Chapter 18 – Climate and Climate Change

18 – 1 What Causes Climate?

Weather refers to the condition of the atmosphere at a given time and place.

• Climate is the average year-after-year pattern of temperature, precipitation, wind and cloud cover in an area.

Factors affecting temperature include latitude, altitude, distance from large bodies of water and ocean currents.

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LATITUDE

• FOR THE MOST PART, LOCATIONS FARTHER FROM THE EQUATOR (NORTH OR SOUTH OF 00 LATITUDE) ARE COOLER THAN AREAS CLOSER TO THE EQUATOR.

EARTH’S TEMPERATURE ZONES

• Tropical Zones are areas near the equator, between 23.5 degrees north latitude and 23.5 degrees south latitude.

• Direct sunlight and warm year round.• Polar Zones are areas that extend north from 66.5 degrees to

90 degrees both north and south.• Less direct sunlight and cold climates.• Temperate Zones are between tropical and polar zones.

Between 23.5 degrees and 66.5 degrees both north and south.• Seasonal climates are experienced in both northern and

southern hemispheres. Warm or hot in summer and cool or cold in winter.

EARTH’S TEMPERATURE ZONES

ALTITUDE• For every 1 KM increase in troposphere altitude

temperature drops 6.5 degrees Celsius.• No matter what latitude, higher altitudes have

cooler climates• In the case of high mountains, altitude is a more

important factor than latitude

DISTANCE FROM LARGE BODIES OF WATER

• Marine climates are experienced in coastal regions and have warmer winters and cooler summers as water heats and cools more slowly than land.

Continental climates are experienced by the centers of N. America and Asia and have more extreme

temperatures in winter and summer than marine climate regions.

OCEAN CURRENTS

• The surface of the water warms or cools the air above it. The warmed or cooled air then moves over nearby land affecting the temperatures there.

• http://www.fastcodesign.com/1669361/better-than-a-van-gogh-nasa-visualizes-all-the-worlds-ocean-currents

• http://www.flickr.com/photos/gsfc/7009056027/

FACTORS AFFECTING PRECIPITATION

• Prevailing Winds – The wind carries air that is warm or cool, dry or humid. Where the wind comes from determines the temperature and precipitation of an area

Mountain Ranges

• The windward side of a mountain gets the majority of precipitation.

• The leeward side of a mountain lies in a rain or snow shadow and tends to be cool and dry.

MICROCLIMATES

• A small area with specific climate conditions.• Unique geographical or man-made features

can create a microclimate.

THE SEASONS Caused by Earth’s Tilt (23.50)

• As Earth travels around the sun, the north end of the axis points toward the sun during summer and away from the sun during winter.

• The seasons change as the amount of energy each hemisphere receives from the sun changes.