1. Introduction
Weather is the condition of the atmosphere in one place during a short period of time. 
Climate is the term for weather patterns that an area typically experiences during a long period of time. 
Both weather and climate are influenced by… 
direct sunlight. 
ocean currents. 
winds. 
the features of the earth’s surface.
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2. The Greenhouse Effect
A small amount of the sun’s radiation reaches the earth’s atmosphere; however, enough remains to warm the earth’s land and water. 
The earth’s atmosphere keeps heat from escaping back into space too quickly, creating a greenhouse effect, which traps the sun’s warmth for growing plants. 
Without this greenhouse effect, the earth would be too cold for most living things.
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3. Earth’s Tilt and Rotation
The earth has an axis–an imaginary line that runs through its center between the North Pole and the South Pole. 
Because the Earth’s axis is tilted at a 23½° angle, not all places on earth receive the same amount of direct sunlight. 
The earth’s tilt affects the temperature– a measure of how hot or cold something is–of places.
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4. Earth’s Tilt and Rotation (cont.)
The earth rotates, or spins, on its axis from west to east, making one complete rotation every 24 hours, and causing day and night.
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5. Earth’s Revolution
While rotating on its axis, the earth also travels in an orbit, or path, around the sun. 
The earth’s revolution, or trip around the sun, takes 1 year, or 365¼ days, which results in the changing of seasons and the amount of daylight. 
March 21 and September 23 are called equinoxes because the sun is directly over the equator and the days and nights are equal in length, marking the beginning of spring or fall.
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6. Earth’s Revolution (cont.)
June 21 and December 22 are called solstices because the sun is directly over the Tropic of Cancer or the Tropic of Capricorn, marking the beginning of summer or winter. 
The amount of sunlight at the poles varies most dramatically as the earth’s revolution and tilt cause the changing seasons. 
For six months one Pole is slanted toward the sun, receiving continuous sunlight, while the other Pole is slanted away from the sun, receiving no sunlight.
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7. Chart Supplement 1.1

8. Click the mouse button or press the Space Bar to display the answer.
What latitude is the Tropic of Cancer? Tropic of Capricorn?
The Tropic of Cancer is 23° N.
The Tropic of Capricorn is 23° S.
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9. Click the mouse button or press the Space Bar to display the answer.
Why does March 21 generally mark the beginning of spring in the Northern Hemisphere?
The sun is directly over the Equator.
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10. End of Section 1

11. Section 2

12. Introduction
The climate of a location depends in part on latitude, elevation, wind and ocean currents, and landforms.
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13. PLACE
Latitude
Bands of latitude can be used to generally describe the climate in certain climate zones. 
The zones indicate how the sun’s rays strike places within the zones. 
During the earth’s yearly revolution around the sun, the sun’s direct rays fall on the earth in a regular pattern.
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14. Low Latitudes
The latitudes between the Tropic of Cancer and the Tropic of Capricorn are known as the low latitudes. 
The low latitudes receive direct rays of the sun year-round, have a very warm to very hot climate, and are often said to be in the tropics.
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15. Polar Areas
When either the Northern Hemisphere or the Southern Hemisphere is tilted toward the sun, its polar area receives continuous sunlight. 
Starting on about June 21, the sun never sets above a line called the Arctic Circle (66½° N). 
In the Southern Hemisphere, the Antarctic Circle (66½° S) is a line that marks the boundary of endless daylight starting on about December 22.
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16. High and Middle Latitudes
The latitudes between the North Pole and the Arctic Circle and between the South Pole and the Antarctic Circle are known as the high latitudes. 
The high latitudes receive slanted rays of the sun throughout the year and have a generally cold climate. 
The latitudes between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere and between the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere are known as the middle latitudes.
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17. High and Middle Latitudes (cont.)
Many places in the middle latitudes have a temperate climate–one that ranges from fairly hot to fairly cold. 
The weather of most places in the middle latitudes changes dramatically with the seasons.
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18. Elevation The temperature of a place depends on its elevation. 
The earth’s atmosphere gets thinner as altitude increases, so air temperatures decrease with elevation. 
For every 1,000 feet gained, the temperature drops about 3.5°F. 
High mountains are generally cold places covered with ice and snow year-round, even though sunlight is very bright.
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19. Wind and Ocean Currents
MOVEMENT
Wind and Ocean Currents
Wind and water combine with the effects of the sun to create the weather and climates of the earth. 
Wind is air moving across the surface of the earth and occurs when temperatures create differences in air pressure.
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20. Wind Patterns
Prevailing winds are winds that blow in fairly constant patterns and are divided into belts of latitude. 
Trade winds are the prevailing winds in the low latitudes, blowing toward the Equator from about 30° N latitude and 30° S latitude. 
Westerlies are the prevailing winds in the belts between 30° N and 60° N latitude and between 30° S and 60° S latitude.
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21. Wind Patterns (cont.)
Easterlies lie between 60° N latitude and the North Pole and between 60° S latitude and the South Pole. 
Easterlies blow somewhat from east to west and push cold polar air toward the middle latitudes. 
The doldrums is a frequently windless area at the Equator.
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22. Map Supplement 2.1

23. Ocean Currents
Ocean currents, cold and warm “rivers” of seawater, generally move clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. 
Currents are caused by... 
the rotation of the earth. 
moving air. 
differences in the ocean’s water temperature.
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24. Ocean Currents (cont.)
Ocean currents affect the climates of coastal lands that they flow along. 
Water and winds interact with temperature to cause precipitation– the falling of moisture to the earth in the form of rain, sleet, hail, or snow.
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26. Landforms The earth’s surface features can also affect climates. 
PLACE
Landforms
The earth’s surface features can also affect climates. 
Temperatures of land areas located near oceans do not change as much as temperatures of interior land areas. 
Interior land areas experience much hotter summers and much colder winters than land areas near the ocean.
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27. PLACE
Landforms (cont.)
Temperatures, precipitation, and surface features interact with wind to affect climate. 
Winds that blow over an ocean and then meet a mountain range on the windward side–the side facing the direction from which the wind is blowing–are pushed upward. 
The air that descends the other side of the mountains, the leeward side, is dry and becomes warmer as it falls, resulting in a dry area called a rain shadow.
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29. Click the mouse button or press the Space Bar to display the answer.
What and where are the trade winds, westerlies, and polar easterlies?
Trade winds blow in the low latitudes. Westerlies blow west to east in the middle latitudes. Polar easterlies blow east to west from the poles.
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30. Click the mouse button or press the Space Bar to display the answer.
What factors affect climate in your region?
Latitude, elevation, and currents affect climate.
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31. End of Section 2

32. Section 3

33. Introduction
Climate affects the soil and natural vegetation–the plant life that grows in an area if people have not changed the natural environment. 
Geographers often divide the earth into five major climate regions: 
tropical 
dry 
mid-latitude 
high latitude 
highland
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35. REGION
Tropical Climates
Tropical climate regions are found in or near the low latitudes. 
The two kinds of tropical climate regions are tropical rain forest and tropical savanna.
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36. Tropical Rain Forest Climate
Tropical rain forest climate regions are hot and wet throughout the year and are found near the Equator. 
Tropical rain forest vegetation grows thick in layers formed at different heights. 
The Amazon River basin in South America contains the world’s largest tropical rain forest. 
The same climate is found in other parts of South America, in the Caribbean area, and in parts of Africa and Asia.
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37. Tropical Savanna Climate
Tropical savanna climate regions have a dry season in winter and a wet season in summer. 
Savannas are located farther from the Equator than tropical rain forest regions. 
Savannas are characterized by high temperatures, clumps of coarse grass, and few trees.
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38. REGION
Dry Climates
Because of vegetation, dry climate regions are also divided into two types–desert and steppe.
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39. Desert Climate Deserts are areas with sparse plant life. 
Scattered vegetation such as scrubs and cacti can survive with little rain. 
Underground springs, however, may support an oasis, an area of lush vegetation. 
Deserts can be extremely hot during the day and cold at night. 
Desert climates cover about one-fifth of the earth’s land surface.
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40. Steppe Climate
Dry areas, often bordering deserts, are called steppes. 
Steppe vegetation consists of bushes and patches of short grasses without many trees. 
The largest steppe stretches across eastern Europe and western and central Asia.
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41. Mid-latitude Climates
REGION
Mid-latitude Climates
The world has four mid-latitude climate regions: 
marine west coast 
Mediterranean 
humid subtropical 
humid continental
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42. Marine West Coast Climate
Marine west coast climate regions are found along western coastlines between latitudes 30° and 60° north and south. 
Ocean winds produce cool summers and mild but damp winters. 
Rainfall is quite heavy in places, and it supports both evergreen and deciduous trees. 
Most deciduous trees lose their leaves in autumn and have broad leaves. 
Mixed forests are those with both evergreen and deciduous trees.
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43. Mediterranean Climate
Areas that have weather patterns and vegetation like those near the Mediterranean Sea are called Mediterranean climate regions. 
These regions are generally found in coastal lands between latitudes 30° and 40° north and south.
They have mild rainy winters and hot, sunny summers. 
Vegetation in Mediterranean climate regions is called chaparral, which includes woody bushes and short trees that grow in dense forests.
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44. Humid Subtropical Climate
Humid subtropical climate regions have a pattern of wind and high pressure related to nearby oceans, which causes high humidity. 
Rain falls throughout the year with heavy summer thunderstorms, while winters are generally short and mild. 
Vegetation in humid subtropical climate regions includes grasslands, or prairie lands, and forests. 
Forests consist of a mixture of broad-leaved evergreen trees, deciduous trees, and needle-leaved evergreens.
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45. Humid Continental Climate
Humid continental climates are more influenced by landmasses than by winds, precipitation, or ocean temperatures. 
The farther north in the humid continental climate regions, the longer and more severe are the snowy winters and the shorter and cooler the summers.
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46. High Latitude Climates
REGION
High Latitude Climates
There are three types of high latitude climates: 
subarctic 
tundra 
ice cap 
The subarctic climate regions lie just south of the Arctic Circle. 
In some places only a thin layer of surface soil thaws. The frozen subsoil is known as permafrost.
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47. Subarctic Climate
The subarctic’s severe conditions limit the variety of plant life to mainly needle-leaved evergreen trees. 
One vast subarctic forest stretches across northern Russia. 
Geographers often use taiga, the Russian word for this forest, to refer to subarctic climate regions in general.
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48. Tundra Climate
The tundra climate regions have bitterly cold winters with greatly reduced sunlight. 
In summer the sun’s slanted rays bring constant light but little heat. 
The tundra region’s thin soil above the permafrost supports only certain low plants and lichens–plants that grow on rocks.
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49. Ice Cap Climate
Because monthly temperatures average below freezing, ice cap climate regions support no vegetation, except a few species that can live on rocks.
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50. REGION
Highland Climates
In mountain areas the climate varies with elevation. The higher the altitude, the cooler the air. 
Near the bases of mountains, deciduous and evergreen forests grow. 
Higher up are meadows with small trees and shrubs. 
Above the timberline, the elevation above which it is too cold for trees to grow, are scattered tundra plants.
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52. HUMAN/ENVIRONMENT INTERACTION
Climatic Changes
Climates change gradually over time. During the last 1 to 2 million years, for example, the earth passed through four eras where large areas were covered with glaciers. 
Geographers have developed several possible explanations for what caused glacial eras. 
One explanation is that variations in the sun’s output of energy and in the earth’s orbit may have caused our world to absorb less solar energy and cool off.
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53. Climatic Changes (cont.)
HUMAN/ENVIRONMENT INTERACTION
Climatic Changes (cont.)
Another hypothesis, or scientific explanation, suggests volcanic activity over long periods of time released massive amounts of dust into the atmosphere, which might have had a cooling effect. 
Geographers also believe that human activities today cause changes in the world’s climates. For example: 
Smoke from the burning of fossil fuels scatters the sun’s rays.
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54. Climatic Changes (cont.)
HUMAN/ENVIRONMENT INTERACTION
Climatic Changes (cont.)
The burning of fossil fuels releases carbon dioxide, preventing some surface heat from leaving the atmosphere. 
Gases produced by burning fuels mix with water in the air, forming damaging acids that fall in rain and snow. 
The exhaust from automobiles helps create smog, a haze caused by the sun’s ultraviolet radiation that endangers people’s health. 
Water projects, such as dams and river diversions, may cause new areas to become dry.
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55. HUMAN/ENVIRONMENT INTERACTION
El Niño
El Niño is a recurring climatic phenomenon that has an important impact on global weather by setting off changes in the atmosphere. 
A weakening of trade winds that blow east to west, allowing a large mass of warm water to move east toward South America, characterizes El Niño. 
El Niño used to occur every four to five years but now happens more often.
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56. HUMAN/ENVIRONMENT INTERACTION
El Niño (cont.)
Scientists are not certain what causes El Niño, but many link it with global warming. 
Experts believe that El Niño distributes the extra energy produced by global warming.
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57. Click the mouse button or press the Space Bar to display the answer.
What and where are the five main climate regions?
Tropical: low latitudes
Dry: one-fifth of the earth’s land surface
Mid-latitude: middle latitudes
High-latitude: high latitudes
Highland: varies
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58. Click the mouse button or press the Space Bar to display the answer.
In what ways may the earth’s climate change due to human and natural processes?
Changes include less sunlight, lower temperatures, a greenhouse effect, acid rain, and more dry areas.
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59. End of Section 3

60. Click the mouse button or press the Space Bar to display the answers.
What unit on this map measures scale?
inches
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What is the scale of distance?
1 inch= 250 miles
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61. Click the mouse button or press the Space Bar to display the answers.
What unit on this map measures scale?
inches
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What is the scale of distance?
1 inch= 5 miles
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62. Click the mouse button or press the Space Bar to display the answer.
How far is it from Orlando to Atlanta?
about 450 miles
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63. Click the mouse button or press the Space Bar to display the answer.
Suppose you are traveling through West Palm Beach on I-95. About how far is it from the intersection of Route 702 to the intersection of Route 98?
about 12 miles
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