climate and climate change what causes climate? climate regions long-term changes in climate global...

Climate and Climate Change

What Causes Climate?

Climate Regions

Long-Term Changes in Climate

Global Changes in the Atmosphere

Table of Contents

Climate and Climate Change - What Causes Climate?

World Temperature Zones

Based on latitude, Earth’s surface can be divided into a tropical zone, two temperate zones, and two polar zones.


Ocean Currents

Ocean currents have a significant effect on marine climates around the world.


Rain Shadow

A mountain range can form a barrier to the movement of air masses and influence where precipitation falls.


Monsoons

In a summer monsoon, wind blows from the ocean onto land. In the winter, the monsoon reverses and blows from land to the ocean.


Light from the sun strikes Earth’s surface at different angles. An angle is made up of two lines that meet at a point. Angles are measured in degrees. A full circle has 360 degrees.When the sun is directly overhead near the equator, it is at an angle of 90º to Earth’s surface. A 90º angle is called a right angle. What percentage of a circle is it?

A 90º angle is 25% of a full circle.

Percentages

- What Causes Climate?


Percentages

Practice Problem

Earth’s axis is tilted at an angle of 23.5º. About what percentage of a right angle is this?

It is about 26.1 percent of a right angle.



The Seasons

The seasons are caused by the tilt of Earth’s axis as Earth travels around the sun.


Seasons Activity

Click the Active Art button to open a browser window and access Active Art about the seasons.



Building VocabularyAfter you read the section, reread the paragraphs that contain definitions of Key Terms. Use what you have learned to write a meaningful sentence using each Key Term.


Key Terms: Examples:

climate Climate refers to the average, year-after-year conditions of temperature, precipitation, winds, and clouds in an area.

microclimate A small area with climate conditions that differ from those around it may have its own microclimate.

tropical zone The tropical zone is the area near the equator, between about 23.5º north latitude and 23.5º south latitude.

polar zone These polar zones extend from about 66.5º to 90º north and 66.5º to 90º south latitudes.


temperate zone

marine climate

continental climate

windward

Between the tropical zones and the polar zones are the temperate zones.

North America, South America, and Europe have mild marine climates, with relatively mild winters and cool summers.

Continental climates have more extreme temperatures than marine climates.

Rain or snow falls on the windward side of the mountains, the side the wind hits.


leeward

monsoon

The land on the leeward side of the mountains—downwind—is in a rain shadow.

Sea and land breezes over a large region that change direction with the seasons are called monsoons.


End of Section:What Causes

Climate?

Climate and Climate Change - Climate Regions

Climate Graphs

A graph of average temperature (left) can be combined with a graph of average precipitation (middle) to form a climate graph. These graphs are for a tropical wet-and-dry region.


Climate Regions

Climate regions are classified according to a combination of temperature and precipitation. Climates in highland regions change rapidly as altitude changes.


Dry Climates

Dry climates include arid and semiarid climates. Albuquerque, New Mexico, has an arid climate.


Temperate Marine Climates

There are three types of temperate marine climates: marine west coast, humid subtropical, and Mediterranean. Eugene, Oregon, has a marine west coast climate.


Temperate Marine Climates

Santa Barbara, on the coast of southern California, has a Mediterranean climate. Mild temperatures throughout the year make the area ideal for growing olives and citrus fruits.


Temperate Continental ClimatesTemperate continental climates include humid continental and subarctic climates. Subarctic climates have cool summers and cold winters. Anchorage, Alaska, has a subarctic climate.


Polar Climates

Polar climates include ice cap and tundra climates. The tundra climate region stretches across northern Alaska, Canada, and Russia.


Comparing and ContrastingAs you read, compare and contrast the six main climate regions by completing a table like the one below.

Climate Region Precipitation Temperature

Tropical rainy Heavy precipitation Hot

Dry Little rainfall Hot or Cold

Temperate marineDry to rainy, depending on season and location

Cool to hot, depending on season and location

Temperate continental

Light to moderate rainfallCold to hot, depending on season and location

Polar Dry Cold

HighlandsWetter than nearby

lowlandsCooler than nearby

lowlands

- Climate Regions


Climate Regions

Click the Video button to watch a movie aboutclimate regions.

- Climate Regions


Links on Climates of the World

Click the SciLinks button for links on climates of the world.

- Climate Regions


End of Section:Climate Regions

Climate and Climate Change - Long-Term Changes in Climate

Ice Ages

The map shows the parts of North America that were covered by glaciers 18,000 years ago. On the steppe near the glaciers lived many mammals that are now extinct, including woolly mammoths.


Ice Ages and Temperature

The graph shows the estimated average worldwide temperature over the last 350,000 years. During this time, cold glacial periods (blue) alternated with warmer interglacial periods (pink).

- Long-Term Changes in Climate



Number of years ago, estimated average global temperature in degrees Celsius

Reading Graphs:

What does the x-axis of the graph represent? What does the y-axis represent?




Periodic ups and down in average global temperature; the temperature changes represent ice ages and warmer times in between. These changes may have been caused by changes in Earth’s position in space.

Interpreting Data:

What pattern do you see in these data? How would you explain this pattern?




The pattern probably will continue. Global temperatures are relatively high now, so they may decrease in the future, all else equal. Earth eventually will have another ice age.

Predicting:

Based on the pattern over the last 350,000 years, predict how global temperature will change in the future.


Climate and Climate Change - Long-Term Changes in Climate

Moving Continents

The continents have moved over millions of years. These movements have resulted in climate changes.


Continental Drift Activity

Click the Active Art button to open a browser window and access Active Art about continental drift.



Identifying Supporting EvidenceAs you read, identify the evidence that is used to show that climates change.

Hypothesis

Climate change

Evidence

Tree rings

Pollen

Evidence of past glaciers



End of Section:Long-Term Changes in

Climate

Climate and Climate Change - Global Changes in the Atmosphere

Greenhouse Effect

Sunlight enters a greenhouse and is absorbed. The interior of the greenhouse radiates back energy in the form of infrared radiation, or heat. Much of the heat is trapped and held inside the greenhouse, warming it.


Global Warming

Scientists think that an increase in carbon dioxide in the air is a major factor in global warming.


The Ozone Hole

Chemicals produced by humans have damaged the ozone layer. A large are of reduced ozone, or ozone hole, has been created over Antarctica.


Asking QuestionsBefore you read, preview the red headings. Ask a what or how question for each heading. As you read, write answers to your questions.

What is the greenhouse effect?

The process by which gases in Earth’s atmosphere trap solar energy

Why is ozone depletion a concern?

A decrease in ozone in the stratosphere causes more ultraviolet light, which is harmful, to reach Earth’s surface.

Questions Answers

- Global Changes in the Atmosphere


The Greenhouse Effect

Click the Video button to watch a movie aboutthe greenhouse effect.



More on the Greenhouse Effect

Click the Planet Diary button for an activity aboutthe greenhouse effect.



End of Section:Global Changes

in the Atmosphere


Graphic Organizer

Climate

is affected by

is determined by

Temperature Precipitation

is affected by

Latitude AltitudePrevailing

winds

Distance from water

Ocean currents

Mountain ranges


End of Section:Graphic Organizer

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