It has become commonly known in recent years that the surface of the earth is floating on a giant pool of liquid hot magma. This is explained by a concept known as plate tectonics.
Plate tectonics states that the earth is made up of several different and seperate plates. These plates are floating on molten rock far under the ground. This concept explains things such as earthquakes, volcanoes, rifts in the earth, and other motion of the earth's surface.
The outermost part of the Earth's interior is made up of two layers: above is the lithosphere, comprising the crust and the rigid uppermost part of the mantle. Below the lithosphere lies the asthenosphere. Although solid, the asthenosphere has relatively low viscosity and shear strength and can flow like a liquid on geological time scales. The deeper mantle below the asthenosphere is more rigid again. This is, however, due not to cooler temperatures but to high pressure (http://en.wikipedia.org/wiki/Plate_tectonics).
The tectonic plates of the lithosphere float on the viscous rock of the asthenosphere. Moving plates can cause occurances felt by humans on the earth's surface in one of three ways: convergence, divergence, and transformation. These are the actions that cause earthquakes, volcanoes, and other such occurances.
Transformation is the lateral sliding of two plates past each other. When the plates get "caught" on each other, they build up kinetic energy. When this energy is released, it causes earthquakes. An example of this is the San Andreas Fault, on the western coast of North America.
Divergence is the process of tectonic plates moving apart from each other. When this happens, magma from under the earth's crust forces itself up under immense pressure, creating a "hotspot". Divergent movement can also cause the formation of underwater rifts, such as the Mid-Atlantic Ridge.
Convergence is the opposite of divergence. It is the colliding of two plates together. When the two plates collide, one is forced down and the other is forced up creating mountains or volcanoes. An example of convergence is the Cascade Mountain Range in North America (http://en.wikipedia.org/wiki/Plate_tectonics).
The three types of volcanoes that are formed from plate shifting are shield volcanoes, stratovolcanoes, and cinder cones.
Shield volcanoes are fromed from divergence forcing lava up and spreading out to form a wide, flat volcano. Stratovolcanoes are formed by convergence making a mountain come up and forcing lava to flow out. Cinder cones are formed from volcanoes shooting out ashes and cinder, which builds up around the mouth of the volcano.
Thursday, March 8, 2007
exam question 5 the greenhouse effect
The greenhouse effect is a natural occurance that has been happening for ages. The greenhouse effect is the process in which the emission of infrared radiation by an atmosphere warms a planet's surface. (http://en.wikipedia.org/wiki/Greenhouse_effect) This means that as the suns rays hit the earth and reflect back, heading toward space, gases in the atmosphere help to hold some of the suns heat close to the earth. Without the greenhouse effect, the earth would be significantly cooler (by as much as 30°C!). (http://en.wikipedia.org/wiki/Greenhouse_effect)
In recent years, people have been becoming more and more concerned about the increase in global temperature. This is due to a factor known as global warming. Global warming is the process by which human activity causes more than adequate amounts of greenhouse gases (mainly CO2) to be released into the atmosphere. Because of this, more heat from the sun is being retained next to the earth causing increased global temperatures.
Since the year 1860, the average earth surface temperature has increased by about 1°C. If some sort of actions are not taken soon, then by the year 2100 A.D. the average global temperature could be increased by as much as 1°C more!
Such drastic changes in global temperature could completely throw off many of the worlds ecosystems. Increased temperature would cause increased evaporation of many of the earth's bodies of water. This would lead to the environment of many seafaring animals to be destroyed. Increased temperatures would also cause increased algae growth (algal bloom) which would further harm the marine wildlife.
It is my belief that some sort of action must be taken to reduce GHG (greenhouse gas) emission and salvage our earth before it is too late. In order to support the core democratic value of common good, people should try to be more environmentally friendly. If we all pitch in and help to cut back on activities harmful to the environment, we will be able to preserve our world for future generations.
In recent years, people have been becoming more and more concerned about the increase in global temperature. This is due to a factor known as global warming. Global warming is the process by which human activity causes more than adequate amounts of greenhouse gases (mainly CO2) to be released into the atmosphere. Because of this, more heat from the sun is being retained next to the earth causing increased global temperatures.
Since the year 1860, the average earth surface temperature has increased by about 1°C. If some sort of actions are not taken soon, then by the year 2100 A.D. the average global temperature could be increased by as much as 1°C more!
Such drastic changes in global temperature could completely throw off many of the worlds ecosystems. Increased temperature would cause increased evaporation of many of the earth's bodies of water. This would lead to the environment of many seafaring animals to be destroyed. Increased temperatures would also cause increased algae growth (algal bloom) which would further harm the marine wildlife.
It is my belief that some sort of action must be taken to reduce GHG (greenhouse gas) emission and salvage our earth before it is too late. In order to support the core democratic value of common good, people should try to be more environmentally friendly. If we all pitch in and help to cut back on activities harmful to the environment, we will be able to preserve our world for future generations.
Tuesday, March 6, 2007
exam question 3 renewable/nonrenewable resources
Renewable resources are resources that can either be produced quickly and in infinite quantities, or never runs out. These are things such as the sun, wind, and biomass. Nonrenewable resources are found in the earth and either take millions of years to regenerate, or can never be recovered.
Throughout different earth systems, energy sources can change to different forms. For example, hydro energy is based on water, which can be in different states. Some sources of energy such as this can only be used in one form.
Humans have many choices in which kinds of energy they can use. Renewable resources are usually more environmentally friendly, but can cost a lot to harvest. Nonrenewable resources are more easily obtained, but can be harmful to the environment. Eventually all the nonrenewable resources will be used up and people will have to look elsewhere (renewable resources) for energy.
Using nonrenewable resources such as coal, petroleum, and other such fossil fuels should not be used in such excess as it is. These sources of energy are easy to obtain, but are harmful to the environment. The only good thing about fossil fuels is that they are relatively cheap. I believe that the use of fossil fuels should be reduced and we should shift more towards the use of more efficient and environmentally safe sources of energy
I think that the two most logical kinds of energy to use would be solar energy and wind energy.
Solar energy is obtained by converting the suns rays into energy through the use of photovoltaic cells. These capture light from the sun and convert it into energy that can be used for heating, cooking, and electricity. Solar energy can also be stored and used at a later time (at night). (http://en.wikipedia.org/wiki/Solar_power) This would be a very clean, cheap, and environmentally friendly way to produce energy. The only costly part would be to build solar panels large enough to produce energy for a significant number of people, but after that expense was taken care of, we would have a great source of energy.
Another good source of energy would be wind energy. It is very clean and can produce much energy in the right conditions. However, wind energy would only be logocal to use in windy areas. The initail cost of building turbines and generators to harvest wind energy could be quite expensive, but if they were built in the right areas, the turbines would be very beneficial and produce much energy. (http://en.wikipedia.org/wiki/Wind_energy) However, I still believe that solar energy will be the main energy of the future.
Throughout different earth systems, energy sources can change to different forms. For example, hydro energy is based on water, which can be in different states. Some sources of energy such as this can only be used in one form.
Humans have many choices in which kinds of energy they can use. Renewable resources are usually more environmentally friendly, but can cost a lot to harvest. Nonrenewable resources are more easily obtained, but can be harmful to the environment. Eventually all the nonrenewable resources will be used up and people will have to look elsewhere (renewable resources) for energy.
Using nonrenewable resources such as coal, petroleum, and other such fossil fuels should not be used in such excess as it is. These sources of energy are easy to obtain, but are harmful to the environment. The only good thing about fossil fuels is that they are relatively cheap. I believe that the use of fossil fuels should be reduced and we should shift more towards the use of more efficient and environmentally safe sources of energy
I think that the two most logical kinds of energy to use would be solar energy and wind energy.
Solar energy is obtained by converting the suns rays into energy through the use of photovoltaic cells. These capture light from the sun and convert it into energy that can be used for heating, cooking, and electricity. Solar energy can also be stored and used at a later time (at night). (http://en.wikipedia.org/wiki/Solar_power) This would be a very clean, cheap, and environmentally friendly way to produce energy. The only costly part would be to build solar panels large enough to produce energy for a significant number of people, but after that expense was taken care of, we would have a great source of energy.
Another good source of energy would be wind energy. It is very clean and can produce much energy in the right conditions. However, wind energy would only be logocal to use in windy areas. The initail cost of building turbines and generators to harvest wind energy could be quite expensive, but if they were built in the right areas, the turbines would be very beneficial and produce much energy. (http://en.wikipedia.org/wiki/Wind_energy) However, I still believe that solar energy will be the main energy of the future.
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