1. Climates of the Earth
Chapter 3

2. Section 1: Earth-Sun Relationships
There is an important difference between climate and weather
Weather is the condition of the atmosphere in one place over a short period of time, such as hours or days
Climate refers to the average weather conditions as measure over many years
Climate is reason why you decide to buy certain types of clothing to wear based on where you live

3. Earth’s Tilt and Rotation
Relationship between earth and sun directly affect climate
Important aspect is the Earth’s axis, is tilted
Axis runs through center of planet
Currently, Earth is tilted at 23.5 degrees
Because of this, not all places on Earth receive direct sunlight at same time
Tilt affects the temperature of a particular place

4. Temperature Measure of how hot or cold a place is
Measured in degrees Fahrenheit or Celsius
Earth rotates on its axis, making one complete rotation every 24 hours
Every side of the world receives sunlight (gives us day and night)
Side not facing the sun is colder- our nights are colder than days

5. Earth’s Revolution
Takes Earth approximately 365 days to complete one revolution around the sun
Earth’s revolution, combined with tilted axis, affects the amount of sunlight that reaches different locations on Earth at different times of year
People who live in Northern Hem. Experience summer when northern hem. Is titled toward the sun
Seasons are reversed north and south of the Equator

6. Equal Night Twice a year, the direct sunlight falls on the Equator
This day is called an equinox, meaning “equal night”, because daytime and nighttime hours are equal
Two equinoxes mark the shift in seasons between winter and spring and between summer and fall

7. Solstice
The longest day of sunlight in the Northern Hemisphere occurs when sunlight strikes the Tropic of Cancer “23.5 degrees N” directly
Happens around june 21
Known as the summer solstice and marks the beginning of summer in Northern Hem.
When sun directly hits 23.4 degrees S, we get the shortest day of sunlight known as winter solstice (beginning of winter)- the equinoxes come in between the two solstices

8. Sunlight near the Poles
For six months a year, one pole gets continuous sunlight, while the other pole receives none
Continuous daylight, known as midnight sun, is caused by the tilt of the Earth as it revolves around sun
Parts of Alaska have become tourist destinations because of the Midnight Sun

9. The Greenhouse Effect
Even on warmest days, only some of sun’s rays pass through Earth’s atmosphere
Some is reflected back into space
Atmospheric gases absorb radiate heat energy and trap it so it cannot escape back into space
Greenhouse effect is the warming of the earth that occurs when sun’s radiation passes through atmosphere, is absorbed by the earth, and is radiated as heat energy back into the atmosphere where it cannot escape
Without it, average temperature on Earth would be 0 degrees F

10. Questions
What is the relationship between weather, climate, axis, temperature, and revolution?
How is temperature affected by the tilt of the earth?
What is the greenhouse effect?
What is the difference between equinoxes and solstices?

11. Section 2: Factors Affecting Climate
It matters because the climate of a particular place may have extreme weather and temperature ranges caused by several geographic features
Latitude and elevation, along with wind and ocean currents influence its climate

12. Latitude, Climate, and Elevation
The low latitude zone is between 30 S and 30 N
Includes Tropic of Capricorn, Tropic of Cancer, and Equator
Receives direct rays from sun all year and therefore has warm to hot climates
High latitude zone includes polar areas from 60 N to 90 N and 60 S to 90 N
When either the Northern or Southern Hemisphere is tilted toward the sun, it receives nearly continuous sunlight
Midlatitudes are home to the most variable weather on Earth
Generally have a temperate climate, with dramatic seasonal weather changes

13. Elevation
At all latitudes, elevation influences climate because of the relationship between the elevation of a place and its temperature
Earth’s atmosphere thins as altitude increases
Thinner air is less dense and retains less heat
Thinner atmosphere filters fewer rays of the sun so they are brighter

14. Winds and Ocean Currents
Air moving across the surface of the Earth is called wind
Winds occur because sunlight heats the Earth’s atmosphere and surface unevenly
Warm temps cause air to rise and create areas of low pressure
Cool temps cause air to sink, which creates areas of high pressure
Cool air then flows in to replace warm rising air
Movements over the Earth’s surface cause winds to distribute sun’s energy around planet—wind patterns are crucial to a region’s climate

15. Ocean Currents
Ocean currents also help distribute energy around the planet
Cold water from polar areas moves slowly toward Equator
These are cold ocean currents because they consist of cooler water flowing into warmer water
Opposite is also true

16. Patterns of Wind and Ocean Currents
As wind blows because of temperature differences on Earth’s surface, warm air moves toward Poles and cool polar air towards equator
This movement of air creates the global winds that blow in constant patterns called prevailing winds
Because of the spin of the Earth, the winds blow diagonally rather than along strict directions

17. Winds
Generally named for the direction from which they blow, but they sometimes get names from early days of sailing
Prevailing winds of the lower latitudes are called trade winds- blow from NE toward equator in N Hemis and SE toward Equator in S Hemis.
westerlies are prevaling winds in midlatitudes- blow diagonally from West to East
Polar easterlies blow diagonally east to west in the high latitudes

18. Doldrums
Near equator, the horizontal movement of trade winds subsides as warm air rises
Leaves a narrow, generally windless band called the doldrums
Would hurt sailors in the past
Would have no wind to move them in the hottest parts of the Earth

19. Ocean Current Patterns
Ocean currents are caused by man of the same factors that cause winds, including Earth’s rotation, changes in air pressure, and differences in water temp.
Cold ocean currents cool lands they pass, while warm ocean currents bring warmer temps.

20. Influences on Weather Wind and water work together to affect weather
Driven by temperature, condensation creates precipitation, or water falling to the Earth
On a hot day, water vapor forms in the atmosphere from evaporated surface water
High temperature causes air to rise—as it rises it cools and results in condensation of water vapor into liquid, forming clouds
Further cooling causes rain to fall

21. Events that Alter Weather
El Nino- periodic change in the pattern of ocean currents, water temperatures, and weather in Mid-Pacific region
In an El Nino year, the normally low atmospheric pressure over western Pacific is replaced by higher pressure
Causes trade winds to diminish or even reverse
This reverses the ocean currents, drawing warm water from the west to the east

22. Effects of El Nino Influence climates around the world
Precipitation increases along the coasts of North and South America, making winters warmer and increasing the risk of floods
In SE Asia and Australia, drought and occasional forest fires occur
Climates in the midlatitudes are affected as well
Winter rains are heavier along the west coast of the US during El Nino years

23. Landforms and Climate
Large bodies of water are slower to heat and cool, so they tend to keep temps in surrounding lands moderate
Coastal lands receive the benefit of this influence and experience less changeable weather
Conversely, the interiors of the continents tend to experience extremes in seasonal temps.

24. Mountain Ranges Mountain ranges push wind upward
As a result, the rising air cools and releases moisture in the form of precipitation
Most of precipitation falls on the windward side of the mountain, or the side facing the wind
After precipitation is released, winds become warmer and drier as they descend on the opposite, or leeward, side of the mountains
Hot, dry air produces little precipitation in an effect known as a rain shadow
Often causes dry areas—and even deserts—to develop on leeward side of mountains

25. Questions
Which factors have the strongest affect on climate where you live?
How are climate patterns related to each zone of latitude?
How do wind currents and ocean currents affect climate?
How can landforms and bodies of water affect climate?

26. Section 3: World Climate Patterns
It matters because….
Climate patterns vary from region to region
Factors such as wind and air pressure can create zones where a climate becomes quite dramatic

27. Climate Regions and Biomes
Climates in the world are organized into 4 climate zones: tropical, dry, midlatitude, and high-latitude
Climates support different kinds of biomes
Biome is a major type of ecological community defined primarily by distinctive natural vegetation and animal groups
Characteristics may overlap with other biomes

28. Tropical Climates
Found near low latitude in areas otherwise referred to as the tropics—have wet and dry climates
Tropical rain forest climates have an average daily temperature of 80 F, and since the warm air is humid, it rains almost daily
Annual rainfall is from inches
Strips the soil of nutrients

29. Tropical Wet/Dry Climates
Have pronounced wet and dry seasons, with high year-round temps.
Called savannas, have fewer plants and animals than tropical rain forest climates
Distinguishing characteristics is that sunlight is not blocked by trees and is able to reach ground
Makes for more specialized plant and animal species
Found in Africa, Central and South America

30. Dry Climates
The two main types of dry climates are semi arid (steppe) and arid (desert)
Occur in low latitudes and midlatitudes
Steppes are usually located away from oceans or large bodies of water and therefore are less humid
Receive inches of rain a year
Experience warm summers and harshly cold winters
Found on almost every continent and are home to a wide variety of grasses

31. Deserts
Extremely dry areas that receive 10 inches or less of rain per year
Usually hot and dry, although some experience snow in winter
In some desert areas, underground springs support an oasis, an area of lush vegetation
Very small amount of plant and animal life
Temps vary widely from day to night

32. Midlatitude and High-Latitude Climates
Midlatitude climates include four temperate climate regions: humid subtropical, marine west coast, Mediterranean, and humid continental
Experience variable weather patterns due to two conflicting air masses
Tropical air masses move from Equator to the Poles, and polar air move in opposite way

33. Humid Subtropical Climates
Include SE US as well as parts of Brazil, China, Japan
Characterized by short, mild winters and nearly year-round rain
High humidity levels
Vegetation consists of prairies and evergreen and deciduous forests
Coniferous tree, most of which are evergreens have cones
Deciduous trees, most of which have broad leaves, change colors and drop leaves

34. Marine West Coast Climates
British Isles, and Pacific coast of North America
Between 30 N and 60 N
Ocean winds bring cool summers and cool, damp winters
Abundant rainfall supports both coniferous and deciduous trees, resulting in mixed forests

35. Mediterranean Climate
Lands surrounding Mediterranean sea, sw coast of Australia, and central california
Have mild, rainy winters and hot, dry summers
Natural vegetation includes thickets of woody bushes and short trees known as Mediterranean shrubs

36. Humid Continental
Do not experience the moderating effect of ocean winds because of their northerly continental, or inland, locations
The farther north one travels, the longer and more severe are the snowy winters, and shorter cooler summers

37. High Latitude Climates
Freezing temperatures are common all year
Just south of the Arctic Circle are the subarctic climate regions
bitterly cold winters with short cool summers
Only a thin layer of surface soil thaws each summer
Below it is permafrost, permanently frozen subsoil

38. Tundra Closer to poles Winter darkness and bitter cold
Trees cannot establish roots, so vegetation is limited to low bushes, very short grasses, and mosses

39. Climate Change
Scientists have concluded that the average global temp has risen 1.4 F over last 100 years
Indicators include rising global temps, severe weather changes such as heat waves and changes in precipitation, increase in severe weather events and rising sea levels
While scientists argue about causes of climate change, we do know that Earth undergoes natural cycles of cooling and warming

40. Greenhouse Emissions
Burning fossil fuels releases gases that mix with water in the air, forming acids that fall in rain and snow
Acid rain can destroy forests
Fewer forests may result in climate change
Exhaust released from automobile engines and factories is heated in atmosphere by sun, forming smog, a visible chemical haze in the atmosphere

41. Questions Describe the Earth’s 4 climate zones?
What causes climate to change over time?
Why do high-latitude climates have limited vegetation?
How does burning of fossil fuels create smog?