Geography Standard Two: Students will develop a knowledge of the ways humans
modify and respond to the natural environment.
Part I
If you have ever traveled to Florida or California, you already understand that climates
(the general or average weather conditions of a certain region, including temperature,
rainfall, and wind) are not the same in all parts of the world. Some places receive more
precipitation (rain), and some places have warmer or colder temperatures than others.
Latitude is the biggest determinant of a location’s temperature and climate. Lines of
latitude are imaginary lines that run across the earth from east to west. The most famous
line of Latitude is the Equator, circling the earth halfway between the poles. Although
latitude lines run east to west, they are used to tell how far north or how far south a
location is from the Equator. The distance from the equator is measured in degrees going
from 0 to 90.
The North Pole is at 90N.
Notice how
latitude runs
from east to
west around
the globe, but
tells how far
north or
south a
location is.
Here is 45N. Do
you notice how it is
halfway between the
North Pole and the
Equator?
The Equator
is located at
0. The
further away
you go from
it, the colder
the climates
become.
South Pole at 90S
Generally, the further north or south a location is from the equator, the colder its
temperature becomes. The reason is that the Earth around the equator, between the
Tropic of Cancer and the Tropic of Capricorn, receives more direct sunlight all through
out the year. The areas near the Equator are called the Tropical Regions. A good way to
remember this is to think of Tropicana orange juice. You can only grow oranges in
tropical or very warm regions.
The areas near the North and South Poles are known as the High Latitudes or Polar
Regions. These areas experience very cold temperatures during winter, and large
variations or differences in their hours of sunlight. During the winter, there are 24 hours
of darkness. In the summer, the sun never sets. The areas in between the high latitudes
and the tropics are the earth’s temperate zones. These areas experience four seasons.
High Latitude
or Arctic
Middle
Latitudes
or
Temperate
Zones
Tropical
Areas
Even though it is
at the bottom of
the map, the South
Pole has a high
latitude of 90S
Another major cause of a location’s climate is its altitude or elevation. The higher
above sea level a place is, typically the colder it becomes because of the thinner air. That
is why many mountains are capped with snow and ice.
In general, places close to large bodies of water are warmer in the winter and cooler in
the summer than inland locations away from water. This is because the water stores heat
from the sun during the summer and releases it in winter, warming the air. On the other
hand, places near the middle of continents can experience extremely cold winter
temperatures, while the summers can bring sizzling heat waves. Wind currents like the
Jet Stream and water currents like the Gulf Stream can also have a big effect on climate.
Part II
Plants, animals, and humans adapt to their climate and physical environment in various
ways. Animals may grow a heavier coat in winter, change color with the changing
seasons, or migrate to find more reliable food sources as the seasons change. Plants can
become dormant during the winter season or conserve water in their roots. Humans wear
lighter clothing in hot weather, build houses with heating systems, and select crops that
do well in local conditions. A look at the world population distribution map shows that
most people choose to live in areas with a moderate climate, a reliable water supply, and
near farming regions for a food supply. It is easier to adapt to the physical conditions in
these areas.
Few Humans live
in Northern
Canada and
Greenland because
the cold climate is
bad for farming.
Over 1/3 of the
world’s people
live in either
India or China.
Each dot
equals 100,000
people.
On each
continent, you
can see how
people prefer
coastal areas.
But increasingly, people and their projects alter or change the environment, and the
actions they take have consequences. Where you are right now, was likely once
woodland. Is it now? No, because humans have altered, modified, or have changed the
environment. Have you ever seen a dam? Dams are obvious examples of humans
modifying an environment. The lake formed behind the dam makes it evident that the
dam has altered the natural flow of the river.
Dams, bridges, roads, and other large projects can yield benefits to humans. But they can
also pose dangers to people, wildlife, and ecosystems. For example, if a cattle rancher
affects an environment by allowing his or her cattle to eat all of the grass in a location, he
or she has altered that environment. Without the grass, the environment will no longer be
able to hold in as much water, and the roots of the grass that keep the soil together will be
missing (the cows ate them all). The consequence of this overgrazing could be that
grassland will dry up and even become a desert (desertification). With no grass to hold
the soil together, the wind could erode the soil in the form of a dust storm.
While humans often alter the environment to suit their needs, physical/ natural
environments sometimes constrain and even endanger humans. Violent hurricanes,
tornados, coastal storms, floods and blizzards often put people in danger. Volcanic
eruptions, earthquakes, and tsunamis devastate whole communities. Similarly, arctic
climates might constrain people from living there because of the living difficulties
associated with the extremely cold climate.
Humans react to an area based on how they perceive their environment. People who
perceive volcanoes as highly likely to erupt choose not to live near them. But people
who think of volcanoes as a source of rich soil might even live on the side of one. These
people perceive the benefits of their location as greater than the risks. Similarly, people
who live in the Caribbean judge that the beautiful beaches and balmy breezes they
experience most of the year are worth the risk of hurricanes.
Part III
The earth’s environment is a set of interconnected (mutually joined or related) systems
(ecosystems). A system is a set of interconnected parts that are logically connected. To
better understand this, start off by thinking of a home entertainment system. What might
it have? A TV, a DVD player, a stereo, maybe a Playstation. All these parts are
connected to form an entertainment system. They function best when together, and their
function is to entertain.
Part IV
It is easy just to say that cutting down trees is bad for the Environment. However, can
you really explain why? Cutting down trees, or deforestation, is bad for the environment
because it disrupts an environmental process. By clearing the forests, humans are
reducing the number of trees that can turn carbon dioxide, or CO2, into oxygen through
the process of photosynthesis.
Now let’s look at an environmental system, the Carbon/Oxygen Cycle. In the cycle,
humans (who fall under plant and animals) breathe in the oxygen that green plants
breathe out through (photosynthesis). Conversely, the green plants breathe in the carbon
dioxide that humans breathe out. It is a little more complicated, but that is the idea.
Things get interesting because humans have modified or altered their environment by
cutting down thousands upon thousands of square miles or woodlands (deforestation) in
order to use the land for things such as farming and housing. This modification has
caused an unbalance in the cycle. Because there are fewer trees to produce oxygen, there
is an increase in the level of C02 in the air, a possible cause to Global Warming.
When trees are
cut down, the
cycle is
unbalanced, and
has more and
more carbon
dioxide, but less
oxygen.
Factories and cars
use oxygen but
emitting more CO2,
creating an
imbalance.
Plants (only a
little) and
animals (like
humans)
breathe in
oxygen, but let
out carbon
dioxide.
Part V
Another interesting process that humans have modified is the naturally occurring
flooding of some rivers. Many rivers, such as the Nile in Egypt, once a year receive
tremendous amounts of extra water because of rainy seasons happening where the river
begins. This extra water caused the river to flood on a predictable yearly basis. Once a
year, for thousands of years, Nile’s water rose above the riverbed and flooded the
surrounding area. When the water would later evaporate, it left behind rich soil deposits
that made farming easy along the Nile since the times of the Pharaohs and Pyramids.
However, the floods would also damage much property, so Egyptians dammed the river
so that they could stop the flooding. The damming of the Nile disrupted the natural
process of the river fertilizing the soil. Therefore, a consequence of humans altering the
environment this way is that the river no longer provides the rich soil on a yearly basis,
and farmers now have to buy man-made fertilizers.
When a
countries’ border
is a straight line,
then it typically
was determined
by latitude or
longitude, and is
a man made
border, unlike a
river or
mountain range.
Using the
key, you
can see that
Egypt’s
population
is most
dense
around the
Nile River.
Part VI
Another process, one that humans have adapted to more than they have modified, is the
physical process of Plate Tectonics. Geographers believe that the Earth’s crust is not
completely solid, but made up of many different sections or plates. This theory, the
Theory of Plate Tectonics, also asserts that the plates are constantly, but slowly,
moving. The plates are moving because of the different densities of the plates and
pressure from the heat within the earth’s core.
Where plates meet, because of the plates’ movement, certain natural phenomenons occur
such as mountain building, volcanoes, and earthquakes. Where plates collide, mountains
form. The denser plate submerges under the lighter plate, and pushes the lighter plate up
to form mountains. The more triangular or pointed the mountains are, the more recently
the mountains have formed from this process. Some mountains like Mount Everest, the
world’s highest mountain, are still rising. Older mountains have rounded tops because
they have had more time for gravity, and both water and wind erosion to level or flatten
them out. Where plates separate and pull apart, earthquakes and volcanoes occur. When
the plates move apart, the earth’s surface is often ruptured and lava either flows or erupts
out in a volcanoes.
The Ring of Fire, shown in the map above, surrounds the Pacific Ocean and is found in
four different continents. The Ring of Fire earned its name because of the fact that within
the shaded area above are 90% of the world earthquakes, and 80% of the world’s
volcanoes. These percentages show that earthquakes and volcanoes occur near the edges
of tectonic plates.