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Lessons / Climate

Climate · 5 min · 4 steps

The sea effect

Plays here

Goal. Use two cities' typical years to show how the sea narrows the gap between summer and winter.

Steps

  1. Predict

    Vancouver and Winnipeg are both near 50° N. Which has the bigger gap between summer and winter?

    • Vancouver, on the Pacific coast
    • Winnipeg, in the middle of the continent
    • About the same
    Show the answer

    Winnipeg, in the middle of the continent. Winnipeg: its typical July is about 36 °C warmer than its January. Vancouver's gap is about 14 °C.

    Vancouver's typical year: mild, wet winters and cool summers, with the Pacific Ocean next door.

  2. Now compare it with Winnipeg, about 1,900 km further east in the middle of the continent, at almost the same latitude. Same Sun angle, very different year.

  3. Water needs four to five times more heat than dry soil or rock to warm by the same amount, and the sea mixes heat deep down. So the ocean warms and cools slowly, and the westerly wind carries its mild air over Vancouver. The Coast Mountains and the Rockies keep most of it from Winnipeg.

  4. The extreme case: Yakutsk in Siberia, far from any open sea, swings by nearly 60 °C between January and July.

The common mistake

Myth

Places at the same latitude have the same climate.

Fact. Latitude sets how much sunlight arrives, but distance from the sea, the prevailing winds and height above sea level change the climate a great deal.

Check yourself

Question 1

Why does the sea keep coastal winters mild?

  • It stores summer heat and releases it slowly
  • It stays at 20 °C all year
  • Salt water produces heat
Show the answer

It stores summer heat and releases it slowly. The sea's large heat capacity and mixing let it store summer heat and give it back through the winter.

Question 2

Lisbon is on the Atlantic coast and Madrid is in the centre of Spain. Which has the larger yearly range?

  • Lisbon
  • Madrid
  • About the same
Show the answer

Madrid. Madrid's typical range is about 21 °C and Lisbon's about 10 °C, although they lie at almost the same latitude.

Question 3

Kaohsiung's yearly range is small, about 10 °C. What is the main reason?

  • It is by the sea and inside the tropics
  • It is high in the mountains
  • It is far inland
Show the answer

It is by the sea and inside the tropics. Kaohsiung lies just inside the tropics, so the Sun stays high all year. The nearby sea evens out the rest.

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Curriculum

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