Convection Currents Essay Example | Topics and Well Written Essays - 750 words

Convection Currents - Essay Example This is known as a thermal. Figure 1 cloud formation, which may produce a thunderstorm. A cumulonimbus cloud, or "thunderhead," is a particularly dramatic example of a convection cell. Eventually the heated cell is cooled by the surrounding air, begins to fall, and the cycle is repeated. Whereas the Sun's electromagnetic energy is the energy source for atmospheric convection, asthenospheric convection is fueled by radioactive decay in the earth's core. The convective cells form in the asthenosphere, a region of extremely high pressure at a depth of about 60-200 miles where rocks are deformed and become molten by enormous pressures. In the asthenosphere, the molten material rises in a convection current until it hits the bottom of the upper layer of Earth's interior consisting of the crust and the mantle. Here, it can not rise any farther and begins to move horizontally. Figure 2 depicts the movement of the convection cells in the asthenosphere. The red areas are the heated molten material rising from the earth's center and moving toward the surface. As the material reaches the surface it Figure 2 Eventually the material cools and as it does it becomes denser. This material then slowly sinks through the lighter material until it is again heated by the earth's core. It forms a new convection cell and repeats this same process. In both the atmosphere and the asthenosphere material is moved from one region to another. Lower air levels rise to become the upper air, and as the cooler upper air cells fall they become ground level air. Within the Earth, irregular convection cells within the mantle transfer heat from the core to the surface of the planet. This process is the driving force behind both heat transfer and plate tectonics ("The Restless Earth"). The effect of the rising material also forms mountain ranges. This process also transfers energy from one area to another. This transfer of energy can result in violent activity if the transfer happens abruptly. In the atmosphere we see it form high winds and thunderstorms. In the asthenosphere, energy is usually transferred by heating the earth's crust. In other cases, it may result in a volcano or an earthquake. The hydrosphere is also an active medium that is powered by convection. The movement of convection cells is the force behind the ocean currents. Circulation patterns in the oceans are driven by density differences between warmer and colder hydrospheric cells. As the water circulates, material and energy are transferred. The ocean's water is heated by the sun as well as undersea hot air vents. It is cooled by the polar ice caps. Convection is also responsible for the action of the water cycle. As the sun heats the surface water on the earth, it evaporates and becomes water vapor. This warmed vapor rises until it encounters the cooler air at higher altitudes. Here it condenses back into water and returns to earth as precipitation ("The Water Cycle"). Convection takes place anytime there is a mass of gas or liquid on the earth. It causes our weather, winds, and ocean currents. Convection heats our air and creates our mountain ranges. It results

Foundation Seminar Research Paper Example | Topics and Well Written Essays - 2500 words

Foundation Seminar - Research Paper Example is whether conventional forms of regulation, such as protecting and controlling public communication along with the media’s main cultural and social functions, still play an important role despite the transitions undergone by the media system (Oba and Chalm-Onsted, 2005). Broadcasters and media regulators alike must be able to keep up with such changes and effectively work in an environment that will give them opportunities to upgrade their operations and strategies to new heights. Involvement between these two parties is essential to maintain the success of the TV industry in the coming years. Owing to the expansion of cable television, the multichannel environment has expanded into both the developed and underdeveloped countries (ITU, 2000). In short, multichannel media has expanded in many countries, and the cable penetration rate, such as the number of households that have gained access to cable television, has become an indicator for the development of this form of TV channel distribution. The current study aims to address several objectives- first is to ascertain whether establishing a TV channel in the Middle East that will completely cover all occurrences in the Arab world will play an important role during this time, and second is to identify the challenges that may be faced by individuals who attempt to create such a form of TV channel. The reform process that has taken place in the Arab world has been stationary as changes are moving at a slow pace despite the claims of government leaders that they have been placing much effort on this issue (Liebes and Katz, 2007). The younger generation, most especially, has become exposed to the new trends and resources of which most of the leaders who belong to the older generation do not yet understand (Kraidy and Kahlil, 2007). Therefore, the establishment of a new TV channel in the Middle East that will have a complete and uncensored coverage of all that is happening in the Arab world will help all citizens