Chapter 25 – Climate
Section 1: Factors That Affect Climate
Section 1 Objectives
Identify two major factors used to
describe climate
 Explain how latitude determines the
amount of solar energy received on Earth
 Describe how the different rates at which
land and water are heated affect climate
 Explain the effects of topography on
climate

Factors that Affect Climate
What is climate?
 How does it differ from weather?
 Climates are described using average
temp and precipitation.

◦ Daily: high and low of day / 2
 Monthly & yearly average temps
◦ Yearly temperature range

Latitude, heat absorption and release, and
topography affect temp and precipitation
Latitude
The higher the latitude, the smaller the
angle of incoming solar radiation on Earth’s
surface (equator receives more, translates
to higher temps)
 Also tilt of Earth leads to seasonal climate
change
 Different temperatures
different
pressures
wind belts
 Different wind belts lead to different
climates ~ affect temp, precip., & cloud
cover

Global Wind Belts
Doldrums – warm air rises and cools, water
vapor condenses, resulting in large amounts
of precipitation
 Subtropical highs (20-30) – air is sinking, it
warms and dries, little precipitation, most of
the world’s deserts here
 Middle latitudes (45-60) – warm tropical
air meets cold polar, belts of greater precip.
due to fronts
 Polar – cold, dry with avg. low precip.

Heat Absorption & Release
Land heats faster than water and can reach
higher temps in the same amount of time
 Ocean waters, waves, and currents circulate,
and as they warm the can move around and
be replaced by cooler water, takes longer for
overall ocean temps to increase or decrease
 Temp of land or ocean can affect how much
heat that the air above them absorbs or
releases and that air temp can affect climate
directly

Specific Heat & Evaporation
What is specific heat?
 Water has a higher sp. heat than land,
therefore it takes more energy to heat a
given mass of water to a certain
temperature than it does the same mass of
land
 Also, evaporation also affects water surfaces
at a much higher rate than land, and
evaporation cools the water and absorbs
energy away from water surface

Ocean Currents & El Niña
Temp of ocean current affects air above
water surface
 El Niño-Southern Oscillation (ENSO) – a
cycle of changing wind and water-current
patterns in the Pacific

◦ El Niño: the warm-water phase (La Niña, coolwater phase)
◦ Water temps along west coast of S. America rise
◦ Affects weather around the globe – typhoons,
cyclones, and floods or droughts
◦ Warm water keeps cold, nutrient-rich bottom
water from upwelling along coast. This in turn
affects fishing industries dramatically
Seasonal Winds
Winds between land and ocean can
change direction during different seasons
due to changing temperature imbalances
 Monsoons

◦ What direction do they blow in the summer?
◦ What type of weather do they bring?
◦ What about during winter?
Topography

What is topography?

What is a rain shadow?

How does it form?
Chapter 25 – Climate
Section 2: Climate Zones
Section 2 Objectives
Describe the three types of tropical
climates
 Describe the five types of middle-latitude
climates
 Describe the three types of polar climates
 Explain why city climates may differ from
rural climates

Three Major Climate Zones
Tropical
 Middle-latitude
 Polar


Each zone has distinct range of temps
◦ Several types of climates per zone because of
various amounts of precipitation.
Tropical Climates
Climates with high
temperatures in the
equatorial region
 Three types of
tropical climates

◦ Tropical rain-forest
◦ Tropical desert
◦ Savanna
Middle-Latitude Climates





Marine west coast
Steppe
Humid continental
Humid subtropical
Mediterranean
Polar Climates
Subarctic
 Tundra
 Polar icecaps

Local Climates

Microclimates
◦ Density of vegetation
◦ Elevation
◦ Proximity to large
bodies of water
◦ How do cities and
rural areas differ in
microclimate?
◦ Why?

What is a highland
climate?

What is the climate
like near a large body
of water?
Chapter 25 – Climate
Section 3: Climate Change
Section 3 Objectives
Compare four methods used to study
climate change
 Describe four factors that may cause
climate change
 Identify potential impacts of climate
change
 Identify ways that humans can minimize
their effect on climate change

Studying Climate Change
Climatologists – study climate change and
the cause of it
 They collect current climate conditions and
also use data from the past to predict future
changes

◦ Ice cores – concetration of CO2
◦ Sea-floor sediment – concentration of 18O
◦ Fossils – pollen type and leaf shapes; animal body
adaptations
◦ Tree rings – ring width (temp and precipitation)
Modeling Climates
Massive amounts of data are handled by
computers to help make models of climate
conditions
 General circulation models (GCMs)

◦ Can isolate variables and help us understand how
changes in individual factors may affect future
climates
◦ Very complex b/c they take into account
interactions between land, clouds, ocean, wind,
and vegetation
Potential Causes of Climate Change
Plate tectonics – changing wind flow and
ocean currents
 Orbital changes – Milankovitch theory

◦ Shape – distance from sun
◦ Tilt – difference in seasons
◦ Wobble – direction of tilt, reverses seasons

Human activity – pollution and deforestation
◦ Increases CO2

Volcanic activity – releases sulfur and ash
into atmosphere
◦ Decrease temps by reflecting solar radiation
Potential Impacts of Climate Change

Domino affect - one area’s climate change
could cause other to change.
◦ Affects not only humans, but all living things such
as plants and animals

Global warming – gradual increase in global
temps due to increased concentration of
certain gases in atmosphere
◦ Positive and negative effects, depending on
location

Sea-level changes – coastal cities might no
longer be habitable
◦ 50 % of the world population lives along coasts
What Can We Do?

Laws have been passed to reduce pollution
◦ Industrial processes are now monitored for
compliance with pollution laws

Reduce use of fossil fuels
◦
◦
◦
◦
◦
Turn off lights and appliances when not in use
Reduce use of AC and heaters
Recycle
Carpool
Hybrid cars