Geography researchs

Earth's atmosphere. Layers. Mid-Ocean Ridge. Abyssal plain. Sea movements

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  • Idioma: inglés
  • País: Chile Chile
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Social Studies Geography Research

1. Explain the Earth's atmosphere. Name and draw the 5 layers. Describe them.

The atmosphere is the screen of the Earth. This air, a combination of gases that we call Atmosphere, is made up of more than a 99% of Nitrogen and Oxygen. Thanks to these gases we are able to live and breathe, and it stays together to Earth by the force of Gravity. Another important compounds, but that appear in a small proportion are Carbon Dioxide (0, 03%), water vapor (variable), and Ozone (variable).

Without the Atmosphere, life on Earth would be much more different than now. Without the existence of this shield, that has lots of layers, which absorbs and repels loads of dangerous sunbeams, all the planet would be a complete desert (because of radiation) in the day; and a frozen area in the night (because the heat escapes to space).

Atmosphere absorbs about the 15% of the radiation that comes from the cosmos. This is very important, because without the help of the atmosphere to take away the radiation from Earth, we could have great danger.

The Atmosphere is made up of 5 layers, and they are:

-Troposphere: The lowest but the most important layer of the Atmosphere extending from the surface of the earth to about 7 miles is the Troposphere. The temperature here decreases with the increase of altitude. This layer contains 75% of all the air found in our atmosphere and most of the water vapor. The air in this layer moves in a vertical direction (up and down). Thus with this vertical movement of air combined with the water vapor the stage is set for the phenomenon called weather.

-Stratosphere: Below the Mesosphere extending from about 7 miles above the Earth's surface to about 30 miles is the Stratosphere. The temperature remains about the same in the lower part of this layer but then starts to rise. This is where the Ozone layer is found about 25 to 50 miles above the surface of Earth. The ozone layer is warm because it absorbs the ultraviolet radiation from the Sun. The air movement here is in the horizontal direction with little or no water vapor.

-Mesosphere: Below the Thermosphere extending from 30 miles to 50 miles is the Mesosphere. The temperatures decrease with altitude. Making this the coldest part of the atmosphere. Here the temperatures starting in the lower part of the Mesosphere range from 30 degrees to -90 degrees Farenheight in the upper layer of the Mesosphere.

-Thermosphere: The upper layer from Mesosphere of the entire Atmosphere extending for 50 miles up above the Earth is the Thermosphere. This is the warmest layer with temperatures rising to about 3,000 degrees Farenheight because the Nitrogen and Oxygen atoms absorb the unshielded energy from the Sun.

-Exosphere: The Atmosphere merges into space in the extremely thin Exosphere. This is the upper limit of our Atmosphere. It almost doesn't have its own gases, but some molecules escaping from gravity cross this layer and disappear in the Infinite.

2. How were the continents made? Name the Earth's plates and draw them.

560 millions of years ago, continents were like deserts, something that we cannot really understand. The first earth masses are identifiable; some of them like Great Britain, Scandinavia, Siberia and proportions of Australia and a big part of North America, where, maybe under water (Seas, oceans).

Just one continent, that was called Gondwanaland, grouped together South America, Africa, the south of Europe, the Antarctic and Oceania. In a corner there was India, subcontinent that after millions of years would be impelled (driven) to the Asiatic continent.

Asia was separated from the group of the South, the same than the north of Europe (Baltica), and North America (Laurentia) and two continents divided by the Yapetus or Protoatlantic Ocean (probably what is now known as the Atlantic Ocean, which divides the now known as Great Britain). Scotland and Ireland almost were together with North America, while Newfoundland (Terranova) was very closer to Europe. The scientist Alfred Wegener named “Laurasia” this group of lands. He considered that Laurasia and Gondwanaland formed at the time the Pangaea, and that this broke little by little and separated to form the actual continents.

Approximately 410-440 million years ago the Yapetus Ocean “shut off”. About 500 million years ago the land masses in the Southern Hemisphere were changing their shape and position (based on paleomagnetic data) as Baltica and land fragments of Gondwana were shifting towards Laurasia. The convergence of these continental elements that took place 400 million years ago gave birth to the Ancient Red Continent. In the Paleozoic era, Gondwanaland drifting north collided with it thus forming the Pangaea nucleus.

The Earth's surface is broken into seven large and many small moving plates. These plates, move relative to one another an average of a few inches a year. When an oceanic plate collides with a continental plate, the oceanic plate tips down and slides beneath the continental plate forming a deep ocean trench (long, narrow or deep). An example of this type of movement, called subduction, occurs at the boundary between the oceanic Nazca Plate and the continental South American Plate. Where continental plates collide, they form major mountain systems such as the Himalayas. The more important Plates tectonicts are:

-Pacific Plate

-Australian Plate

-Nazca Plate

-South American Plate

-African Plate

-Eurasian Plate

-Antartic Plate

There are also another smaller plates that are not too important, but they are Plate tectonicts, too: Caribbean Plate, Arabian Plate, Cocos Plate, Juan de Fuca Plate, Philippine Plate and Scotia Plate.

3. About the Ocean floor. What are the continental Shelf, the continental edge, and the Abyssal plain? Describe them, and draw them.

The bottom of the Ocean, repeats, but in an opposite way, the terrestrial relief with plains, plateaus and mountains. This way, submerging, we can find:

-Continental shelf: It's a flat zone that represents a continuation of the continents under water and it doesn't reach 200 meters of depth.

-Continental edge: Abrupt falling of depth, which reaches the 2,000 meters. It's a deep difference produced between the continental platform and the marine depths.

-Abyssal Plain: Belongs to the bottom of the ocean, with types of submarines valleys that are interrupted by deep graves (with depths that reach between 6,000 and 11,000 meters) or crossed by real submarines mountain ranges, called “dorsales”, and its high summits emerge to the surface in shape of islands in the middle of the ocean. A typical case is the Easter Island.

4. What is the Mid-Ocean ridge?

The driving force behind the process of plate tectonics is heat generated deep inside the Earth's center by radioactive decay. This heat reaches the surface mainly along the Mid-Ocean Ridge. One of the Earth's most dramatic topographical features, the Mid-Ocean Ridge is a continuous range of undersea mountains more than 12,000 feet high and 1,200 miles wide winding through 40,000 miles of the world's oceans. It is here, at Mid-Ocean Ridges, that new sea-floor crust is produced and much of the Earth's internal heat is released.

At Mid-Ocean Ridges, two plates are pulling apart from each other as hot magma (liquid rock) emerges from the mantle and oozes (escapes) forth as lava to fill the crack continuously created by plate separation. The lava cools and attaches itself to the trailing edge of each plate, forming new ocean floor crust in a process commonly known as sea-floor spreading.

All plates have a so-called `leading edge' and `trailing edge'. The leading edge is simply the front of the plate, that edge which `leads' the plate in the direction that it's moving. The trailing edge is the back end of the plate. At Mid-Ocean Ridges new crust is added to the trailing edge of each of the two separating plates. From here, the further sea-floor crust is from the mid-ocean ridge.

5. What are the sea movements? Describe them and stick pictures of them.

Water of oceans and seas are always moving, these movements make the sea be more adaptive to shelter sea life. The most important movements are:

-Waves: crinkle movements of water, produced by the wind that blows above the sea surface. When it cracks in the coast (the beach), the water of waves splashes everywhere, ventilating itself and wetting the sand and rocks, facilitating the life of the habitants (animals, etc.) of the coast.

-Tides: ascents and descents of the sea level are produced by the approach of its water to the coast. The ascents, called high tides, are produced two times per day; the same than low tides or descents. The tides are done by the attraction force that discharges the Sun and Moon onto the Earth. On the other hand, if the Sun and Moon tend to line in a certain point, the gravity attraction of Sun combines with the gravity attraction of the Moon and in those moments the most high tides and low tides are produced.

-Marine currents: displacement of great masses of water through long distances, produced by the force of regular and constant winds in a certain direction (Trade winds) and the rotation of the Earth. The water of these currents keeps their own salinity, temperature and color. Its principal characteristic is the temperature, and they called them warm or cold currents. Is very important for us the cold current of Humboldt, which washes the Chilean coasts. The cold current of Humboldt is, a blessing for our country, since it transports numerous nutrients and it is rich in oxygen, what allows the development of a varied and rich animal life that provides big wealth for the country. An example of a warm current is the one located in the Mexican Gulf. The marine currents are very important: they permit the movement of living things on water and that the tropical seas don't overheat nor the polar seas under cool.

6. Draw a world map and show the main sea currents. Explain their effects.

The main sea currents are:

-Gulf current: the tropical waters follow this principal route toward the north and later toward the east, in the northern Atlantic. It's a warm current.

-Equatorial Counter-current: The Trade winds push the water toward the west of the oceans; the Equatorial counter-current flows toward the east and it restores the balance. It's a warm current.

-“Labrador” current: Icebergs and cold waters that get off the sea Baffin enter in contact with the Gulf current in front of the coast of Newfoundland and they produce an area of fog. It's a cold current.

-“Benguela” current: it drives water toward the north and toward the west with direction to the half ocean. When making it, it takes nutrients that feed enormous quantities of fish. It's a cold current.

-Humboldt current: A cold current that takes nutrients to the surface, where the fish are plentiful. More less every 10 years, complex climatic conditions strengthen the Equatorial Counter-current that flows toward the east. The Humboldt current suffers changes. The nutrients stop emerging and the fish die. As that happens in the Christmas time, the fishermen have given the name of "El Niño" to this phenomenon. (In English they call it “Christ Child”)

-Antarctic current: It's the biggest one, impelled by the western winds. It moves about 800 meters per hour. It's a cold current.

7. Explain the climate zones. Describe them.

The 90% of the layers that make up the Atmosphere are found in the lower layer from the Earth. This layer is called Troposphere and its density is approximately from 6 to 8 kilometers in the poles, 17 kilometers from the Equator.

Is in this layer that happen all the atmospheric phenomenon that determine the climate changes. Looking the different types of climates on Earth, they found 3 typical climate zones:

-Warm zones: Located at the north and south from the Equator, very near it, where the Sunbeams arrive with intensity, that's why the temperature is very high during all the year. It, too, rains a lot and the air humidity is big. In the warm zones, the vegetation is varied, and we can find jungles that are impossible to go into. The fauna is varied, too and most of the animals have a nocturne life, so they can avoid the suffocating sun.

-Template zones: Located in the northern and southern hemisphere. When it's winter, the sunbeams don't warm too much, but there's not an extreme cold. In summer, sunbeams are more dense, but it's not suffocating. There's a great variety of plants, that's why there are lots of animals, too. These is the favorite zone in which men likes to live. They can develop the agriculture, animals raising, and they can build their house of varied materials: clay, bricks, wood, etc..

-Cold zones: They are located near the polar circles. In this zone, the vegetation is very scarce, because of the lack of sun. The animals that live in these areas are adapted to the cold. For example, the polar bears are covered with a thick skin that shelters them. The fish, abundant in the cold seas, is the food of many animals. In these areas the man's life is very difficult, for that reason it is not so populated. However, there is a town that has lived for many years in the North Pole: the Eskimos that have survived the cold.

8. Conclusion.

I think that the climate is changing nowadays because of the overheat of Earth. There are specifics natural phenomenon that modify or alter the climate changes, and that's natural, but there are other things that can alter the climate, and possibly finish with life. Why? In the last decades, the atmosphere has been very misuse, chemical compounds have been integrated but in so high concentrations, that they remain in it, elevating the temperature of the atmosphere. The climate changes, the sunbeams, as the atmosphere is so misused, penetrate on Earth. But the sunbeams are not all good, there are sunbeams that are bad for humanity and produce sicknesses like cancer, burns, scorches to men. They can also burn plants, vegetation and they are so powerful that they can decolorize tapestries, clothes, wipes, etc. We are exposed to more danger now than we were before, and this is just our own fault. All of this, the concentration of heat on Earth causes the Greenhouse effect, and this phenomenon will contribute to the climatic changes that are presented in the future and they can be more drastic than those happened in the last 100 years.

The main gases of this category are the Carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, ozone and even water vapor. These elements can be natural compounds of the atmosphere, but the problem resides in the high concentration of the same ones that makes impossible to remove them of the atmosphere in a natural way. And they stay there. The ozone layer is so disused, that it can't do its work. The ozone layer used to filter the ultraviolet sunbeams, that were dangerous to animals, plants and humans, but now, as it is not there or at least it's disappearing, the ultraviolet sunbeams arrive to Earth as they are sent by Sun. And that's the dangerous thing.

And, what can we do? I think the only thing that humans can do to help, is stop the contamination of Earth. We have to stop using cars (because they contaminate a lot more than we think), stop using chemical and toxic things, etc. That's the only thing we can do to stop this big problem: the concentration of heat and the changes of climate (hotter ones).