1. The bottom-line is that it is very difficult to convince Americans that the planet is facing
an impending environmental crisis. As the world’s greatest consumer & polluter, the U.S.
will have to lead the international community to a consensus.

5. EL NINO
El Nino is a Pacific Ocean current with worldwide climatic effects. Next to the seasons, El Nino is the
most powerful force driving global weather. Normally the Humboldt Current, an extensive cold ocean
current, provides the coast from southern Ecuador to northern Chile with a cool, misty, virtually rain-
free climate.

6. In normal years, the flow of the Humboldt Current is strongly maintained by the counterclockwise
wind flow around the South Pacific. These winds blow northward along the coast, inducing a flow of
cold water originating off the coast of Antarctica. The winds, as they approach Peru’s latitude,
gradually are redirected westward as they are incorporated into the southeast trade winds. The
westward movement of the surface water causes large volumes of cold water to well up from great
depths. The water level drops along the S. American coast and rises in the tropical west Pacific.

7. For reasons still mysterious to
scientists, wind direction shifts,
causing the Humboldt Current to
reverse its flow to a clockwise
direction every 5-7 years.
The warm water that has
accumulated in the western Pacific
no longer is pressed against Asia
and surges eastward in a series of
waves.
It crosses the Pacific to produce a
southward flow of tropical water
down the S. American coast and
northward along the Central &
North American western
coastlines.
Sea levels rise & temperatures
rise as much as 14.5 degrees. This
is El Nino.
On average, an El Nino occurs
approx. every 5-7 years.

8. The most recent El Nino occurred in the late 1990’s. Throughout the years,
they have varied in strength and length, although they generally endure for
two years. The consequences of each have been widespread and locally
disastrous. The effects are generally felt most strongly in the immediate
vicinity. In the U.S., the effects range from severe storms along the west
coast to drought conditions in the northeastern and mid-western portions of
the country.

9. For the southeastern U.S. and Central America, an El Nino will magnify hurricane season,
meaning more hurricanes that are more powerful.
The other major effect of an El Nino includes a disruption of the food chain for fish and
their predators (commercial fishing is effected). Associated weather calamities affect
every continent except Antarctica & Europe. The more recent El Ninos cause thousands
of deaths and billions of dollars in damage.

11. LAND & CLIMATE
FACTORS AFFECTING CLIMATE
Latitude is the most prominent factor affecting climate. The Earth’s shape and tilt
affects the angle of the sun’s rays, thus affecting climate.

12. ELEVATION
Even in the tropics, elevation can
create a frigid climate.
For every 1,000 feet above sea
level, the temperature drops
approx. 3 degrees.

13. WIND & OCEAN CURRENTS
The source and direction of wind influences the climate of a given region. An excellent
example of this phenomenon is the monsoon seasons of South Asia.

14. Cold and warm currents of seawater greatly influence the climate of coastal areas. What
is the biggest impact of these ocean currents?

15. LANDFORMS
Prominent mountain ranges greatly impact climate, especially rainfall amounts. Examples
include the Atlas Mountains in North Africa and the Rocky Mountains in the U.S.

16. NATURAL PHENOMENON &
HUMAN ACTIVITY
In the short term, natural phenomenon, such as volcanic eruptions, can alter climate.
Human activities, including recreational and economic, can have longer-term consequences
on climate.

17. WORLD CLIMATE ZONES

18. LOW LATITUDE CLIMATES
The first type of low latitude climate is humid tropical,
better known as tropical rainforest.
Provide the geographic distribution, major weather
characteristics, and vegetation.

19. The other low latitude climate is tropical savanna. Provide the geographic distribution,
weather characteristics, and vegetation. Identify the major differences between
the two tropical climates.

20. DRY/SEMI-ARID CLIMATES
The first climate type in this category is desert. Provide the geographic distribution,
major weather characteristics, and vegetation.

21. The second climate type in this category is steppe. Provide geographic distribution,
major weather characteristics, and vegetation.

22. Causing growing concern among geographers is the phenomenon of desertification, where
steppe areas are growing and desert areas are moving into steppe areas. Causes include
natural phenomenon (drought/global warming) and human activity (deforestation & over-
grazing).

23. MIDDLE LATITUDE CLIMATES
The Mediterranean climate is one of four climates found in this category. Provide
geographic distribution, major weather characteristics, and vegetation.

24. Another middle latitude climate is the humid-subtropical. Provide the geographic
distribution, major weather characteristics, and vegetation.

25. The humid continental climate zone encompasses the area in which we live. Provide the
geographic distribution, major weather characteristics, and vegetation.
The marine west coast climate zone rounds out the middle latitude climates. Provide the
same characteristics for this climate zone.

26. HIGH LATITUDE CLIMATES
The three climate zones included in this category include subarctic, tundra, and ice cap.
Provide the geographic distribution for each, major weather characteristics, and
vegetation.

27. The climate zone that is unique because it can be found at most latitudes is the highland
climate zone. Provide the geographic distribution, major weather characteristics, and
vegetation.