A Living Planet. The Earth Inside and Out

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1 A Living Planet The Earth Inside and Out

2 Planet Earth Earth s Rotation, Revolution, and Tilt Most of Earth s energy comes from the Sun, which we call solar energy. Imagine that the Earth has an imaginary rod running through it from the North Pole to the South Pole. The rod represents the Earth s axis, and the planet spins around it:. One complete spin of Earth on its axis is one rotation, and takes 24 hours. Solar energy strikes only the half of Earth facing the Sun. The Earth s rotation allows the entire planet s surface to receive the warming effects of daylight and the cooling effects of darkness. In addition to rotating on its axis, Earth revolves around the Sun. It makes an elliptical orbit, or revolution every 365 ¼ days.

3 As Earth revolves around the Sun, its axis points toward the same spot in the sky, the North Star. Earth s axis is tilted at 23 1/2 from the perpendicular, or 90 to the plane of its orbit. This tilt affects the amount of solar energy that different places receive during the year. The Earth-Sun Relationship Areas around the Equator receive a lot of solar energy all year. We call these warm low-latitude areas near the equator tropics. Twice during the year, Earth s poles tilt toward or away from the Sun more than at any other time. The point at which the Earth s greatest angle toward or away from the Sun is called a solstice During the December (12/21) solstice the Sun s rays strike the Earth in the Southern Hemisphere along a parallel 23 ½ south of the Equator. This is the Tropic of Capricorn. The summer solstice occurs on 6/21. The parallel beyond which no sunlight shines on this day is known as the Arctic Circle. The parallel at 23 ½ south

4 latitude is the Tropic of Cancer. Seasons are the times of greater and lesser heat. Seasons are a result of Earth s tilt and revolution. An equinox occurs twice each year. It is one of two times each year when the position of the noon sun is overhead at the Equator. Equinox means equal night, and there are an equal number of day and night hours. The spring equinox occurs on March 20 and the fall equinox occurs on September 22.

5 Weather The Sun plays the major role in Earth s weather patterns. Weather is the condition of the atmosphere at a given time and place. Climate is weather conditions in a geographic region over a long time.

6 The Water Cycle The water cycle is the movement of all the water on the earth s surface. Without water vapor, there would be no clouds, rain or storms. When precipitation fills in cracks and spaces under the surface, is the water table (the level at which all spaces are

7 Plate Tectonics Huge convection currents carry heat from the core through the mantle to the crust. Liquid rock inside Earth is called magma, while lava is outside of Earth. Convection is a circular movement caused when a material is heated, expands and rises, then cools and falls. These currents drive plate tectonics

8 If you study a world map, you ll notice that some of the continents fit together. The first person to notice this was Francis Bacon in 1620, then in the early 1900s, scientists found rocks in Africa that matched rocks in South America. This is part of theory known as plate tectonics, which explains how forces within the

9 The plates can be compared to the cracked shell of a hard-boiled egg. The plates slowly move across the upper mantle, usually less than an inch per year. This process is called continental drift. Along the plate boundaries, the crust is subject to stresses that lead to melting, bending, and breaking. Earthquakes take place when tectonic forces cause masses of rock inside the crust to break, and are common near plate boundaries Earthquake video: /simulations/1906/

10 There are 14 major plates, and the Pacific Plate is the largest. Plate divergence is when the midocean ridge, or underwater mountains, spread. When this happens on the oceanic crust, a spreading ridge occurs, and when it happens on the continental crust, a rift valley or rift zone develops: Lake Baikal, and the Red Sea and Rift Valley in Eastern Africa are all a result of this.

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12 Plate convergence is when two plates move toward each other and collide, creating mountains: The Himalayas are being created with this force. A subduction zone occurs when oceanic crust meets continental crust, and the Denser oceanic crust descends below the lighter continental crust. The Wasatch Fault is an example of this process. A lateral plate boundary is when plates slide past each other. The San Andreas Fault in California is an example of this movement.

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14 A seismograph measure the size of the waves that the earthquake creates, telling us that an earthquake happened. The focus is the point within the earth s crust where an earthquake occurs, Alaska (1964) 9.2, Chile (1960) while the epicenter is the point on the surface directly above where an earthquake takes place. The Richter scale determines the magnitude of an earthquake on a progressive scale of The largest earthquakes ever recorded include: Chile (2010) 8.8, Kamchatka (1952) 9.0, Japan (2011) 9.0, Sumatra (2004) 9.3, The Ring of Fire is the area around the Pacific Plate. Ninety-five of all earthquakes and volcanoes occupy this area. Eight major plates meet at the Ring of Fire:

15 Each magnitude is 10 times greater than the previous. A 2 is 10 times greater than a 1, but a 3 is 100 times greater than a one. That means that a 7 is 1 million times greater than a 6.

16 A tsunami is a series of long period waves caused by earthquakes or volcanic eruptions. The 1960 earthquake in Chile caused a tsunami in Japan that killed 225,000. A tsunami accompanied the Sumatra 2004 earthquake, leaving 230,000 people dead across 13 different countries. It was the fifth deadliest natural disaster in recorded history. Over 45,000 of the dead were never found Tsunami: Japan Tsunami:

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18 Landforms Landforms are features of the Earth s surface that are part of the terrain. They are formed by processes that occur inside and outside of the earth.

19 Prevailing winds in the upper atmosphere that miles above the ground are jet streams. These high-speed westerly winds can reach more than 300 miles per hour. They travel in the direction of weather in the northern hemisphere, which is west to east. Hurricanes are low pressure and produce high winds and heavy rains (also called cyclones or typhoons). They are identified by the eye in the storm: (Hurricane Katrina) Hurricane video:

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21 Tornadoes are compact, powerful whirlwinds powered by differences in wind, moisture and temperature. They have wind speeds of mph, and can be up to two miles wide. Although tornadoes occur in India, Bangladesh and other regions, they are most intense and devastating in the United States. Tornadoes are most frequent in the afternoon and evening, after the daily buildup of heat powers a violent supercell thunderstorm that can produce a tornado.

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24 A funnel cloud rotates in the sky, but is not on the ground: A waterspout is a tornado over water: