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Chapter 4Global Climate and Biomes
Earth
Regions near the equator (0o) receive light at 90o
High latitudes receive light at low angles
1.Sun rays travel shorter distance to equator (energy is lost the farther it travels)2.Sun rays distributed over smaller area (more concentrated)3.Albedo
Unequal Heating of the Earth
Solar energy is concentrated near the equator
Image: Netherlands Center for Climate Research
Ene
rgy
90 45 0 45 90Latitude
absorbed solar energy
Ene
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90 45 0 45 90Latitude
absorbed solar energy
Emitted IR energy
Ene
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90 45 0 45 90Latitude
absorbed solar energy
Emitted IR energy
More energy is absorbed near the equator than emittedAnd more energy is emitted near the poles than is absorbed.
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90 45 0 45 90Latitude
net radiation surplus
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90 45 0 45 90Latitude
net radiation surplus
net radiationdeficit
Excess energy at the equator is transferred towards the poles by convection cells
Solar energy received is greatest near the equator.
Energy is moved from the equator to the poles.
Solar energy received is greatest near the equator.
Energy is moved from the equator to the poles.
Energy is transferred by wind and ocean currents
Solar Energy
Air near the equator is warmed, and rises
sola
r ra
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tion
Hadley Circulation Cell
The rising air creates a circulation cell, called a Hadley Cell
sola
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L
H
H
Rising air low pressureSinking air high pressure
Hadley Circulation Cell
H
Warm air rises
Rising air is replaced
Hadley Circulation Cell
Warm air rises
Air cools, sinks
Rising air is replaced
Hadley Circulation Cell
Warm air rises
Air cools, sinks
Rising air is replaced
LOW HIGH HIGH
Hadley Circulation Cell
Warm air rises
Air cools, sinks
Rising air is replaced
LOW HIGH HIGH
Rising air cools; the air’s capacity to hold water drops. Rain!
No rain inregionswhereair isdescending
The Coriolis Effect
• Rotation of the Earth leads to the Coriolis Effect
• This causes winds (and all moving objects) to be deflected:– to the right in the Northern
Hemisphere
– to the left in the Southern Hemisphere
What makes Venus different?
The Coriolis Effect
Based on conservation of angular momentum
We experience linear momentum when we are in a car that is traveling fast and then stops suddenly.
Planet Earth rotates once per day.
Objects near the poles travel slower than those near the equator.
Objects near the poles have less angular momentum than those near the equator.
When objects move poleward, their angular momentum causes them to go faster than the surrounding air. Conversely, they slow as they move towards the equator.
When objects move north or south, their angular momentum causes them to appear to go slower or faster.
This is why traveling objects (or air parcels) deflect to the right in the northern hemisphere and to the left in the southern hemisphere.
