Download Unit 2: The World in Spatial Terms (Lessons 6-7)

Unit 2: The World in Spatial Terms (Lessons 6-7)
Physical Features of Earth Create Challenges and Opportunities
The physical features of Earth create both challenges and opportunities for the
people living here. For example, many people in the United States have settled
in the area shown in the picture below. Yet, this area is likely to flood. Why
would people settle in a floodplain? Although prone to floods, the flat land along
the Mississippi River is fertile and good for farming. This land is a perfect
example of how a place can offer both challenges (floods) and opportunities
(farming) for the people living there.
Figure 1: Source: http://irjci.blogspot.com/2011/05/record-floodlevee-breach-lead-to-talk.html
Figure 2: Source:
http://www.infozine.com/news/stories/op/storiesView/sid/47621/
Since the physical features of Earth present challenges and opportunities for
people, they influence the way people live in different areas. People who settle
in a forest, for example, may find the land is difficult to farm so they may turn to
forestry as their main economic activity. People who live near an ocean are likely
to make a living fishing while people living on a plain would probably farm.
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The natural or physical features of
the earth affect how people live,
work, and play. People build their
homes, choose their clothing, and
grow their food differently based on
the physical features around them.
This is true for people around the
world. Can you think of how the
natural or physical features around
you affect how your family lives,
works, and plays?
Figure 3: Natural features affect people
Earth’s Physical Processes
The Earth is a dynamic place. The natural physical processes that created the
Earth’s physical features continue to affect Earth and its people. These natural
or physical processes are events that happen in nature and can be explained
scientifically. Physical processes are nature’s way of working. They produce,
maintain, or change the physical systems on the planet.
There are four components or parts of Earth’s physical systems: the
atmosphere, biosphere, hydrosphere, and lithosphere.
• The atmosphere is the layer of gases that surround the earth. The
earth’s atmosphere contains 78% nitrogen, 21% oxygen, 0.9% argon, and
0.03% carbon dioxide. The atmosphere redistributes heat and moisture it
receives from the earth’s surface.
• The lithosphere is the solid part of the earth. It includes all the rock and
soil on Earth. Technically, geologists and geographers define the
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lithosphere as the crust and part of the upper mantle. All landforms are
part of the lithosphere.
• The hydrosphere is the watery part of the earth’s surface. It includes
oceans, lakes, water vapor in the atmosphere, and polar ice caps. Water
found on, under, and over the planet’s surface make up the hydrosphere.
• The biosphere is the part of the earth and its atmosphere that is capable
of supporting life. From the polar ice caps to the equator, every part of the
earth’s surface features life of some kind. Thus, the biosphere contains
parts of the land, seas, and atmosphere in which living organisms exist or
that is capable of supporting life.
Earth’s physical processes can be organized based these four components.
Physical processes that operate in the atmosphere include climate and
meteorology. Climate is defined as weather over a period of time. For
example, the weather in Michigan changes from season to season, but the
climate in Michigan is defined as temperate.
Physical processes in the
lithosphere include plate tectonics,
soil erosion, and soil formation. A
tectonic plate is a massive slab of
solid rock that “floats.” Scientists
believe that tectonic plates
probably developed very early in
the Earth's 4.6-billion-year history,
and they have been drifting about
on the surface ever since-like slowmoving bumper cars repeatedly
clustering together and then
separating. When they move, they
can cause changes on the earth’s
surface. As the plates move they
Figure 4: The parts of the earth.
shape the physical features of the
earth. Physical processes on the earth’s surface include earthquakes,
volcanic eruptions, soil formation, and soil erosion.
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In the hydrosphere,
physical processes
include the water
cycle, wave action, and
the circulation of the
oceans. Evaporation,
condensation, and
precipitation are all
part of the water cycle.
Evaporation is when
liquid turns to gas.
Condensation is the
process when gas
cools and turns to
liquid. This is different
than precipitation.
Precipitation occurs
Figure 5: The water cycle
when any form of
water falls from the sky. Rain, mist, hail, sleet and snow are precipitation.
The physical processes of the hydrosphere can change the earth’s surface. Rain
water can erode mountains. Water in the form of glaciers can modify the earth’s
surface by creating lake basins, such as the Great Lakes.
The biosphere also has physical processes that result from living organisms.
Photosynthesis and decomposition are two physical processes of the biosphere.
Photosynthesis is the process by which plants convert light energy from the Sun
into chemical energy that can be used by plants. Decomposition occurs when a
dead plant or animal is broken down into smaller particles that can be used by
other organism. The biosphere -- the location of all living organisms on Earth – is
affected by the processes in the atmosphere, lithosphere, and hydrosphere.
To learn more about the physical processes of the earth:
• http://prezi.com/yxgpz2zgvkt-/physical-processes-that-shape-earth/
• http://www.youtube.com/watch?v=5FooHD0atuc
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Natural Hazards
When natural physical processes are
unpredictable and have a negative effect on
people or the environment, we call it a natural
hazard. Some examples of natural hazards
are tornadoes, tsunamis, tropical cyclones,
earthquakes, volcanic eruptions, floods,
droughts, landslides, and wildfires.
Figure 7: A funnel cloud is characteristic of
tornadoes.
Figure 6: A volcanic eruption
Many natural hazards are interrelated. For instance, an earthquake on the ocean
floor can cause a tsunami. Hurricanes can lead to erosion and coastal flooding.
Not all areas of the world are equally at risk of experiencing the same natural
hazards. Since hurricanes, typhoons, and cyclones occur in the ocean, a
landlocked area would be less likely to have to deal with the effects of one of
these events. Similarly, tornadoes are more likely to occur in flat areas.
Mountainous regions are not as prone to tornadoes.
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The map below shows areas of the world that are most likely to experience
tornadoes. The areas highlighted in red would have to prepare and plan
differently than those where the risk is significantly lower. By studying the
patterns created by natural hazards, scientists can better understand and
prepare people for natural hazards.
Figure 8: Tornado prone areas of the world
Natural hazards are a good example of human environment interaction. These
naturally occurring events can have a significant impact on the people living in a
specific area. Oftentimes, geographers will use the geographic inquiry process
after a natural hazard to try and determine what the people in a specific location
could do to be better prepared the next time a similar event occurs.
Figure 9
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