Transcript Chapter 21

Chapter 14
Climate
“Want to trade places?”
What is Climate?
Climate is the composite or generally prevailing weather
conditions of a region, as temperature, air pressure, humidity,
precipitation, sunshine, cloudiness, and winds, throughout the
year, averaged over a series of years.
 In other words Climate is determined by a series of
weather data collections, of a specific region, over a
period of time ( at least 30 years)
-How is climate different than weather???
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Weather – the state of the atmosphere at any given
time or place (DAILY DATA COLLECTION)
CLIMATE
Koeppen’s Climate
Classification System
In 1920, Wladimir Peter Köppen
developed a classification system for
climates based only on
precipitations and temperatures.
 The world is divided into 5 major
climatic zones based upon this
classification system.
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Koeppen System
Chart Layout
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http://geography.about.com/library/weekly
/aa011700b.htm
What Determines Climate?
Two of the most important factors
determining an area's climate are
air temperature and precipitation.
 Example: Located in northern South
America,Venezuela has a tropical climate.
 Why is this country considered Tropical?
-Tropical climates have an annual rainfall of
250 cm or more and an average
temperature of 80˚F.
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VENEZUELA
6 Things that Affect Climate
1.
Latitude – distance North or South
of the Equator
◦ Higher latitudes, colder climate
2.
Elevation – distance above sea level
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3.
Higher elevation, colder climate
Topography – the lay of the land
◦
Mountains play an important role in the
amount of precipitation that falls on an area
6 Things that Affect Climate (cont.)
4.
5.
6.
Water Bodies – lakes and oceans
affect the temperature of the air
above them
Atmospheric circulation – global
winds distribute heat and moisture
around Earth
Vegetation – plants affect the amount
of the sun’s energy is absorbed and
how quickly the energy is released
◦
Transpiration – releases water vapor into the
air
Natural Processes Change Climate
1.
Volcanic Eruptions
◦
2.
Ocean Circulation – can result short term
climate fluctuations
◦
3.
4.
Volcanic ash and dust reflect sunlight back into space
(causes the Earth’s surface to cool)
El nino and La nina
Solar Activity – variations in solar activity
can cause short term climatic change
Changes in the Earth’s motion –
◦
tilt, precession, orbit
Human Impact on Climate Changes
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The Greenhouse Effect – a natural
warming of both the Earth’s lower
atmosphere and surface
◦ The sun’s light goes through the Earth’s
atmosphere and heats up the land
◦ The land then radiates the heat back into the
atmosphere
◦ The lower atmosphere traps the heat making
it warmer
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Allows humans to live on Earth
Historic CO2 Emissions
Human impact on the Greenhouse
Effect
 Carbon
Dioxide levels have increased in
our atmosphere since 1850
◦ The industrial revolution
◦ Burning fossil fuels increase the
amount of CO2 in the atmosphere
◦ Cutting trees also increases the
amount of CO2 in the atmosphere
 CO2 released when plants are burned
 Plants use CO2 to make food
Global Warming

Global temperatures have increased due
to more CO2 and other greenhouse
gases in the atmosphere
◦ Earth’s surface temperature has increased 0.6°C
during the 20th century
◦ Predicted: by the year 2100 surface temperatures
will increase by 1.4°C to 5.8°C
 Will lead to sea ice melting and a rise in sea levels
 Sea ice reflects sunlight and will increase the amount of
heat in the atmosphere
Global Warming

The hotter the temperatures, the more
the climate changes, leading to natural
disasters all over the world, from wild
fires and flooding to long-term drought.
Sea levels are rising from melting ice
sheets. Warmer air and ocean
temperatures are endangering many
animal and plant species unable to
adapt to such rapid changes.
CFC’s-Chlorofluorocarbons
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Compound consisting of chlorine, fluorine, and
carbon
CFCs are very stable in the troposphere.
They move to the stratosphere and are broken down
by strong ultraviolet (UV) light, where they release
chlorine atoms that then deplete the ozone layer.
CFCs are widely used as coolants in refrigeration and
air conditioners, as solvents in cleaners, particularly
for electronic circuit boards, as a blowing agents in
the production of foam (for example fire
extinguishers), and as propellants in aerosols.
Indeed, much of the modern lifestyle of the second half of
the 20th into the 21st century had been made possible by the
use of CFCs.
Ice Age and El Nino (Climatic events)
•Ice Ages occur when Earth’s
climate experiences an extreme
drop in temperature.
The Facts:
•There were about 11 different ice
ages.
•The ice ages were during the
earth's 4.6 billion years of history.
•The last ice age was called "The
Great Ice Age" and was 11,000
years ago.
•During the "Great Ice Age" over a
third of the earth was covered in
ice. During the ice age the air had
less carbon dioxide in it.
Ice Age Continued
Right now we are living in a mini ice age.
• There are two explanations of why the
ice ages might have occurred:
1.The temperatures were much colder so
it never rained, only snowed.
2. The earth changed its tilt away from the
sun.
•
El Nino and La Nina
El Nino-Abnormal warm ocean water
temperatures that occasionally develops
off the western coast of South America
and can cause climatic changes across the
Pacific Ocean. Brings warm temps and
rain
 La Nina- Opposite of El Nino it brings
colder temperatures along the
equator.According to scientists, La Niña
cycles generally create a more active
hurricane season in the Atlantic
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