Difference between revisions of "AY Honors/Weather/Answer Key"

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{{honor_header|1|1944|Nature<br>General Conference<br>2001 Edition}}
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[[Image:Wave cloud.jpg|thumb|320 px|This wave cloud pattern formed off of the [[Île Amsterdam]] in the far southern [[Indian Ocean]], due to orographic lift of an airmass by the island, producing alternating bands of condensed and invisible humidity downwind of the island as the moist air moves in vertical waves and the moisture successively condenses and evaporates.]]
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==1. Explain how each of the following is formed:==
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'''Orographic lift''' occurs when an [[air mass]] is forced from a low [[elevation]] to a higher elevation as it moves over rising terrain.  As the air mass gains [[altitude]] it expands and cools [[Adiabatic cooling|adiabatically]]. This cooler air cannot hold the moisture as well as warm air and this effectively raises the [[relative humidity]] to 100%, creating [[cloud]]s and frequently [[precipitation (meteorology)|precipitation]].
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===a. Fog ===
 
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[[Image:Acadia NP fog 2005-1-18.JPG|thumb|Fog in Acadia National Park]]
 
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Relative humidity is a measure of how much water is in the air compared to how much water ''can'' be in the air.  As the temperature rises, the air can hold more water, and as it drops, it can hold less. When the humidity is 100% and the temperature drops, the air can no longer hold all the water that is in it. Fog is moisture that gets squeezed out of the air when the temperature drops. 
 
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<br style="clear:both">
 
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===b. Rain ===
 
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[[Image:22 Regen ubt.jpeg|thumb|Rain]]
 
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Rain forms when separate drops of water fall to the Earth's surface from clouds
 
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<br style="clear:both">
 
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===c. Dew ===
 
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[[Image:Water drops on spider web.jpg|thumb|Dew on s spider web]]
 
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Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening. As the exposed surface cools by radiating its heat to the sky, atmospheric moisture condenses at a rate greater than that of which it can evaporate, resulting in the formation of water droplets.
 
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<br style="clear:both">
 
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===d. Snow===
 
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[[Image:Biella-Panoramica Zegna-Bielmonte.jpg|thumb|Snow]]
 
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Snow is precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes. Since it is composed of small rough particles it is a granular material. It has an open and therefore soft structure, unless packed by external pressure.
 
  
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Snow is commonly formed when water vapor undergoes deposition high in the atmosphere at a temperature of less than 0°C (32°F). It can also be produced by falling particles of ice fog formed when the humidity in surface air freezes at very low temperatures.
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==Effects of orographic lifting==
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<br style="clear:both">
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===Precipitation===
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===e. Sleet===
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Precipitation induced by orographic lift occurs in [[Rain shadow#Regions of notable rain shadow|many places throughout the world]]. Examples include:
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In Britain and other Commonwealth countries, sleet refers to snow that has partially melted on its fall to the ground, due to surrounding air that is sufficiently warm to partially melt it while falling, but not warm enough to fully melt it into rain. Thus it refers to partially melted droplets, a mixture of snow and rain. It does not tend to form a layer on the ground, unless the ground has a temperature that is below freezing, when it can form a dangerous layer of invisible ice on surfaces known as 'black ice'.  
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* The eastern seaboard of Australia, which faces prevailing easterly winds,
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* The mountains of [[New Zealand]], which faces a prevailing westerly flow, off the [[Tasman Sea]].
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* The southern [[Andes]], which faces a prevailing westerly flow, off the [[Pacific Ocean]].  
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* The [[Northwestern United States]] and [[Canada]] ([[Oregon]], [[Washington]] and [[British Columbia]]) see prevailing westerly flow off the northern [[Pacific Ocean]]. Places on the sea-facing side of coastal mountains see over 100 inches (over 2.5 m) of [[precipitation (meteorology)|precipitation]] per year. These locales are on the side of the [[mountain]]s which are in the path of [[storm]] systems, and therefore receive the moisture which is effectively squeezed from the clouds.
  
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In American usage, sleet is a form of precipitation consisting of tiny frozen raindrops, or ice pellets. This is often mistaken for hail, but forms in a different fashion and is usually (but not always) smaller. This occurs when snow flakes falling through a small layer of warmer air in the atmosphere will begin to melt. They can then refreeze if they pass back into a layer of colder, sub-freezing air closer to the ground, resulting in little balls of ice. These ice balls may bounce when they hit the ground, and do not freeze into a solid mass unless mixed with freezing rain.  
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===Rain shadowing===
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===f. Hail===
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[[Image:New-Mexico-Lenticular.jpg|thumb|200px|right|A lenticular cloud in New Mexico.]]
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[[Image:Hailstorm.jpg|thumb|Hailstorm]]
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[[Image:Orographic lifting of the air - NOAA.jpg|thumb|200px|right|A cap cloud.]]
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Hail forms on condensation nuclei such as dust, insects, or ice crystals, when supercooled water freezes on contact. Hailstones are usually from the size of a pea to the size of a golfball.
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[[Image:Tadrart01.JPG|thumb|200px|right|Wave clouds.]]
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<br style="clear:both">
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[[Image:Koryaksky Volcano.jpg|thumb|200px|right|Koryaksy volcano, Kamchatka, Russia, showing banner clouds streaming to the right from the peaks.]]
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===g. Frost===
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[[Image:chinook19.11.05.JPG|thumb|200px|right|Chinook arch in Calgary, Alberta, November 19, 2005]]
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[[Image:Frost-oliv.JPG|thumb|Frost]]
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[[Image:Mountains from westlands.jpg|thumb|400px|right|A view of the Front Range of the Rockies capped by a foehn wall.]]
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If solid surfaces in contact with the air are chilled below the frost point, then structures of ice grow out from the solid surface. The size of the crystals depends on time and the amount of water vapor available.
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:''Main article: [[Rain shadow]]''
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<br style="clear:both">
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The highest precipitation amounts are found slightly upwind from the prevailing winds at the crests of mountain ranges, where the relief and therefore the upward lifting is greatest. As the air descends the lee side of the mountain, it warms and dries, creating a rain shadow. On the lee side of the mountains, sometimes as little as 15 miles (25 km) away from high precipitation zones, annual [[precipitation (meteorology)|precipitation]] can be as low as 8 inches (200 mm) per year.<ref name="Whiteman">{{cite book|author=Whiteman, C. David|title=Mountain Meteorology: Fundamentals and Applications |publisher=Oxford University Press|year=2000|id=ISBN 0-19-513271-8}}</ref>
  
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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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Areas where this effect is observed include:
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<gallery>
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* The [[Atacama]] Desert in [[Peru]] and [[Chile]].
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Image:Cirrus over Warsaw, June 26, 2005.jpg|Cirrus
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* [[Switzerland]]'s [[Rhône River|Rhone valley]].  
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Image:Cumulus clouds in fair weather.jpeg|Cumulus
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* Areas east of the [[Cascade range]] in the Pacific Northwest ([[Washington]] and [[Oregon]]).
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Image:St1.jpg|Stratus
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* Areas east of the [[Olympic Mountains]] in Washington state.  
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Image:Rolling-thunder-cloud.jpg|Nimbus
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* The [[Hawaii|Hawaiian]] [[island]] of [[Kauai]].
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</gallery>
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* [[California]]'s [[Central Valley]].
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;Cirrus: Cirrus clouds are at the highest altitudes.  They often appear thin and wispy.  They are associated with fair weather.
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* The [[Great Basin]].
  
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;Cumulus: Cumulus clouds are usually puffy and often have very distinct edges and usually a noticeable vertical development. They often have a popcorn-like appearance. Cells can be rather isolated or they can be grouped together in clusters. The first rain to fall out of the base of a cumulus cloud evaporates into the air beneath, cooling the air - often by several degrees. This cooled air descends, and the more it is cooled the more rapidly it descends. Thus instead of air rising into a cloud we have not only rain falling out the cloud, but air as well. This is why cool and rainy weather is assocaited with cirrus clouds.
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===Atmospheric waves===
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As air flows over mountain barriers, orographic lift can create a variety of wave effects, which produce vertical air motion. If the air mass is close to the dew point, the waves may show as a variety of leeward clouds<ref name="Whiteman" />:
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* [[Lenticular cloud]]s are stationary lens-shaped clouds that form at high altitudes, normally aligned at right-angles to the wind direction. Orographic lifting creates a wave which creates the condition for cloud formation.
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* A ''cap cloud'' is a special form of the lenticular cloud with a base low enough that it forms around and covers the peak, capping it.<ref name="Whiteman" />
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* [[Wave cloud]]s are lenticular clouds, created when an [[air mass]] passes over a geographic feature and a standing wave forms downwind.  
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* A ''banner cloud'' is a cloud that forms downstream from the upper lee slopes of isolated, steep-sided mountains. This cloud is similar to the condensation observed off the tips of high-performance aircraft wings when they operate in humid conditions; it is created by the vortices and local uplifting in the air caused by the orographic lifting as the wind passes the mountain. The most famous such cloud forms routinely in the lee of the [[Matterhorn]].<ref name="Whiteman" /><ref>[http://www.atmos.washington.edu/gcg/Atlas/phot_oro03.html Example of a banner cloud forming in the lee of the Matterhorn.]</ref>.
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* A ''foehn wall'' is an extensive cloud formed along and parallel to the ridge line. The wall appears stationary, while the wind flows through; moisture condenses on the upslope and evaporating when it descends the lee slope. When viewed as one faces it, it often appears to have an abrupt wall like edge. The foehn wall is a common feature along the [[Front Range]] of the [[Colorado]] Rockies.<ref name="Whiteman" />
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* A ''[[Chinook wind#Chinook arch|chinook arch cloud]]'' forms above a mountain range, usually at the beginning of a chinook wind as a resulting of orographic lifting over the range. It appears when seen from downwind to form an arch over the mountain range. A layer of clear air separates it from the mountain.<ref name="Whiteman" />
  
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;Stratus: Stratus clouds belong to a class characterized by horizontal layering with a uniform base, as opposed to convective clouds that are as tall or taller than wide (these are termed cumulus clouds). More specifically, the term stratus is used to describe flat, featureless clouds of low altitude varying in color from dark gray to nearly white. These clouds are essentially fog that is above ground level and are formed either through the lifting of morning fog or when cold air moves at low altitudes over a region. These clouds do not usually bring precipitation, although if sufficiently low in altitude to become fog, drizzle or mist may result.
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===Leeward winds===
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Downslope winds occur on the leeward side of mountain barriers when a stable air mass is carried over the mountain by strong winds that increase in strength with height. Moisture is removed and latent heat released as the air mass is orographically lifted. As the air mass descends, it is compression heated. The warm [[Föhn wind]], locally known as the [[Chinook wind]],  [[Bergwind]] or [[Diablo wind]] or "Nor-Wester" depending on the region, provide examples of this type of wind, and are driven in part by latent heat released by orographic lifting induced precipitation.  
  
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;Nimbus: Nimbus clouds are dark, precipituous clouds. Nimbus is a Latin word meaning cloud or rain storm.  These are commonly called "thunderclouds."
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A similar class of winds, the [[Sirocco]], the [[Bora]] and [[Santa Ana wind]]s, are examples where orographic lifting has limited effect since there is limited moisture to remove in the [[Sahara]]n or other air masses; the Sirocco, Bora and Santa Ana are driven primarily by compression heating.
  
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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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==See also==
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* [[Orography]]
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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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* [[Rain shadow]] are a result of moisture removal by orographic lifting.
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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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[[Image:Jet Stream.jpg|thumb|250px|The main jet streams flow from the west in the upper atmosphere]]
 
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Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 11 kilometres (36,000 ft) above the surface of the Earth. They form at the boundaries of adjacent air masses with significant differences in temperature, such as of the polar region and the warmer air to the south.  For this reason, areas between the pole and the jet stream are cold, and area between the equator and the jet stream are warm.  As the jet stream shifts along the north-south direction, the weather shifts as well.
 
  
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Meteorologists now understand that the path of the jet stream steers cyclonic storm systems at lower levels in the atmosphere, and so knowledge of their course has become an important part of weather forecasting. Jet streams also play an important part in the creation of super cells, the storm systems which create tornados.
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{{commonscat|Orographics Clouds}}
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<br style="clear:both">
 
  
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===b. Volcano eruption===
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==References==
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When a volcano erupts, it sends incredible amounts of volcanic ash into the atmosphere. This is enough to decrease the amount of sunlight that reaches the earth, causing a temporary (though sometimes devastating) global cooling. It also affects the intensity of the colors in the sunset for years.
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<!--See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref(erences/)> tags-->
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<references/>
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==10. Make a drawing showing the water cycle in weather.==
 
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[[Image:Water cycle.png|thumb|500px|The movement of water around, over, and through the Earth is called the water cycle.]]
 
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The water cycle is the continuous movement of water over, above, and beneath the Earth's surface. It is powered by solar energy, and because it is a cycle, there is no beginning or end. As water moves around in the hydrosphere, it changes state among liquid, vapour, and ice. The time taken for water to move from one place to another varies from seconds to thousands of years, and the amount of water stored in different parts of the hydrosphere ranges up to 1.37 billion km³, which is contained in the oceans. Despite continual movement within the hydrosphere, the total amount of water at any one time remains essentially constant.
 
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<br style="clear:both">
 
  
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==11. Make a simple wind vane or rain gauge.==
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[[Category:Climate forcing agents]]
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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===
 
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==References==
 
  
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[[Category:Adventist Youth Honors Answer Book|{{SUBPAGENAME}}]]
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[[es:Nube orográfica]]
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[[fr:Onde orographique]]
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[[fi:Orografinen pilvi]]
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[[it:Sollevamento orografico]]

Revision as of 11:21, 10 January 2007

This wave cloud pattern formed off of the Île Amsterdam in the far southern Indian Ocean, due to orographic lift of an airmass by the island, producing alternating bands of condensed and invisible humidity downwind of the island as the moist air moves in vertical waves and the moisture successively condenses and evaporates.

Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it expands and cools adiabatically. This cooler air cannot hold the moisture as well as warm air and this effectively raises the relative humidity to 100%, creating clouds and frequently precipitation.

Effects of orographic lifting

Precipitation

Precipitation induced by orographic lift occurs in many places throughout the world. Examples include:

Rain shadowing

A lenticular cloud in New Mexico.
A cap cloud.
Wave clouds.
Koryaksy volcano, Kamchatka, Russia, showing banner clouds streaming to the right from the peaks.
File:Chinook19.11.05.JPG
Chinook arch in Calgary, Alberta, November 19, 2005
A view of the Front Range of the Rockies capped by a foehn wall.
Main article: Rain shadow

The highest precipitation amounts are found slightly upwind from the prevailing winds at the crests of mountain ranges, where the relief and therefore the upward lifting is greatest. As the air descends the lee side of the mountain, it warms and dries, creating a rain shadow. On the lee side of the mountains, sometimes as little as 15 miles (25 km) away from high precipitation zones, annual precipitation can be as low as 8 inches (200 mm) per year.&

Areas where this effect is observed include:

Atmospheric waves

As air flows over mountain barriers, orographic lift can create a variety of wave effects, which produce vertical air motion. If the air mass is close to the dew point, the waves may show as a variety of leeward clouds&:

  • Lenticular clouds are stationary lens-shaped clouds that form at high altitudes, normally aligned at right-angles to the wind direction. Orographic lifting creates a wave which creates the condition for cloud formation.
  • A cap cloud is a special form of the lenticular cloud with a base low enough that it forms around and covers the peak, capping it.&
  • Wave clouds are lenticular clouds, created when an air mass passes over a geographic feature and a standing wave forms downwind.
  • A banner cloud is a cloud that forms downstream from the upper lee slopes of isolated, steep-sided mountains. This cloud is similar to the condensation observed off the tips of high-performance aircraft wings when they operate in humid conditions; it is created by the vortices and local uplifting in the air caused by the orographic lifting as the wind passes the mountain. The most famous such cloud forms routinely in the lee of the Matterhorn.&&.
  • A foehn wall is an extensive cloud formed along and parallel to the ridge line. The wall appears stationary, while the wind flows through; moisture condenses on the upslope and evaporating when it descends the lee slope. When viewed as one faces it, it often appears to have an abrupt wall like edge. The foehn wall is a common feature along the Front Range of the Colorado Rockies.&
  • A chinook arch cloud forms above a mountain range, usually at the beginning of a chinook wind as a resulting of orographic lifting over the range. It appears when seen from downwind to form an arch over the mountain range. A layer of clear air separates it from the mountain.&

Leeward winds

Downslope winds occur on the leeward side of mountain barriers when a stable air mass is carried over the mountain by strong winds that increase in strength with height. Moisture is removed and latent heat released as the air mass is orographically lifted. As the air mass descends, it is compression heated. The warm Föhn wind, locally known as the Chinook wind, Bergwind or Diablo wind or "Nor-Wester" depending on the region, provide examples of this type of wind, and are driven in part by latent heat released by orographic lifting induced precipitation.

A similar class of winds, the Sirocco, the Bora and Santa Ana winds, are examples where orographic lifting has limited effect since there is limited moisture to remove in the Saharan or other air masses; the Sirocco, Bora and Santa Ana are driven primarily by compression heating.

See also

Template:Commonscat

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Whiteman, C. David (2000). Mountain Meteorology: Fundamentals and Applications. Oxford University Press. ISBN 0-19-513271-8.
  2. ↑ Example of a banner cloud forming in the lee of the Matterhorn.

es:Nube orográfica fr:Onde orographique fi:Orografinen pilvi it:Sollevamento orografico

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