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| − | [[Image:Altocumulus15.jpg|thumb|Altocumulus cloud as seen from the space shuttle. Altocumulus is formed through convective activity.]]
| + | {{honor_header|1|1944|Nature<br>General Conference<br>2001 Edition}} |
| − | [[image:granules2.jpg|thumb|Convection cells on the Sun with North America superimposed]]
| + | ==1. Explain how each of the following is formed:== |
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| | + | ===a. Fog === |
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| | + | ===b. Rain === |
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| | + | ===c. Dew === |
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| | + | ===d. Snow=== |
| | + | ===e. Sleet=== |
| | + | ===f. Hail=== |
| | + | ===g. Frost=== |
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| | + | ==2. Identify either in the sky or from pictures the following types of clouds: cirrus, cumulus, stratus, nimbus. What kind of weather is associated with each.== |
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| | + | ==3. Explain the action of a mercury or spirit thermometer, a mercury barometer, an aneroid barometer, and a rain gauge.== |
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| | + | ==4. Why is it possible to be rainy on one side of the mountain range and dry on the other? Give an illustration for your country or region.== |
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| | + | ===a. Why is it cooler and more moist in the mountains than in the lowlands?=== |
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| | + | ===b. From which direction do rain and clear weather usually come in your locality?=== |
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| | + | ==5. Show with the help of a diagram how the earth's relationship to the sun produces the seasons.== |
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| | + | ==6. What causes lightning and thunder? What different kinds of lightning are there?== |
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| | + | ==7. Show with the help of a diagram what a convection is. What is its relation to winds?== |
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| | + | ==8. Explain how radar, satellites, and computers are used in weather forecasting.== |
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| | + | ==9. Tell how the following can affect our weather:== |
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| | + | ===a. Jet stream=== |
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| | + | ===b. Volcano eruption=== |
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| | + | ==10. Make a drawing showing the water cycle in weather.== |
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| | + | ==11. Make a simple wind vane or rain gauge.== |
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| | + | ==12. Keep a weather chart for one week and record readings at 12-hour intervals. Include the following:== |
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| | + | ===a. Temperature=== |
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| | + | ===b. Moisture (dew, fog, rain, frost, or snow)=== |
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| | + | ===c. Cloud formation=== |
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| | + | ===d. Wind direction=== |
| | + | ==References== |
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| − | A '''convection cell''' is a phenomenon of [[fluid dynamics]] which occurs in situations where there are [[temperature]] differences within a body of [[liquid]] or [[gas]].
| + | [[Category:Adventist Youth Honors Answer Book|{{SUBPAGENAME}}]] |
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| − | Fluids are materials which exhibit the property of [[flow]]. Both gases and liquids have fluid properties, and, in sufficient quantity, even particulate solids such as salt, grain, or gravel show some fluid properties. When a volume of fluid is heated, it expands and becomes less dense, and thus more buoyant than the surrounding fluid. The colder, more dense fluid settles underneath the warmer, less dense fluid and forces it to rise. Such movement is called [[convection]], and the moving body of liquid is referred to as a ''beaver cell''.
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| − | A rising body of fluid typically loses temperature because it encounters a cold surface, because it exchanges heat with colder liquid through direct exchange, or in the example of the earth's [[earth's atmosphere|atmosphere]], because it radiates heat. At some point the fluid becomes more dense than the fluid underneath it, which is still rising. Since it cannot descend through the rising fluid, it moves to one side. At some distance its downward force overcomes the rising force beneath it and the fluid begins to descend. As it descends, it warms again through surface contact, conductivity, or compression, and the cycle repeats itself. (The heating through compression of descending air is what is responsible for such welcome winter phenomena as what is known in Western North America as a [[chinook wind|chinook]] or in the Alps as a [[Wind#Special winds|foehn]].)
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| − | Convection cells can form in any fluid, including the Earth's atmosphere, boiling water or soup (where the cells can be identified by particles they transport, such as grains of rice), the ocean, the surface of the sun, or even a farmer's field, where large rocks have been seen to be forced to the surface over time in a process either analogous to or directly related to convection (the connection is not yet clear).
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| − | The size of convection cells are largely determined by the fluid's properties, and they can even occur when the heating of a fluid is uniform.
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| − | The [[Sun]]'s [[photosphere]] is composed of convection cells called ''[[Granule (solar physics)|granule]]s'', rising columns of superheated (5800 °C) [[Plasma (physics)|plasma]] averaging about 1000 kilometres in diameter. The plasma cools as it rises and descends in the narrow spaces between the granules.
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| − | ==External links==
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| − | * [http://www.solarviews.com/eng/edu/convect.htm Jet Propulsion Lab description of convection cells]
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| − | * [http://www.mountainnature.com/Climate/Chinook.htm Mountainnature.com - Chinook]
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| − | [[Category:Convection]] | |
