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Air in motion · 5 min · 4 steps

The monsoon year

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Goal. Explain why the wind over Taiwan and India reverses between winter and summer.

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Steps

  1. Predict

    In January, which way does the average wind blow over Taiwan?

    • From the north-east
    • From the south-west
    • There is no regular pattern
    Show the answer

    From the north-east. From the north-east: cold, dry air flowing out of Siberia and Mongolia.

    January average, 1991–2020. In winter the continent is far colder than the ocean. Cold, heavy air builds a huge high-pressure area over Siberia and Mongolia, and wind flows out of it: Taiwan's north-east monsoon.

  2. July average. Now the land is hotter than the sea. Air rises over Asia and moist air flows in from the oceans: the south-west monsoon, which brings heavy summer rain to southern China and Taiwan.

  3. Over India the reversal is even stronger. The summer monsoon brings most of India's yearly rain between June and September.

  4. Taipei's card shows its typical year. In winter the north-east monsoon brings cool, damp, cloudy days to northern Taiwan, while the Central Mountain Range shelters the south-west, so Kaohsiung's winters are sunnier and drier.

The common mistake

Myth

Monsoon means heavy rain.

Fact. Monsoon means a seasonal reversal of the wind. The rainy season comes with the summer monsoon; the winter monsoon is dry over most of Asia, although it brings drizzle to windward coasts such as northern Taiwan.

Check yourself

Question 1

What makes the monsoon wind reverse?

  • The Moon's orbit
  • Land heats and cools faster than the sea
  • Ocean currents changing direction
Show the answer

Land heats and cools faster than the sea. In summer the land is hotter than the sea and air flows in from the ocean; in winter the land is colder and the flow reverses.

Question 2

In which season does Taiwan get the south-west monsoon?

  • Winter
  • Summer
  • Never
Show the answer

Summer. The south-west monsoon arrives in summer and brings moist air and heavy rain.

Question 3

Why are Kaohsiung's winters drier than Taipei's?

  • It is closer to the equator
  • The mountains shelter it from the north-east monsoon
  • It is far from the sea
Show the answer

The mountains shelter it from the north-east monsoon. The Central Mountain Range blocks the moist north-east wind, which drops its rain on the north and east sides of the island.

Words in this lesson

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Curriculum

Taiwan 12-year curriculum (108 課綱), natural science
Ib-Ⅳ-6 · Ib-Ⅳ-2
US Next Generation Science Standards
MS-ESS2-6
England national curriculum
KS3 Geography: weather and climate