Chapter 25.1
“Factors that Affect Climate”
Modified from many sources & Holt CA Earth Science
by L. Smith
Factors That Affect Climate
CLIMATE = The AVERAGE weather
conditions over a LONG period of time
CLIMATE = WEATHER
Factors That Affect Climate
CLIMATE = most often described by:
AVERAGE TEMPERATURE
and
ANNUAL PRECIPITATION
Factors That Affect Climate
I.
Latitude
II. Heat Absorption & Release
III. Topography
Factors That Affect Climate
I.
Latitude
• The sun’s rays strike the equatorial
region at a much more direct angle
than the poles, making the average
temperature at the poles much colder
and the average temperature at the
equator much warmer.
Latitude
http://www.geogrify.net/GEO1/Lectures/EnergyAtmosphere/SolarEnergy.html
• Solar energy striking the Earth’s surface
near the poles is less intense than radiation
striking the Earth near the equator.
Latitude
Latitude
Global Wind Patterns
Differing amounts of
solar energy, and the
spinning of the Earth,
create different wind
patterns at different
latitudes .
Latitude
Global Wind Patterns
Wind patterns at
different latitudes
then influence
precipitation
patterns.
Factors That Affect Climate
II. Heat Absorption & Release
• Different surfaces heat and cool at
different rates creating wind patterns
and ocean currents.
Heat Absorption & Release
Land vs. Water
The differential
heating and cooling
of land and water
creates winds.
Land heats AND
cools faster than
water.
Heat Absorption & Release
Specific Heat & Evaporation
Specific heat is the amount of energy
required to raise the temperature of a
substance 1 degree C.
Heat Absorption & Release
Specific Heat & Evaporation
Water requires a larger
amount of energy to
increase temperature
than most substances.
Evaporation of water
absorbs a lot of energy
too (think sweat!).
Heat Absorption & Release
Ocean Currents
Ocean currents
can have a
large influence
on air masses
over the land
they contact.
http://geology.uprm.edu/Morelock/2_image/ocncur.jpg
Heat Absorption & Release
El Niño Southern Oscillation
• El Niño - the name given to the periodic
warming of the ocean that occurs in the
central and eastern Pacific.
• At irregular intervals of 3-7
years, these warm countercurrents
become unusually strong and replace
normally cold offshore waters with warm
equatorial waters.
Heat Absorption & Release
El Niño Southern Oscillation
• A major El Niño episode can cause extreme
weather in many parts of the world.
Increase precipitation and landslide
activity in southern California and the
Southwest
Drought to the northern Rocky
Mountains
Heat Absorption & Release
Normal Conditions
Heat Absorption & Release
Normal Conditions
Normally, strong trade winds blow from the east
along the equator, pushing warm water into the
Pacific Ocean.
Heat Absorption & Release
El Niño Conditions
Heat Absorption & Release
El Niño Conditions
An El Niño condition results from weakened
trade winds in the western Pacific Ocean near
Indonesia, allowing piled-up warm water to flow
toward South America.
Heat Absorption & Release
La Niña
• Researchers have come to recognize that
when surface temperatures in the eastern
Pacific are colder than average, a La Niña event
is triggered that has a distinctive set of
weather patterns.
Droughts in parts of the South and
Southwest from Arizona to Arkansas and
Louisiana
Above normal precipitation in the
Northwest and the Tennessee Valley area
Heat Absorption & Release
Seasonal Winds
Monsoons are the
seasonal reversal
of wind direction
associated with
large continents,
especially Asia
(which affects the
Indian subcontinent).
http://www.mrdowling.com/images/612monsoons.png
Heat Absorption & Release
Monsoons
•
In summer, the
wind blows
from sea to
land.(wet)
• In winter, the
wind blows
from land to
sea.(dry)
http://volney-bodley-weather-
Monsoon Photos
More about monsoons--click here
Factors That Affect Climate
III. Topography
• Topographic features such as
mountains play an important role in
the amount of precipitation that falls
over an area.
Elevation
Topography
Elevation is height above sea level
Temperature generally decreases as elevation
increases.
The Rain Shadow Effect
As humid air on the windward side of the
mountain moves up the slopes it cools,
condenses, and forms clouds and rain.
By the time the air reaches the leeward side of
the mountain, most of the moisture is lost.
The Rain Shadow Effect
RAIN
SHADOW
http://classconnection.s3.amazonaws.com/436/flashcards/774436/jpg/picture11320597452956.jpg
The dry area on
the leeward side
of the mountain
is called a rain
shadow.
The Rain Shadow Effect
http://www.geography.hunter.cuny.edu/~tbw/wc.notes/15.climates.veg/climate/B ...
The Rain Shadow Effect
The dry area on
the leeward side
of the mountain
is called a rain
shadow.
http://www.sierranevadaphotos.com/geography/sierra_precipitation.asp
Climate Data for Two Cities
This climate graph shows
data for two cities, both
located in Arizona.
Phoenix has an elevation
of 338 m and Flagstaff has
an elevation of 2134 m.
• How does the elevation
affect the annual
temperature and
precipitation?
• What causes this
difference to occur?
Other Factors That Affect Climate
IV. Bodies of Water
• Large bodies of water,
such as lakes and
oceans, alter the climate
of an area.
• Places downwind of a
large body of water
generally have cooler
summers and milder
winters than places of
the same latitude that are
further inland.
Other Factors That Affect Climate
IV. Bodies of Water
• Coastal areas (or areas near large
lakes like the Great Lakes)
generally have more precipitation
than inland areas.
http://quizlet.com/15961300/print/
Other Factors That Affect Climate
V. Atmospheric Circulation
• Global winds are
another factor that
influences climate
because they
distribute heat and
moisture around
Earth.
Other Factors That Affect Climate
V. Atmospheric Circulation
• Low-pressure zones
at the equator and in
the sub-polar
regions form clouds
that drop much more
annual precipitation
in the form or rain or
snow depending on
the average
temperatures of the
area.
http://www.weatherwizkids.com/globalcirculation.gif
Other Factors That Affect Climate
V. Atmospheric Circulation
Notice the cloud cover over the equator
(equatorial low) and clear skies over the tropics
(subtropical highs.)
Other Factors That Affect Climate
VI. Vegetation
• Vegetation can affect
both temperature
and precipitation
patterns in an area
by influencing how
much of the Sun’s
energy is absorbed
and how quickly this
energy is released.
Other Factors That Affect Climate
VI. Vegetation
• Plants release water
vapor through their
leaves into the air via
transpiration.
• Vegetation also
releases particles that
act as cloud seeds
and increase
precipitation.
http://vjh.flbsd.mb.ca/wp-content/uploads/2012/08/transpiration.jpeg