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Climate

Chapter 26

Modern Earth Science

26.1 Factors That Affect Climate

climate the average weather conditions in an area over a long period of time

Temperature Range: the difference between the

highest and lowest temperatures of a month Precipitation: The average amount of rainfall an

area can acquire over a year The climate of a region can also be affected by the

– Latitude of a region – Heat absorption and release – Topography – Winds – Ocean currents

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Latitude

Latitude is the distance from the equator. Latitude determines the amount of

solar energy received, and the prevailing winds of a region The higher the latitude of an area

is, the smaller the angle at which the sun’s rays hit Earth is and the smaller the amount of solar energy received by the area is.

Solar Energy

Because Earth’s axis is tilted, the angle at which the sun’s rays hit an area changes as Earth orbits the sun.

Equatorial regions: 12 hours day & night with steady high temperatures.

Polar regions: large variation of daylight hours, steady low temperatures.

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Wind Patterns

Latitude determines global winds

Winds affect humidity, precipitation, temperature, & cloud cover.

Different prevailing winds = different climate

Global winds also affected by ocean currents & major mountain ranges.

Heat Absorption & Release

specific heat the quantity of heat required to raise the temperature of 1 gram of a substance 1°C

Even if not in motion, water warms more

slowly than land does. Water also releases heat energy more

slowly than land does.

Heat Absorption & Release 2

Land heats faster than water and thus can reach higher temperatures in the same amount of time.

Waves, currents, and other movements continuously replace warm surface water with cooler water from the ocean depths.

In turn, the temperature of the land or ocean influences the amount of heat that the air above the land or ocean absorbs or releases.

The temperature of the air then affects the climate of the area.

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Ocean Currents

Water moves around the globe – LAND DOESN’T

The temperature of ocean currents that come in

contact with the air influences the amount of heat absorbed or released by the air.

The temperature of the air moving ONTO SHORE is affected by the temperature of the ocean/water it comes into contact with

Seasonal Winds

monsoon a seasonal wind that blows toward the land in the summer, bringing heavy rains, and that blows away from the land in the winter, bringing dry weather

Temperature differences between the land and the

oceans sometimes cause winds to shift seasonally in some regions.

Monsoon climates, such as that in southern Asia, are caused by heating and cooling of the northern Indian peninsula.

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Topography

Elevation The surface features of the land, or topography,

also influences climate.

The elevation, or height of landforms above sea level, produces distinct temperature changes.

Temperature generally decreases as elevation increases.

More Topography

Rain Shadows When a moving air mass encounters a mountain

range, the air mass rises, cools, and loses most of its moisture through precipitation.

As a result, the air that flows down the other side of the range is usually warm and dry. This effect is called a rain shadow.

One type of warm, dry wind that forms in this way is a foehn (FAYN), a dry wind that flows down the slopes of the Alps.

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26.2 Climate Zones

Climate Zones

3 Major Climate Zones – Polar Climate

– Middle-latitude Climate

– Tropical Climate

Tropical Climate

3 Tropical Climates – Desert

– Rain Forest

– Savanna

Rain Forest

Savanna

Desert

Tropical

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Polar Climate

2 Polar Climates – Subarctic

Severe winters & short summers

Canada

– Tundra No trees, very dry, cold

air with little precipitation

Northern Alaska

Tundra

Subarctic

Polar

Middle-Latitude Climate

5 Climates – Desert & Steppe

Eastern Montana

– Mediterranean Most of California

– Marine West-Coast Seattle

– Humid Sub-tropical Georgia

– Humid Continental Iowa

Humid Sub-tropical

Humid Continental

Marine West-Coast

Mediterranean

Desert & Steppe

Middle- Latitude

US: The Middle Latitude Climate

Marine West Coast Climate

Mediterranean

Middle Latitude Steppe

Middle Latitude Desert

Humid Continental

Humid Subtropical

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Tropical Rain Forest

Warm & humid

Near the equator (5 - 10° north & south)

Dense, rain-forest vegetation

Annual rainfall more than 250 cm

Yearly temp. range only about 3° C

Amazon River basin, parts of Central America & Southeast Asia

Tropical Desert

Tropical Savanna

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Polar Climates

Subarctic

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Tundra

Middle-Latitude Climates

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