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Themes of Physical Geography Landforms Climate Human Environment Interaction Interaction I. Landforms and The Forces that Shape our Planet A. Internal Forces B. External Forces C. The Landforms they Create II. Climate A. Earth Sun Relationship B. Factors Affecting Climate C. World Climate Patterns III. Human Environment interaction A. How do we use our Planet? B. How have we altered our Planet? C. How have we adapted to our Planet? Landforms I. The Forces that Shape our Planet A. Internal Forces B. External Forces C. The Landforms they Create The Forces that Shape our Planet Internal Forces of Change The earth is about 24,900 miles in circumference . Although the earth seems like a solid ball, it is really more like a series of shells that float on one another. Core – solid metallic center made of nickel and iron Mantle – soft layer of molten rock (magma) Crust – thin layer of rock on earth’s surface The internal forces that shape the earth’s surface begin just beneath the crust. Heated magma moves up toward the crust, cools, and circulates downward. Riding above this circulation system are the tectonic plates. The plates are enormous moving pieces of the earth’s crust. Alfred Wegener first presented the theory of Continental Drift . He claimed that in Earth’s early existence there was only one body of land, Pangaea. That supercontinent then slowly split and separated into the continents we see today. When plates meet, they may cause folding and cracking of rocks. This fracture in the earth’s crust is called a fault. It is at the fault line that plates move past each other. Divergent Boundary Where plates move apart or spread, creating rift valleys or seafloor spreading. Convergent Boundary Where plates come together . Can cause folding or subduction zones Transform Boundary Where plates slide past one another. The Ring of Fire, a huge ring of volcanic and seismic (earthquake) activity, was noticed and described before the invention of the theory of plate tectonics theory. Today we now know that the Ring of Fire is located at the borders of the Pacific Plate and seven other major tectonic plates. It is home to 75% of the worlds Volcanoes and 90% of the world’s earthquakes. The Forces that Shape our Planet External Forces of Change Weathering refers to the physical and chemical processes that change the characteristics or rocks. Sediment = smaller pieces of rock Mechanical Weathering is the process that breaks rock up into smaller pieces. Examples: Roots, Ice, Gravity, Human Processes Chemical Weathering occurs when rock is changed into a new substance as a result of interaction between elements in the air or water and the minerals in the rock. Examples: Acid Rain, Oxidation (rusting) Erosion occurs when weathered material is removed by the action of wind, water, ice, or gravity. Water Erosion As water flows in a stream or river, it picks up loose material and moves it downstream. The force of a swift flowing river carrying sediment is enough to carve its way through rock forming a canyon. When a river enters the ocean, sediment is deposited into a fan-like landform called a delta. Wave action along coastlines also changes the land. Waves may build up beaches, or carry them away. Wind Erosion Wind erosion is quite similar to water erosion. The wind transports sediment and deposits it in other locations. Sand dunes are formed in this manner. The sediment carried in the wind may impact on solid objects causing erosion by abrasion. This can sculpt rock into columns and arches. Glacial Erosion Glaciation is the changing of landforms by slowly moving glaciers. A glacier is a large, long-lasting mass of ice that moves because of gravity. Glaciers form in mountainous areas and in regions that are regularly covered with heavy snowfall and ice. On top of the glacier or inside it are other rocks. When the ice melts, these are left behind. Rocks left behind by a glacier may form a ridge or a hill. As a glacier moves it can carve flat plains or valleys. Sometimes blocks of ice are trapped in the sediment. They melt slowly and leave a depression called a kettle lake. The Forces that Shape our Planet The Landforms they Create Landforms are naturally formed features on the earth’s surface. Archipelago - a group of many islands Basin – a depression in the ground Bay - part of a body of salt water that reaches into the land; usually smaller than a gulf Canal - a man-made waterway connecting two bodies of water, designed to shorten travel time or irrigate Canyon - narrow valley with steep sides; usually created by erosion Cape - a curved or hooked piece of land extending into a body of water Channel - a narrow deep waterway connecting two larger bodies of water; the deepest part of the waterway. Delta -land built up by deposits of sand and silt at the mouth of some rivers Divide -the highest ridge of land separating river basins Gulf - part of a sea or ocean that reaches into land; usually larger than a bay Harbor - a sheltered area of water where ships may anchor safely Highland - an area of hills, plateaus, and mountains Island - an are of land completely surrounded by water Isthmus - narrow strip of land with water on both sides connecting two larger pieces of land Lake - a large body of water surrounded by land Mesa - a land formation having a relatively flat top and steep rock walls Mountain - high, rocky land, usually with steep sides and a pointed or rounded top, higher than a hill Mouth (of a river) - place where a river empties into a larger body of water; the end of a river Oasis - a fertile place in the desert where there is water and some vegetation Ocean - largest body of salt water; these cover 3/4 of the earth’s surface. Peninsula - piece of land that extends into a body of water and is surrounded on three sides by water Plain - a broad, flat or gently rolling area; usually low in elevation Plateau - flat highland area with one steep face; elevated plain River - a large stream of water flowing through the land into a lake, ocean, or other body of water Sea - a large body of water, usually salt water, partly or completely surrounded by land Source (of a river) - the place where a river or stream begins Strait - a narrow waterway connecting two larger bodies of water Swamp - an area of land that is always soaked with water; low, wet land that supports grass and trees Valley - low land between hills or mountains Volcano - a cone shaped mountain formed out of rock or ash thrown up from inside the earth, frequently with an opening or depression at the top Waterfall - place where running water makes a sheer drop, usually over a cliff Topography – Is the combination of the surface, shape, and composition of the landforms and their distribution in the region. Elevation is the distance above sea level. It answers the question “How high is it? Relief is the difference in elevation of a landform from its lowest point to its highest point. It answers the question “How tall is it? The highest spot on earth is Mt Everest. The deepest is Mariana Trench. Climate II. Climate A. The Earth Sun relationship B. Factors Affecting Climate C. World Climate Planet Climate The Earth Sun Relationship The earth tilts at a 23.5° angle in relation to the sun. This causes the changing seasons. Solstice – longest and shortest days of the year (occurs in winter and summer) June & December 21 Twice a year on the equinox, the days and nights all over the world are equal in length. The equinoxes mark the beginning of spring and autumn. September & March 21 Climate Factors Affecting Climate Weather - the condition of the atmosphere at a particular location and time. Climate - weather conditions at a particular location over a long period of time. Weather is the result of several factors. Large masses of air absorbs and distributes solar energy. Clouds hold water vapor. Water vapor in the atmosphere can become precipitation—falling water droplets in the form of rain, sleet, snow, or hail. Convectional precipitation -occurs in hot moist climates where the sun quickly heats the air. Wind and ocean currents help distribute the sun’s heat from one part of the world to another through convection - the transfer of heat in the atmosphere by upward motion of the air. Global wind patterns are caused by the same kind of circulation on a larger scale. Hot air flows toward the poles, and cold air moves toward the equator. At the Equator, winds are diverted north and south, leaving a generally windless band called the doldrums. Prevailing winds, global winds that blow in fairly constant patterns. We can predict weather because of atmospheric patterns like the prevailing winds. El Niño - A periodic change in the pattern of mid-Pacific ocean currents and water temperatures, leading to worldwide climate alterations. It has become more frequent and may be linked to global warming. Although controversy exists over the causes of global warming, scientists agree that air temperatures are increasing. Some scientists believe that this warming is part of the earth’s natural warming and cooling cycles. Other scientists argue that global temperature increases are caused by the greenhouse effect. This means that humans may also be a factor of climate. Latitude plays a big role in climate. Geographers divide the earth into three general zones of latitude: low or tropical, middle or temperate, and high or polar. The earth’s two temperate zones lie at the middle latitudes, between the tropics and the polar regions. Within the temperate zones, climates can vary greatly, ranging from relatively hot to relatively cold. Another factor in determining a region’s climate is altitude (distance above sea level). As altitude increases, the air temperature drops about 3.5°F for every 1,000 feet of height. Landforms also affect climate. This is especially true of mountain areas. As winds move up the side of a mountain, they cool and release moisture as rain or snow, on the windward side of the mountain. The winds that reach the other side of the mountain are dry and become warmer as they descend. The drier side is known as the leeward side. Orographic precipitation falls on the windward side of hills or mountains that block moist air and force it upward. Climate World Climate Patterns The two most significant factors in defining different climates are temperature and precipitation. The most common method of describing climate patterns uses latitude to help define the climate. There are five general climate regions: tropical, dry, midlatitude, high latitude, and highland. Tropical Wet – (ex. Hawaii) little variation, always hot, rain is spread out evenly Tropical Wet & Dry – (ex. Serengeti) rainy season in the summer & dry season in the winter Steppe/Semiarid – (ex. Great Plains) receives little moisture, found around desert or interior of continents. Desert – (ex. Sahara Desert) receive less than 10 inches of rain per year Mediterranean – (ex. S. California) summers dry & hot, winters cool & rainy Marine West Coast – (ex Seattle) cloudy, foggy, & damp, rain is spread out evenly during the year, found near the coast. Humid Subtropical – (ex Houston) long hot & humid summers, cool & mild winters, often subject to hurricanes in the late summer and fall. Humid Continental – (ex New England) experiences all four seasons, great variety in precipitation & temperature Subarctic – (ex. Anchorage) long & cold winters, cool & short summers, evergreen forest cover the land Tundra – (N. Russia) flat & treeless, cold temperatures, little precipitation Ice Cap – (ex. Antarctica) snow ice & permanently freezing temperatures, Often called polar desert receives less than 10 inches of precipitation per year Highlands – (ex Himalayas) varies with latitude, elevation, topography and continental location Vegetation patterns are based on large-scale ecosystems. Forest regions are categorized by the types of trees they support. The trees may be broadleaf or needle leaf. Broadleaf trees are also called Deciduous. The rain forest is covered with a heavy concentration of broadleaf trees. In the Deciduous region, leaves fall at least once during the year. Sometimes deciduous trees are mixed with needle leaf trees. Needle leaf trees also called Coniferous trees because they bear cones. Grasslands are mostly flat regions dotted with a few trees. They are called by different names around the world. The plants that live in the desert and tundra climate regions are specially adapted to tolerate the dry or cold conditions. The impact of humans on soil and vegetation is immense. Human beings have adapted to the land by changing their lifestyles. Sometimes they change the land to meet their needs. This includes building dams or irrigation systems, planting food crops, or slashing and burning the vegetation. Human Environment Interaction III. Human Environment Interaction A. How do we use our Planet? B. How have we altered our planet? C. How have we adapted to our Planet? How do we use our Planet? The Solar System consists of the sun and eight known planets, as well as other celestial bodies that orbit the sun. The celestial bodies include moons, asteroids, and dwarf planets. The Earth is the third planet from the sun. Only earth has liquid water and can support a variety of life. All life and material on Earth exists in one of our planet’s four Geospheres. Atmosphere – layer of gases surrounding the earth. Lithosphere – the solid rock portion of the earth’s surface. Some of the Lithosphere is below water and forms the ocean floor. The huge landmasses above water on the earth are called continents. There are seven total. Hydrosphere – the water elements on earth. Oceans, seas, rivers, lakes, and the water in the atmosphere make up the Hydrosphere. Ecosphere – the part of the earth where plants and animals live. Humans use the Earth resources for survival. One unique resource that is key to survival is water. The ocean is an interconnected body of salt water that covers about 71 percent of our planet. The four oceans are the Atlantic, Pacific, Indian, and the Arctic Ocean. The salty water of the ocean circulates through three basic motions: currents, waves, and tides. The motion of the ocean helps distribute heat on the planet. Winds blow over the ocean and are heated or cooled by the water. When the winds blow across the land, they change the temperature of the air over the land. The hydrologic cycle is the continuous circulation of water between the atmosphere, the oceans, and the earth. Water evaporates into the atmosphere. The water in the atmosphere exists as vapor. When the vapor cools, it condenses. Water vapor in the atmosphere can become precipitation, falling water droplets, in the form of rain, sleet, snow, or hail. 97% of the worlds water is found in oceans. This water is too salty for drinking and farming. 2% of the world’s water supply is fresh but frozen in glaciers and ice caps. This leaves only another 0.5% is under the earth’s surface (Groundwater). Aquifers are underground layers of porous rock that is saturated with water and acts like and underground stream. Less than 1% in the world’s water is found rivers, lakes, and streams. Even thought very little water is found here they are very important to survival, agriculture, and transportation. How do we alter our Planet? Humans must use their environment to survive. Altering the environment has made survival easier for human. Humans are capable of flattening mountains, creating islands, and changing the direction of rivers. Not all human alteration have been positive. We have caused deforestation, over farmed the land, and polluted the environment. How do we adapt to our Planet? Humans cannot change everything about the Earth’s Landscape and Climate and must adapt to the conditions. The Earth is constantly changing and there are many forces humans are unable to control like climate the changes caused by tectonic movement. An Earthquake is the violent movement of the earth produced when tectonic plates grind or slip past each other. Damages can be great at the Epicenter (The location on the earth’s surface directly above where an earthquake originates) and earthquakes can trigger of disasters like Tsunami (A giant wave in the ocean caused by an earthquake). We cannot control or prevent an earth quake but we can monitor tectonic activity and prepare. Seismograph – A device that measures the size of waves created by an earthquake. Richter Scale – Scale that uses seismograph results to determine the force of an earthquake. Humans are unable to control extreme forms of weather but they can adapt to them. Think of ways in which humans adapt to the following climatic conditions. Droughts Blizzards Tropical Storms Are humans using, altering or adapting to their environment in these pictures?