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.

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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Figure 1: Source: http://irjci.blogspot.com/2011/05/record-flood-levee-breach-lead-to-talk.html

Figure 2: Source: http://www.infozine.com/news/stories/op/storiesView/sid/47621/

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?

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 lithosphere as the crust and part of the upper mantle. All landforms are part of the lithosphere.

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Figure 3: Natural features affect people. Source: MC3 Project. Graphic organizer. SS060206.

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 slow-moving 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 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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Figure 4: The parts of the earth.Source: http://www.slideshare.net/tekart/chapter-1-14031116

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 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/

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Figure 5: The water cycleSource: http://water.usgs.gov/edu/watercycleshort.html

http://www.youtube.com/watch?v=5FooHD0atuc 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.

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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Figure 6: A volcanic eruptionSource: http://free-stock-illustration.com/pacaya+volcano+guatemala+tours

Figure 7: A funnel cloud is characteristic of tornadoes.

Source: http://www.wpclipart.com/weather/tornado/tornado_2.png.html

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.

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.

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Figure 8: Tornado prone areas of the worldSource: National Oceanic and Atmospheric Administration.

Figure 9 from MC3 Project. Graphic Organizer for SS060207.