Watch the following video:
Saturday, October 22, 2016
Sunday, October 16, 2016
Depressions
Depressions are areas of low atmospheric pressure which produce cloudy, rainy and windy weather. These low-pressure systems often begin in the Atlantic, moving eastwards towards the UK. They are responsible for the UK's changeable weather.
The diagram shows a depression with a leading warm front and a trailing cold front moving from west to east across Britain.
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Diagram of a depression
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Air Pressure
Air is light but because there is so much of it above us, it exerts a pressure on us. Air pressure is measured by a barometer. The units used are millibars. The greater the reading, the higher the pressure.
A high-pressure system is called an anticyclone. Air falls in an anticyclone so no clouds are formed. In summer, high pressure usually results in clear skies, gentle breezes and fine weather. In winter high pressure leads to clear skies and colder conditions.
An area of low pressure is called a depression. Air rises in a depression so clouds and rainfall are formed. Depressions therefore bring unsettled weather and rain. Winds are normally stronger. They usually form over the Atlantic Ocean and are carried across Britain by westerly winds.
See the following video on anticyclone and depression.
IGCSE Past Papers
| Theme 1 | Pop growth rates and life expectancy, Named e.g. of internatinal migration, causes Urban land use and conflict, features of named squatter set. |
| Theme 2 | Drainage basin; formation of waterfall; formation of waterfall Plate boundaries, impact of eq; why live near named volc |
| Theme 3 | Why tourists to Maldives, benefits and disadvantages. Named e.g. damage to nat envir by tourism |
| Theme 1 | Pop density, India. Named e.g. of country, why high birth rate CBD issues; Named e.g. of urban sprawl and impact |
| Theme 2 | River valley and processes, Weathering. TRF and ecosystem. Named e.g. how trf benefits people |
| Theme 3 | Manuf employment; adv and disadv of living in ind areas. Named e.g. ind area and impact on nat envir Water supply and conflict. Named e.g. of country or area, describe how energy is produced. |
| Theme 1 | Pop structure. Named country, problems of ageing pop Urbanisation, problems and solutions. Named e.g.problems of urban sprawl |
| Theme 2 | Coastal landforms, beaches, named coral reefs and formation, UK flood, cause and impact; Weathering |
| Theme 3 | Tourism, adv and disadv. Named e.g. explain how phys and human factors encouraged tourism Agr. Named farm study |
| Theme 1 | Migration, issues. Named e.g. probs caused by under pop Urban areas and issues. Named e.g. solutions to traffic problems |
| Theme 2 | Coastal landforms, proc. coral reef, formation of spit. Named e.g. how nat envir provides opportunites and causes problems Rain in desert and TRF. Adapt of veg in desert. D&E charac of TRF veg |
| Theme 3 | Tourism, growth and issues. Named e.g. impact of tourism on nat envir Conservation and sus devel. Named e.g. of devel of renewable energy |
| Theme 1 | Pop structure, issues. Named e.g. ofprobs of ageing pop Cause and impact of urbanisation. Cause of devel of squatter set. Named e.g. for solutions |
| Theme 2 | Volc, distrib, benefits and probs. Name e.g. of volc and cause of eruption Cause and impact of deforestation. D&E trf climate |
| Theme 3 | Farming, large scale and intensive. Named e.g. subsistence Water supply, food shortage |
| Theme 1 | Pop density, cause and issues. Named e.g. of cause of international migration Traffic congestion, cause and solution. Named e.g. of solution to improve poor qual housing |
| Theme 2 | River proc D&E meander. Named e.g. of impact of flood Deforestation and TRF, issues. Named e.g. D&E features of TRF climate |
| Theme 3 | Issues of location of manuf ind. Causes of global warming GDP and ind. Benefits of tourism in LEDC, Named e.g. impact of tourism on nat envir |
| Theme 1 | Causes for differences in pop density Settlement hierarchy |
| Theme 2 | Weather instruments; problems of tropical storm Tropical rainforest: climate, vegetation and deforestation Tropical desert; d & e charateristics. |
| Theme 3 | Food shortages, soil erosion, farming as a system Atmospheric pollution; sustainable development; developemnt of energy supplies for a named country |
| Theme 1 | Population: DR & BR, pop pyramid, youthful pop. issues. Impact of AIDS Traffic flow in Bangalore,issues about attempts to improve congestion generally. Improving squatter set, with named eg |
| Theme 2 | Meander, living on a flood plain, formation of delta Volcano: impact of living near, issues and benefits. Effects of tropical storms. LEDC/MEDC |
| Theme 3 | Tourism, wind power. Causes and effects of air or water pollution Water, access, shortage, availability |
| Theme 1 | Pop pyramid LEDC/MEDC. Ageing pop issues. Pop policy issues Shopping centre, issues, sphere of influence. CBD features |
| Theme 2 | Meander cross section, flood plain. Adv and disadv of living in delta Sichuan earthquake short and long term effects. Cause of named earthquake. |
| Theme 3 | Location of hi tech inds. Named manuf or proc inds reasons for growth. Use of water, impact of water shortage |
June 09 Paper 1
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| Theme 1 | Population:Migration; pop density Urban: Amman land use and issues; housing shortage problems and solutions |
| Theme 2 | Coasts: wave cut platform and cliffs, coral reefs; Formation of sand dunes Types of weathering; limestone weathering; Hazard, (storm, flood drought) cause and impact |
| Theme 3 | Employment structure, inputs, proc and outputs, manuf envir issues, location of hi tech inds Turkey; commercial agriculture and tourism, food shortages |
| Theme 1 | Pop policis in Russia. Named eg of country with high pop growth, reasons for. Location and function of Nice. Site of rural set. Reasons for migration away from named rural area in LEDC |
| Theme 2 | Cause of Indonesian earthquake, short and long term effects of earhquake. Why people still live in earthquake areas. TRF ecosystems, effects of deforestation. D&E features of desert climate |
| Theme 3 | Renewable energy, in MEDC and impact on nat envir D&E location of named power station CO2 emissions. Impact of global warming |
| Theme 1 | BR and DR, probs of ageing pop. Benefit of immigration to MEDC. Named area, d&e reasons for variations in pop density Rural set pattern, migration away from rural areas in LEDC. Reasons for devel of areas in urban: steet market, port inds, old ind area. Named urban area, effect on nat envir |
| Theme 2 | Nat hazards, impact on LEDCs. Cause of eq, Named eq, short and long term effects Weather data and insturments. Diff between clouds. Cb effect. D&E effect of humans on TRF |
| Theme 3 | Energy in Canada, renewable. Fuelwood, impact on humans and nat envir. Tri graph. Ind structure. Prim sector in LEDC. Ind as system. Effect on envir of manuf. Named eg of high tech ind and location |
| Theme 1 | BR and life expectancy, Mali. Using eg. why migrate? Push and pull factors CBD, hierarchy of set. Sphere of influence. Urban sprawl and effect on human and nat envir |
| Theme 2 | Mojave Desert, cause, cause and effect on vegetation. Human activ and TRF or desert Fold mts. and diff plate boundaries. Volcanoes and boundaries. Why people live inareas ofeither, volcanic eruptions; earthquakes, tropical storms, flooding, drought |
| Theme 3 | Pastoral farming. NZ. Issues of agriculture, manufacturing industry, energy production Water; cause for devel of tourism |
| Theme 1 | Pop pyramids and ageing population Land use models; shanty towns and solutions |
| Theme 2 | Weather instruments, describe weather data; problems of drought River valley cross profile and process, waterfalls formation and benefits; named river cause of flooding |
| Theme 3 | LEDC tourism, costs and benefits and sustainability Types of energy, fossil fuels; development of renewable's |
Nov 2007
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| Theme 1 | Australia, migration. Low-density areas. Causes of high population growth. MEDC suburban areas. Problems of rural urban fringe. |
| Theme 2 | LSD, spit formation, sand dune formation. Opportunities for people who live in coastal areas. Hurricane Katrina, impact long and short-term effects of either volcano, earthquake, drought |
| Theme 3 | food shortage, Aid. farming as a system. Dam construction, South Africa, issues. causes and effects of either air or water pollution. |
June 2007
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| Theme 1 | birth and death rates,MEDC, LEDC population pyramid, Norway, ageing population Problems of over population growth of population in Calcutta, problems and solutions reasons for international migration |
| Theme 2 | California earthquakes, causes and impact long and short-term effects of either volcano, tropical storm, drought formation of floodplain, Delta ways of reducing flooding |
| Theme 3 | manufacturing industry, systems, location of high-tech industry tourism in Cuba, benefits and issues. environmental affects of either mining agriculture transport or energy. |
June 2004
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| Theme 1 | issues of population growth in Nigeria. Changes in fertility rates in MEDC's. sphere of influence, land use in MEDC city, issues of migration within a city |
| Theme 2 | Stevenson screen, weathering (temperature v rainfall graph) Pacific Ring of Fire, plate boundaries. earthquakes, short and long-term effects. |
| Theme 3 | industrial structure. growth of High-tech industry environmental issues |
Convectional Rainfall
Convectional rainfall is associated with warm climates. The sun heats up the ground causing any moisture in the ground or stored on leaves, etc to evaporate. This evaporated moisture rises and as it rises will cools. It then condenses to form clouds, resulting in rain.
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| Convectional Rainfall |
Watch the following video:
Frontal Rainfall
Rain can be created when two air masses meet. If a mass of cold air meets a mass of warm air the two are unable to mix. As the cold air is denser (heavier) than the warm air, it forces the warm air mass to rise and move over the cold air. As the warm air rises, it begins to cool and condense creating clouds. These clouds then bring with them rainfall.
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Frontal Rainfall Watch the following video: Frontal Rainfall Frontal Rainfall: Diagram and Explanation |
Relief Rainfall
The shape of the land is called the relief. When the wind meets an area of highland it is forced to rise. As this air rises it cools and condenses to form clouds. These clouds bring with them rain, meaning that on one side of the mountain there will be heavy rain. As the wind then descends down the opposite side of the mountain, it warms and has now lost most of its moisture. This creates an area of low rainfall, called a rain shadow.
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Relief Rainfall |
Watch the following video:
Types of Rainfall
The type of rainfall a place experiences will be determined by the location and the physical geography of the place.
Factors Influencing Climate: Ocean Currents
Ocean currents can have a dramatic effect on the climate of a location. These currents may bring warmer waters, which will result in a place experiencing higher temperatures than expected. For example, the UK is has a warm climate due to the North Atlantic Drift, which brings warm water from the Caribbean. Where as some places experience cold currents which lowers their temperature.
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The world’s ocean is crucial to heating the planet. While land areas and the atmosphere absorb some sunlight, the majority of the sun’s radiation is absorbed by the ocean.
Ocean currents act much like a conveyer belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth’s surface. Without currents, regional temperatures would be more extreme—super hot at the equator and frigid toward the poles—and much less of Earth’s land would be habitable.
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There are warm and cold currents that circulate our planet and depending on which one is present on the coast this will impact temperature.
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The world’s ocean is crucial to heating the planet. While land areas and the atmosphere absorb some sunlight, the majority of the sun’s radiation is absorbed by the ocean.
Particularly in the tropical waters around the equator, the ocean acts a as massive, heat-retaining solar panel. Earth’s atmosphere also plays a part in this process, helping to retain heat that would otherwise quickly radiate into space after sunset.
The ocean doesn't just store solar radiation; it also helps to distribute heat around the globe. When water molecules are heated, they exchange freely with the air in a process called evaporation. Ocean water is constantly evaporating, increasing the temperature and humidity of the surrounding air to form rain and storms that are then carried by trade winds, often vast distances. In fact, almost all rain that falls on land starts off in the ocean. The tropics are particularly rainy because heat absorption, and thus ocean evaporation, is highest in this area.
Outside of Earth’s equatorial areas, weather patterns are driven largely by ocean currents. Currents are movements of ocean water in a continuous flow, created largely by surface winds but also partly by temperature and salinity gradients, Earth’s rotation, and tides (the gravitational effects of the sun and moon). Major current systems typically flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere, in circular patterns that often trace the coastlines.
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| Illustration of major ocean currents throughout the globe. Ocean currents act as conveyer belts of warm and cold water, sending heat toward the polar regions and helping tropical areas cool off. Watch the video on the Role of Ocean Currents on Climate |
Factors Influencing Climate : Relief
Relief is the shape of the land, so how mountainous it is. This can affect the temperature as temperatures will face by 1°C for every 100 meters gained in altitude. Relief can also affect the levels of precipitation, with mountainous areas experiencing high levels of rainfall.
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The higher up you go the colder it gets. Typically you lose 1°C with every 100 meters that you go up in altitude. This is because there is less atmosphere to retain the sun's heat (think of it as a duvet, the thicker it is the warmer it is).
The higher up you go the colder it gets. Typically you lose 1°C with every 100 meters that you go up in altitude. This is because there is less atmosphere to retain the sun's heat (think of it as a duvet, the thicker it is the warmer it is).
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| Altitude and its Effect on Weather and Temperature |
Watch the following videos:
Factors Influencing Climate: Prevailing Wind
The prevailing wind is the direction which the wind normally blows from.
If it blows over an area of warm land the wind will be warmer, causing temperatures to be higher. The opposite is true if the wind blows over a cool area.
Prevailing winds can also pick up moisture. So if the wind has blown over an area of water it will increase the levels of rainfall. Whereas if the wind has blown over a dry area then it will contain no moisture so rainfall will be very low.
If it blows over an area of warm land the wind will be warmer, causing temperatures to be higher. The opposite is true if the wind blows over a cool area.
Prevailing winds can also pick up moisture. So if the wind has blown over an area of water it will increase the levels of rainfall. Whereas if the wind has blown over a dry area then it will contain no moisture so rainfall will be very low.
Watch the following video:
Factors Influencing Climate: Distance from the Sea
The sea is not very quick to heat up during the summer as it is such a large volume of water. This means that places near the sea are often not as warm during the summer. However, the sea also takes a long time to cool down. This means that places near the sea are not as cold in the winter.
Where as the land heats up very quickly but also cools down very quickly. Meaning that places inland have hot summers but cold winters.
Where as the land heats up very quickly but also cools down very quickly. Meaning that places inland have hot summers but cold winters.
Watch the following videos:
Factors Influencing Climate: Latitude
At the equator the sun is directly overhead. This means that the sun’s rays are more focused, as they only have to heat up a small area of land. Where as at the poles the sun is at a lower angle in the sky, this means the sun’s rays are spread out over a larger area so cannot heat the ground enough to cause high temperatures.
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Latitude affects temperature in three ways:
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| Latitude |
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Latitude affects temperature in three ways:
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Watch the following videos:
Presenting Weather Data Via Synoptic Chart
A synoptic chart is any map that summarises atmospheric conditions over a wide area at any given time. They are used to give an overview of the weather conditions, using data from a number of weather stations and satellites. By working together to create these maps meteorologists can work together to make more accurate predictions. There are many different types of weather map, but they all use the same symbols which have been internationally agreed. Weather symbols can seem confusing until you look for patterns.
Saturday, October 15, 2016
How to Measure Cloud Cover
Clouds are usually measured on oktas (0 oktas = clear sky, 8 oktas = total coverage).
Students can do basic calculations by dividing a mirror into multiples of 8.
They can then count the number of full or partial squares – convert to oktas e.g. if 6 out of 16 squares are filled then cloud cover is 3 oktas.
Students can do basic calculations by dividing a mirror into multiples of 8.
They can then count the number of full or partial squares – convert to oktas e.g. if 6 out of 16 squares are filled then cloud cover is 3 oktas.
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| Measuring Cloud Cover |
Watch the following videos:
Clouds and Cloud Types
Clouds are a collection of water droplets or ice crystals. The warmer the air temperature, the more water vapour (gas) that the air can hold. However, when the air starts to cool, water vapour starts to condense as long as it has condensation nuclei to condense around.
Cirrus
Cirrus
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| Cirrus Clouds |
- Found high in the atmosphere – usually over 5,500 metres
- Common throughout the world
- Thin and wispy in appearance
- Move fairly quickly
Stratus
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| Stratus Clouds |
- Low level – below 2000m and sometimes reaching ground.
- Usually grey and colour and move fast.
- Can produce light rain and snow
Cumulonimbus
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| Cumulonimbus Clouds |
- Large clouds up to 10km high and across.
- They resemble giant cauliflower.
- Produce rain, thunder and lightening
- Usually found in spring and summer
Cumulus
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| Cumulus Clouds |
- Fairly low clouds with bottom between 600m and 1200m
- Look like lumps of cotton wool
- Can produce light rain
- Individual clouds have a short life cycle
See the following video on Cloud Types
There are ten main types of which can be split into three categories according to height.
Look at this diagram, you can see the sub divisions of the clouds.
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| Cloud Types |
High clouds are between 5500 and 14000 m above the ground, they are usually composed solely of ice crystals;
- cirrus - white 'filaments
- cirrocumulus - small rippled elements
- cirrostratus - transparent sheet, often with halo
Medium clouds, between 2000m and 7000m are usually composed of water droplets or a mixture of ice crystals and water droplets:
- altocumulus - generally white, layered, rippled elements,
- altostratus - grey thin layer
- nimbostratus - thick layer, dark with possibility of rain or snow
Low clouds below 2000m, usually made up of water droplets;
- stratocumulus - layered series of rounded rolls, generally white;
- stratus - layered uniform grey
- cumulus - 'white cauliflower' clouds with flat base;
- cumulonimbus - large dark towers, often with 'anvil' tops, associated with heavy rain and thunderstorms
Weather Maps
Weather maps can display a whole variety of data. The map below is fairly simple and simply shows:
- Temperature
- Wind speed
- Wind direction
- Likely weather e.g sun, rain cloud
Other weather maps can be more detailed and show information like:
- Air pressure (using isolines to show areas of the same pressure (millibars))
- Cloud cover (oktas)
- Humidity (%)
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| Weather Map |
Climate Graphs
Climate graphs show the average temperature and rainfall for a city or region over the year. Temperature is always shown in the form of a line graph. Some climate graphs have the average maximum temperature and the average minimum, others just have the overall average temperature. The line graph is normally coloured in red. Rainfall is always shown in the form a bar graph and normally coloured in blue.
Climate graphs are very good for showing averages, but they don't show anomalous years, because it is based on averages and it doesn't show things like the number of days of rain. A month may have 50mm of rain, but we don't know if that comes in small rain showers or one big thunderstorm.
When reading climate graphs you should look for trends and anomalies. On the graph below the temperature trend is fairly easy to read. It increases from January to July and then decreases until December. The rainfall data is not as straight forward because some of the early months fluctuate (go up and down). Whenever you are describing graphs, remember it is very important to use figures with the correct unit. Occasionally you maybe asked to give the temperature or rainfall range - this is the difference between the highest and lowest total.
Climate graphs are very good for showing averages, but they don't show anomalous years, because it is based on averages and it doesn't show things like the number of days of rain. A month may have 50mm of rain, but we don't know if that comes in small rain showers or one big thunderstorm.
When reading climate graphs you should look for trends and anomalies. On the graph below the temperature trend is fairly easy to read. It increases from January to July and then decreases until December. The rainfall data is not as straight forward because some of the early months fluctuate (go up and down). Whenever you are describing graphs, remember it is very important to use figures with the correct unit. Occasionally you maybe asked to give the temperature or rainfall range - this is the difference between the highest and lowest total.
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| Edinburg's Climate Graph |
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| Climate Graph |
Cloud Cover
It is also possible to count day light hours, sunshine hours or cloud cover.
To calculate day light hours you need to record the time between sun rise and sun set.
To calculate sun shine hours is a lot harder, because you have to time every time the sun comes out (stopwatch).
To calculate cloud cover a mirror is often used. You divide the mirror into squares and then place the mirror on the ground. The mirror will reflect the clouds and you can count the number of squares covered or partially covered by cloud. You can do this as a percentage or convert to oktas which is the normal measurement of cloud cover. You have to take several readings to avoid anomalous results.
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To calculate day light hours you need to record the time between sun rise and sun set.
To calculate sun shine hours is a lot harder, because you have to time every time the sun comes out (stopwatch).
To calculate cloud cover a mirror is often used. You divide the mirror into squares and then place the mirror on the ground. The mirror will reflect the clouds and you can count the number of squares covered or partially covered by cloud. You can do this as a percentage or convert to oktas which is the normal measurement of cloud cover. You have to take several readings to avoid anomalous results.
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| Scale of cloud cover measured in oktas (eighths) with the meteorological symbol for each okta |
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Anemometers
Anemometers measure wind speed.
Wind speed is normally measured in mph or kph, but can also be measured in m/s (metres a second).
Digital anemometers are very accurate, but the more basic plastic ones that many schools have aren't very good or accurate at recording light winds.
Anemometers are normally placed on top of buildings so that they are not protected from the wind and so they don't experience channeling of wind e.g. if an anemometer was placed in a corridor where wind was forced through the readings would be higher than normal.
Wind speed is normally measured in mph or kph, but can also be measured in m/s (metres a second).
Digital anemometers are very accurate, but the more basic plastic ones that many schools have aren't very good or accurate at recording light winds.
Anemometers are normally placed on top of buildings so that they are not protected from the wind and so they don't experience channeling of wind e.g. if an anemometer was placed in a corridor where wind was forced through the readings would be higher than normal.
Watch the following videos:
Wind Vanes
Wind vanes are used to check the direction of the wind.
Compass points are used to give wind direction.
Wind is measured in the direction that the wind is coming from.
Wind vanes are often placed on top of buildings so that they are fully exposed to the wind.
When using a wind vane you need to use a compass to make sure that it is properly aligned.
Compass points are used to give wind direction.
Wind is measured in the direction that the wind is coming from.
Wind vanes are often placed on top of buildings so that they are fully exposed to the wind.
When using a wind vane you need to use a compass to make sure that it is properly aligned.
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| Wind Vane |
Watch the following videos:
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