IB Environmental systems and societies Topic 6.1B Tricellular Model of Atmospheric Circulation Revision Notes (SL/HL)

IB Environmental systems and societies Topic 6.1B Tricellular Model of Atmospheric Circulation Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Uneven Heating Sets the Atmosphere in Motion

Definition

Tricellular Model of Atmospheric Circulation

The tricellular model of atmospheric circulation explains the global movement of air and how it influences temperature, precipitation, and the distribution of biomes.

Earth receives uneven heating from the Sun because sunlight strikes different latitudes at different angles.
The equator receives direct, concentrated radiation, strongly warming the surface and the air above it.
The poles receive sunlight at a low angle, spreading the same energy over a larger area, so they stay much cooler.
This unequal heating creates pressure differences that set the atmosphere moving in a global circulation called the tricellular model.
This circulation moves heat from the equator toward the poles, helping to balance global temperatures.

Analogy

The atmosphere works like a giant conveyor belt.
It carries heat from the equator toward the poles and returns colder air to the equator.
This constant movement stops the equator overheating and the poles from getting even colder.

Why the Equator Runs an Energy Surplus

Earth is spherical, so sunlight strikes the equator more directly than the poles.
Tropical regions absorb far more solar radiation than polar regions.
Snow and ice at the poles have high albedo, reflecting much of the incoming radiation.
Between about 38°N and 38°S, heat gained exceeds heat lost, creating an energy surplus.
At higher latitudes, heat lost exceeds heat gained, creating an energy deficit.
Atmospheric circulation develops to move this surplus energy poleward and even out the contrast.

Tip

Link differential heating to both latitude and solar angle.
Do not confuse it with seasons, which come from the tilt of Earth's axis.

The Tricellular Model: Three Cells per Hemisphere

The model divides each hemisphere into three large circulation cells:
1. the Hadley cell

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Uneven Heating Sets the Atmosphere in Motion

Definition

Tricellular Model of Atmospheric Circulation

The tricellular model of atmospheric circulation explains the global movement of air and how it influences temperature, precipitation, and the distribution of biomes.

Earth receives uneven heating from the Sun because sunlight strikes different latitudes at different angles.
The equator receives direct, concentrated radiation, strongly warming the surface and the air above it.
The poles receive sunlight at a low angle, spreading the same energy over a larger area, so they stay much cooler.
This unequal heating creates pressure differences that set the atmosphere moving in a global circulation called the tricellular model.
This circulation moves heat from the equator toward the poles, helping to balance global temperatures.

Analogy

The atmosphere works like a giant conveyor belt.
It carries heat from the equator toward the poles and returns colder air to the equator.
This constant movement stops the equator overheating and the poles from getting even colder.

Why the Equator Runs an Energy Surplus

Earth is spherical, so sunlight strikes the equator more directly than the poles.
Tropical regions absorb far more solar radiation than polar regions.
Snow and ice at the poles have high albedo, reflecting much of the incoming radiation.
Between about 38°N and 38°S, heat gained exceeds heat lost, creating an energy surplus.
At higher latitudes, heat lost exceeds heat gained, creating an energy deficit.
Atmospheric circulation develops to move this surplus energy poleward and even out the contrast.

Tip

Link differential heating to both latitude and solar angle.
Do not confuse it with seasons, which come from the tilt of Earth's axis.

The Tricellular Model: Three Cells per Hemisphere

The model divides each hemisphere into three large circulation cells:
1. the Hadley cell

Definition

Paywall

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Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 6.1B Tricellular Model of Atmospheric Circulation Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Uneven Heating Sets the Atmosphere in Motion

Why the Equator Runs an Energy Surplus

The Tricellular Model: Three Cells per Hemisphere

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Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Uneven Heating Sets the Atmosphere in Motion

Why the Equator Runs an Energy Surplus

The Tricellular Model: Three Cells per Hemisphere

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account