This document provides information about factors that affect climate and how scientists study past climates. It discusses how latitude, altitude, distance from large bodies of water, ocean currents, prevailing winds, mountains, and seasonal winds influence temperature and precipitation patterns. Scientists can learn about ancient climates by examining pollen, tree rings, and ice cores to see what plants lived in different areas over time and identify patterns that indicate climate conditions. Natural factors that can cause climate change include variations in Earth's orbit, solar activity, volcanic eruptions, and ocean currents.

1. Climate
Unit 8 - 6th Grade Science
Unit 3 - 6th Grade Advanced Science

2. Lesson 1: What causes climate?
• What factors affect temperature?
• 6.E.2B.3
• 6.E.2B.4
• What factors affect precipitation?
• 6.E.2B.3
• 6.E.2B.4

3. What factors affect temperature?
• Temperature is affected by latitude, altitude, distance from large
bodies of water, and ocean currents.
• Temperature changes cause evaporation and precipitation. The water
cycle determines climate patterns.
Page 105

4. Latitude
• Based on latitude, Earth’s surface can be divided into three types of
temerpature zones.
• Tropical zone – between 23.5 north and 23.5 south latitudes. Warm
climate, receives nearly direct sunlight all year
• Polar zones – between 66.5 and 90 north and 66.5 and 90 south latitudes.
Cold climate, receives sunlight at a low angle.
• Temperate zones – between 23.5 and 66.5 north and between 23.5 and
66.5 south latitudes. Warm or hot summers and cool or cold winters.
• Color in the picture in figure 2.
• Page 106

5. Altitude
• In the troposphere, temperatures decreases about 6.5 degrees
Celsius for every 1 km increase in altitude.
• Mountainous areas have cooler climates than the lower areas around
them.
• Page 107

6. Calculate temperature change
• If it was 30 degrees C at the base of Mount Chimborazo, about how
cold would it be at the peak?
• Remember, temperature decreases 6.5 degrees C for every 1 Km in
altitude.
• Mount Chimborazo is 6309 meters high.

7. Distance from large bodies of water
• Oceans moderate the temperature of nearby land.
• Water heats up 5 times more slowly than land. It cools down slower
too.
• Winds off the oceans prevent extremes of hot or cold in coastal
regions.
• Marine climates – mild winters and cool summers
• Continental climates – hot summers and cold winters
• Page 108

8. Apply it p. 108
1. Where are Juneau and Fairbanks located in relation to each other?
2. Which climate data do you think describe Juneau, A or B? Which
describe Fairbanks, A or B? Why?
3. Which city on the map do you think represents the set of data for
City C? Why?

9. Ocean currents
• Marine climates are influenced by ocean currents (streams of water within
the oceans that move in regular patterns).
• Global winds drive surface currents.
• Deep currents form as cold, salty water becomes more dense, sinks, and
flows along the ocean floor.
• Atlantic Gulf Stream – warm current
• California current – cold current
• Page 109

10. What factors affect precipitation?
• The main factors that affect precipitation are prevailing winds,
presence of mountains, and seasonal winds.
• Page 110

11. Prevailing winds
• These winds move air masses from place to place.
• The amount of water vapor in the air masses influences how much
rain or snow might fall.
• The amount of water vapor in prevailing winds depends on where the
wind blows from.
• Page 110

12. Mountain Ranges
• When humid winds blow from the ocean toward coastal mountains,
they are forced to rise.
• Rising air cools and its water vapor condenses forming clouds.
• Rain or snow falls on the windward side of the mountain.
• Land on the leeward side of the mountain is in a rain shadow and
receives very little rain during the year.
• Page 110

13. Rain Shadow activity p. 110
1. Fill in the boxes to describe what happens as prevailing winds meet
mountains.
2. Shade in the landscape to show what the vegetation might look like
on both sides of the mountain.

14. Seasonal winds
• Sea and land breezes over a large region that change direction with
the seasons are called monsoons.
• The air blowing from over the ocean is warm and humid. As the
humid air rises over the land, it cools and its water vapor condenses
into clouds that produce heavy rainfall.
• Complete Assess Your Understanding
• Page 111

15. Assess Your Understanding p. 111
2a. What is the leeward side of a mountain?
2b. How do prevailing winds affect precipitation?

16. Lesson 2: Climate regions
• How do scientists classify climates?
• 6.E.2B.3
• 6.E.2B.4
• What are the six main climate regions?
• 6.E.2B.3
• 6.E.2B.4
Page 112

17. How do scientists classify climates?
• Scientists classify climates according to two major factors:
temperature and precipitation.
• Scientists use a system developed around 1900 by Wladimir Koppen.
• Aside from temperature and precipitation, Koppen also looked at
distinct vegetation in different areas.
• Page 113

18. What are the six main climate regions?
• The six main climate regions are tropical rainy, dry, temperate marine,
temperate continental, polar, and highlands.
• Page 114

19. Tropical rainy climates
• The tropics are an area that have two types of rainy climates: tropical wet
and tropical wet-and-dry.
• Tropical wet – Many rainy days and frequent afternoon thunderstorms.
(Rain forests)
• Tropical wet-and-dry – Receives slightly less rain than tropical wet areas.
Tropical wet-and-dry areas have distinct rainy and dry seasons. (Savannas)
• Page 116

20. Dry climates
• A climate is dry if the amount of precipitation that falls is less than the
amount of water that could potentially evaporate.
• Dry climates include semiarid and arid climates.
• Semiarid areas – located on the edges of deserts and called steppes.
• Arid areas – these are deserts. They can be hot or cold, rocky or sandy.
(<25 cm of rain per year)
• Page 117

21. Temperate marine climates
• There are found along the coasts of continents in the temperate zones.
• There are three kinds of temperate marine climates: humid subtropical,
marine west coast, and Mediterranean.
• Humid subtropical – wet and warm, but not as constantly hot as the
tropics.
• Marine west coast – Found on the west coasts of continents above 40
north and 40 south latitudes. Winters are mild and rainy. Summer
precipitation varies.
• Mediterranean – This climate is mild with two seasons: Summers are warm
and dry, winters are cool and rainy.
• Page 118

22. Temperate continental climates
• Temperate continental climates are only found on continents in the
Northern Hemisphere, and include humid continental and subarctic.
• In the Southern Hemisphere, there are no large land areas at the right
latitude for this climate to occur.
• Page 119

23. Temperate continental climates
• Humid continental – shifting tropical and polar air masses bring
constantly changing weather. Winters are bitterly cold. Summers are
hot and humid.
• Subarctic – Lie north of the humid continental climates. Short and
cool summers. Long and bitterly cold winters.
• Page 119

24. Polar climates
• The polar climate is the coldest climate region and includes the tundra and
the ice cap climates.
• Tundra – Stretches across northern Alaska, Canada, and Russia. Cool
summers and bitterly cold winters. Tundra has permanently frozen soil
called permafrost.
• Ice Cap – Average temperatures are always at or below freezing. The land is
covered with ice and snow. Dry air. Lichens and few small plants grown on
the rocks.
• Page 120

25. Highlands
• Temperature falls as altitude increases, so highland regions are colder
than the regions that surround them. (Land on mountains)
• Complete the Apply It activity on page 121 by completing the bar
graph.
• Page 120

26. Lesson 3: Changes in Climate
• How do scientists study ancient climates?
• 6.E.2B.4
• What natural factors can cause climate change?
• 6.E.2B.4
• Page 122

27. Otzi the Ice Man p. 122
Have you ever seen somethiing so bizarre that you stopped right in
your tracks? That’s just what happened to a pair of hikers in 1991.
During a hike in the Alps, they came across something strange. It was a
5000 year old mummified body of a man emerging from a melting
glacier.
Archaeologists names the mummy Otzi. After removing him from the
ice, they began to study his weapons, clothes, and tools. What they
found surprised them. There was evidence that early humans knew
how to make warm, waterproof clothing. Otzi’s shoes were very
complex. They had bearskin soles, top panels made of deerhide, and
netting made of tree bark to give them traction on snow. Soft grass
inside the shoes acted like a warm sock.

28. Otzi the Ice Man p. 122
• What do you know about climate changes in the past?
• How do you think climate changes might have affected plants and
animals?

29. How do scientists study ancient climates?
• In studying ancient climates, scientists follow an important principle: If plants or
animals today need certain conditions to live, then similar plants and animals in
the past also required those conditions.
• What evidence have scientists found about climate change in Greenland?
Fossils of magnolias and palm trees
• What must scientists consider in order to make a hypothesis about the ancient
climate of Greenland?
They must consider the climatic conditions that magnolias and palm trees
required today.
• Page 123

30. Evidence of Climate Change
• Pollen
• Tree rings
• Ice cores

31. Pollen
• Each type of plant has a particular type of pollen.
• Scientists can drill down into these layers [mud] and bring up samples
to examine.
• Using a microscope, scientists can tell what types of plants lived
there.
• Page 124

32. Tree rings
• Tree rings also tell a story about ancient climates.
• Trees grow a new ring each summer.
• Wide rings indicate a good growing season that was long and wet.
• Narrow rings indicate a dry year or a short growing season.
• Page 124

33. Ice cores
• Ice cores have a layer for each year, just like tree rings.
• Scientists can analyze what’s in the layers of ice, such as pollen and
dust.
• Page 124

34. Inquiry
• Where in a lake bottom would the oldest layers of sediment be found?
• At the deepest part
• How could pollen from sediment layers provide information about past
climates?
• Scientists can learn what plants lived in the area during different periods of
time.
• How could tree rings record climate changes?
• Rings progress from oldest to newest starting at the center. Thin rings
indicate cool, dry conditions. Wide rings indicate warm, wet conditions.

35. What natural factors can cause climate
change?
• Possible explanations for major climate changes include movement of
continents, variations in the position of Earth relative to the sun,
major volcanic eruptions, and changes in the sun’s energy output.
• What do these explanations have in common?
• All four causes are natural and not caused by humans.
• What makes volcanic eruptions different from the other four causes?
• Volcanic eruptions occur more frequently than the other causes.
• Page 125

36. Movement of continents
• The continents have not always been located where they are now.
• About 200 million years ago, most of the land on Earth was part of a
single continent called Pangaea.
• The movement of continents over time changed the locations of land
and sea. These changes affected the global patterns of winds and
ocean currents, which slowly changed climates.
• Page 125

37. Figure 3 p. 125
• How do you think the movement of continents over 200 million years
affected India’s climate?
• India became warmer because it moved closer to the equator.
• How do you think it affected North America’s climate?
• It made North America’s climate cooler because it moved north.
• Which continents probably had the most drastic climate changes due to
movement of the continents?
• North America and Africa

38. Earth’s position and ice ages
• The angle of Earth’s axis and the shape of Earth’s orbit affect Earth’s
climate.
• Earth orbits the sun in an elliptical orbit.
• When Earth’s orbit is more elliptical, less sunlight reaches the earth during
the year causing an ice age.
• What has caused ice ages to occur on Earth?
• When Earth’s orbit around the sun grows more elliptical every 100,000
years, less sunlight reaches the planet.
• Page 126

39. Earth’s position and ice ages
• During each ice age, huge sheets of ice called continental glaciers covered
large parts of Earth’s surface.
• Glaciers carved grooves in solid rock and deposited piles of sediment.
• Scientists have concluded that there were about 20 major ice ages over the
last 2 million years.
• What has affected the severity of ice ages?
• Changes in the angle at which Earth’s axis tilts, and changes in the direction
of the axis.
• Page 126

40. Volcanic Activity
• Major volcanic eruptions release huge quantities of ash and aerosols
into the atmosphere.
• Scientists think that aerosols and ash reflect away some of the
incoming solar radiation, and may lower temperatures.
• Page 127

41. Solar energy
• Short term changes in climate have been linked to changes in the
amount of light given off by the sun.
• Repeats on a regular 11 year cycle
• Little Ice Age 1600 – 1850
• Sunspots increase when the sun gives off more light.
• Page 127

42. Assess Your Understanding p. 127
1a. What principle do scientists follow when studying ancient climates?
• Living things today need the same conditions to live as simiar living
things did in the past.
1b. How does a volcanic eruption affect climate?
Ash and aerosols reflect radiation and lower temperatures.

43. Lesson 4: Human Activities and Climate
Change
• How are human activities affecting earth’s climate?
• 6.E.2A.2
• 6.E.2B.4

44. How Big is Your Footprint? p.128
Today people are measuring their effect on the environment by looking
at their carbon footprint. Carbon is found in two of the greenhouse
gases most responsible for warming Earth’s climate.
Your carbon footprint measures the total amount of greenhouse gases
you emit directly and indirectly. Cars, factories, and home heating all
rely on fuels that release carbon into the atmosphere.
The manufacturing of products you use, like food and clothing, does
too. When people know how big their carbon footprints are, they can
make changes that improve their own lives and the environment.

45. Inquiry
• Which methods of transportation release more carbon into the air,
and which methods release less?
Most – motor vehicles, airplanes, trains, boats, etc.
Least – walking, bicycling, etc.
• How would riding on a bus or train instead of riding in a car reduce
your carbon footprint?
More people can be transported at once and so the carbon footprint
per person is smaller.

46. Greenhouse effect
• The atmosphere keeps the earth’s surface warm through a process
called the greenhouse effect.
• Greenhouse gases such as water vapor, carbon dioxide, and methane
absorb heat leaving the surface of the earth, then radiate some heat
back toward earth.
• Greenhouse gases make up less than 1% of the atmosphere.
• Which gases trap the most heat?
• Carbon dioxide, methane, and water vapor
• Page 129

47. Levels of greenhouse gases
• Human activities are increasing the level of greenhouse gases in the
atmosphere and producing changes in climate worldwide. This increase is
causing global temperature to rise.
• Global warming is the gradual increase in temperature of Earth’s
atmosphere.
• What is causing levels of greenhouse gases in the atmosphere to increase?
• Burning fossil fuels to power cars, generate electricity, heat homes,
manufacture goods, and raise livestock.
• Page 130

48. Figure 2 p. 130
• How did the level of carbon dioxide change from the year 1000 to
1800?
• Small fluctuations, but mainly stayed the same.
• What happened after 1800?
• The carbon dioxide level increased dramatically
• Why do you think carbon dioxide levels started to increase around
1800?
• Industrial Revolution

49. Effects of global warming
• The effects of global warming include melting glaciers, rising sea
levels, drought, desertification, changes to the biosphere, and
regional changes in temperature.
• What have global temperatures been like over the past 800,000
years?
• Global temperatures have gone up and down.
• How do scientists predict the possible effects of global warming?
• They analyze past events.
• Page 131

50. Figure 3 p. 131
• What are some cities vulnerable to rising sea levels?
• Charleston
• Beaufort
• New Orleans
• Wasington, DC.
• Any coastal city at or below sea level today.

51. Limiting global warming
• Solutions for limiting global warming and climate change include
finding clean, renewable sources of energy, being more energy
efficient, and removing carbon from fossil fuel emissions.
• What is a clean energy source?
• An energy source that releases very small amounts of greenhouse
gases.
• What are examples of clean energy sources?
• Solar, wind, geothermal, nuclear, and tidal energy
• Page 132

52. Assess Your Understanding p. 133
• What is a greenhouse gas?
• A gas that traps infrared energy leaving Earth’s surface.
• What are some solutions for reducing greenhouse gases?
• Use clean energy, carbon capture technology
• What are ways that individuals can become more energy-efficient?
• Turn off lights in unused rooms, use public transportation, ride
bicycles or walk instead of using motor vehicles.