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Understanding the Earth's place in the universe, its layers, and its atmosphere is essential to learning about geography because it provides the foundation for how our planet functions while furthering our understanding of geography. Specifically, a strong grasp of these concepts helps us appreciate Earth's dynamic systems and the interconnectedness of land, air, and life.
The Earth is a planet in the Solar System and the third planet from the Sun. Its structure and surfaces makes it the only known planet to support life, and is the birthplace of humankind.
The Earth rotates on its axis about 1,000 mph. This takes 24 hours and gives us our days.
The Earth revolves around the sun about 67,000 mph. It takes about 365.25 days to do this. This gives us our years.
The Sun, Earth, and the entire solar system also are in motion, orbiting the center of the Milky Way Galaxy at a blazing 140 miles a second (over 500,000 mph).
Planet Earth
Our home, the Earth, is the fifth largest planet in our solar system, has a mean distance from the Sun of about 93 million miles (150 million km) and it takes 365.25 days to complete one orbit or revolution around the Sun.
How does this give us our "Leap Years?"
The Earth's shape is an oblate spheroid, meaning it is slightly flattened at the poles and bulging at the equator. This shape is due to the Earth's rotation (about 1,000 miles per hour), the centrifugal force it generates, and the moon's gravitational pull on the oceans.
Structure of the Earth
The Earth's structure is divided into four distinct layers: the inner core, outer core, mantle, and crust. The inner core is a solid sphere of iron and nickel and is the hottest part of the Earth, with temperatures estimated to reach over 7,200°F (4,000°C). The outer core is a liquid layer of iron and nickel and is responsible for generating the Earth's magnetic field. The Earth's lithosphere (outer layer) is made up of the mantle and and crust. The mantle is a thick layer of solid rock, and the crust is the thin, solid outermost layer that makes up the Earth's surface.
Surface of the Earth
Plate Tectonics
The Earth is a planet with a diverse physical geography. It has a solid surface composed of a series of interconnected tectonic plates that move and interact with each other, giving rise to geological phenomena such as earthquakes, volcanic eruptions, and mountain formation.
Continents
Earth's surface is about 71% water and 29% land. The surface of the Earth is divided into several large land masses, known as continents, and several smaller islands. The seven continents are Africa, Antarctica, Asia, Australia, Europe, North America, and South America. The continents are surrounded by vast oceanic bodies of water, including the 5 oceans: Atlantic, Pacific, and Indian, Arctic, and the Great Southern Oceans.
Landforms
The Earth's topography is characterized by a range of landforms, including plains, plateaus, valleys, deserts, mountains, and hill regions. Some of the most notable mountain ranges include the Andes in South America, the Rockies in North America, the Alps in Europe, and the Himalayas in Asia.
Bodies of Water, Atmosphere, and Climates
The Earth's surface is also dotted with bodies of fresh water, including rivers, lakes, and wetlands, and its atmosphere is composed of a mixture of gases, including nitrogen, oxygen, and carbon dioxide. The Earth's climate is influenced by a range of factors, including latitude, altitude, ocean currents, and atmospheric circulation patterns, giving rise to a range of climates, from arctic tundras to tropical rainforests.
Earth’s atmosphere has five major and several secondary layers. From lowest to highest, the major layers are the troposphere, stratosphere, mesosphere, thermosphere and exosphere.
The troposphere is the densest atmospheric layer, compressed by the weight of the rest of the atmosphere above it. Most of Earth’s weather happens here, and almost all clouds that are generated by weather are found here, with the exception of cumulonimbus thunder clouds, whose tops can rise into the lowest parts of the neighboring stratosphere.
The stratosphere is perhaps best known as home to Earth’s ozone layer, which protects us from the Sun’s harmful ultraviolet radiation. Because of that UV radiation, the higher up you go into the stratosphere, the warmer temperatures become.
The top of the mesosphere layer is the coldest place found within the Earth system, with an average temperature of about minus 85 degrees Celsius (minus 120 degrees Fahrenheit). Most meteors burn up in this atmospheric layer.
The aurora borealis and aurora australis are sometimes seen in the thermosphere and the International Space Station orbits the Earth here.
The exosphere is the highest layer of Earth’s atmosphere and, at its top, merges with the solar wind. Most Earth satellites orbit in the exosphere.
While there’s really no clear boundary between where Earth’s atmosphere ends and outer space begins, most scientists use a delineation known as the Karman line, located 100 kilometers (62 miles) above Earth’s surface to denote the transition point which is located in the thermosphere.
Conclusion
Overall, the Earth's physical geography is complex and dynamic, shaped by geological processes, climate patterns, and biotic interactions, and continues to evolve over time. Understanding these concepts helps greatly in our studies of geography.
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