mountains.
Answer
Loo: hot, dry, dusty westerly of the northern Indian plains in May-June afternoons. Chinook: warm, dry downslope wind of the Rockies heated by compression; it melts snow and helps grazing.
Q4 · 3 marks · Short answerHarder board level
Why does a winter high pressure over land send dry winds out in the monsoon region?
Hint
Outward flow.
Answer
In winter the land is cold and a high forms; winds blow outward from high pressure as dry north-east winds.
Q5 · 4 marks · Case-basedHOTS / competency
Case: A hill farmer notes cool air flowing down the slope at dusk. (a) Name the wind. (b) Explain its cause. (c) Say what happens to valley bottoms.
Hint
Katabatic.
Answer
(a) Mountain breeze (katabatic). (b) Slopes cool at night, air becomes dense and drains downslope. (c) Valley bottoms become coldest, forming frost pockets.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Harmattan blows over?Show answer
West Africa.
2.Sirocco source?Show answer
Sahara.
3.Foehn is in?Show answer
The Alps.
4.Mistral blows from?Show answer
The Rhone valley.
5.Valley breeze type?Show answer
Anabatic.

Periodic and Local Winds: frequently asked questions

Why is the chinook called the snow eater?

It melts snow quickly.

Are monsoons periodic?

Yes, they reverse with the season.

Why is the harmattan called the doctor?

It relieves humid heat.