Chapter 4 Global Climate and Biomes

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

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absorbed solar energy

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absorbed solar energy

Emitted IR energy

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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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net radiation surplus

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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

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Hadley Circulation Cell

The rising air creates a circulation cell, called a Hadley Cell

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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.