Implications of the 3-cell conceptual model

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The 3-cell conceptual model is a remarkably simple model which explains most of the major features of our
atmospheric circulation, surface ocean circulation and even vegetation patterns. This week you will have a chance
to think through how the 3-cell conceptual model relates to the real world.
1. On the map on the next page draw and label the 3 cells in both hemispheres. Why does air rise at the
Equator?
2. Label the position of the ITCZ, subtropical highs, and polar highs.
3. Draw and label approximate bands on the world map where you might expect to see tropical rainforest
and desert regions. Compare your bands with the map of vegetation displayed at the front. Are there any
differences? What might cause these differences?
4. How does the 3-cell conceptual model explain the existence of:
a. The Sahara desert?
b. The Amazon rainforest?
5. Label on your diagram the polar front in both hemispheres.
a. Why do the polar jet streams form above the polar front? Which direction do they flow in each
hemisphere?
6. Lightly draw in the easterly and westerly winds in both hemispheres.
7. In the South Atlantic draw:
a. arrows to show how Ekman transport would move surface water as a result of the easterly trade
winds and westerlies.
b. the resulting “high” in sea level and how water would flow outwards creating the gyre
8. The arrow off the coast of southwestern Africa shows the prevailing wind direction. Would upwelling or
downwelling occur here? Would that result in high or low biological productivity at the coast? Why?
9. The image to the right shows Jupiter, which has several more atmospheric cells
(clearly visible) than Earth (and normal winds that blow at hurricane strength,
arrows shown). What do you think may account for such a dramatic wind
difference?