View the Gulf Stream currents on page 349 of your textbook

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SCIENCE ~ CHAPTER 9
CLIMATE
Miss Nelson
SECTION 1
What Causes Climate?
ANTICIPATORY SET
Differences in pressure, heat, air
movement, and humidity result in
changes of weather.
STANDARDS
S 6.4.a –
Students know the sun is the major source of
energy for phenomena on Earth’s surface; it
powers winds, ocean currents, and the water
cycle
S 6.4.e –
Students know differences in pressure, heat, air
movement, and humidity result in change in
weather
THE BIG IDEA
The main factors that influence
temperature are:
Latitude
Altitude
Distance from larger bodies of
water
Ocean currents
KEY TERMS
 Climate – the average long-term conditions of
temperature, precipitations, winds, and clouds
in an area
 Microclimate – climate conditions within a
small area that dif fer from those in the
surrounding area
 Marine climate – the climate of some coastal
regions, with relatively warm winters and cool
summers
 Continental climate – the climate of the centers
of continents, with cold winters and warm or
hot summers
KEY TERMS
 Ocean current – a large stream of moving water
that flows through the ocean in a regular
pattern
 Windward – the side of a mountain range that
faces the oncoming wind
 Leeward – he side of a mountain range that
faces away from the oncoming wind
 Monsoon – sea or land breeze over a large
region that changes direction with the seasons
WHAT CAUSES CLIMATE?
Scientists use two main factors
to determine climate:
Precipitation
temperature
FACTORS AFFECTING TEMPERATURE
Main factors that influence temperature
are:
Latitude
Altitude
Distance from large bodies of water
Ocean currents
LATITUDE
Review World Temperature Zones for the
effects of latitude on temperature
ALTITUDE
In the case of high mountains, altitude is
a more important climate factor than
latitude
As a result, highland areas everywhere
have cool climates, no matter what their
latitude
DISTANCE FROM LARGE BODIES OF WATER
 Oceans or large lakes can affect temperature
 Oceans make the temperatures of nearby land less
extreme (than they would be without the ocean)
 Water heats up more slowly than land
 Water cools down more slowly than land
 Winds off the ocean often prevent extremes of hot
and cold in coastal regions
OCEAN CURRENTS
 Marine climate are often influenced by ocean currents
 Some warm surface currents move heat from the tropics
toward the poles
 Affects climate as the warm ocean water warms the air above it
 The best warm water current is the Gulf Stream
View the Gulf Stream currents on page 349 of your textbook
FACTORS AFFECTING TEMPERATURE
Read Factors Affecting Temperature on pages
347 – 349 of your textbook
FACTORS AFFECTING PRECIPITATION
The main factors that affect
precipitation are:
Prevailing winds
The presence of mountains
Seasonal winds
PREVAILING WINDS
Weather patterns depend on the
movement of huge air masses
These air masses are move from place to
place by prevailing winds
The directional winds that usually blow in a
region
PREVAILING WINDS
Air masses can be warm or cool, dry or humid
The amount of water vapor in the air mass
influences how much rain or snow will fall
The amount of water vapor in the prevailing
wind also depends on where the winds come
from
 Winds that blow inland from oceans or large lakes
carry more water vapor than winds that blow from
over land
MOUNTAIN RANGES
A mountain range in the path of prevailing
winds can also influence where precipitation
falls
 When humid winds blow from the ocean to the
coastal mountains, they are forced to rise
 As they rise the air cools and its vapor condenses,
forming clouds
MOUNTAIN RANGES
The Sierra Nevada mountains have a major
effect on California’s climate
Extremely dry areas (such as Death Valley) are
located on the leeward side of the mountains
View Figure 4 on pages 350 – 351 of your
textbook
SEASONAL WINDS
 A seasonal change in wind patterns can affect
precipitation
 Sea and land breezes over a large region that change
direction with the seasons are called monsoons
 Thailand and parts of India receive much of their rain from the
summer monsoons
 Monsoon winds also bring rain to coast areas in West Africa
and northeastern South America
SEASONAL WINDS
Regions affected by monsoons receive
very little rain in winter
In the winter, the land cools and becomes
colder than the ocean
A “land breeze” blows from the land to the
ocean, which carries little moisture
SEASONAL WINDS
The Santa Ana winds are hot, dry winds that often
blow in Southern California during fall and early winter
 Cool air from the desert blows toward the coast
 As air flows down the mountain, it is compressed
and warms up
 The humidity of the air drops and vegetation dries
out, creating a potential fire hazard
FACTORS AFFECTING PRECIPITATION
Read Factors Affecting Precipitation on pages
350 – 351 of your textbook
THE SEASONS
The seasons are caused by the
tilt of Earth’s axis as Earth
travels around the sun
TILTED AXIS
 The axis is an imaginary line through Earth’s center
that passes through both poles
 The axis ALWAYS points in the same direction
 The north end of the axis is pointed away from the
sun for part of the year, and toward the sun for
another part of the year
View Figure 7 on page 353 of your textbook
EFFECT OF THE TILTED AXIS
 In June the northern hemisphere receives radiation (heat)
from the sun at a more direct angle
 In December, the north end of Earth’s axis is tiled away from
the sun
THE SEASONS
Read The Seasons on page 352 of your
textbook
CHECK FOR UNDERSTANDING
Define climate.
What are the factors that affect temperature?
CHECK FOR UNDERSTANDING
Define climate.
Cimate refers to the long-term, average
conditions of temperature, precipitation, winds,
and clouds in an area.
What are the factors that affect temperature?
The facts that affect temperature are latitude,
altitude, distance from large bodies of water,
and ocean currents.
MODELING / GUIDED / INDEPENDENT
Complete the Modeling, Guided Practice,
and Independent Practice Sections of your
Climate 9-1 Worksheet.
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