Harden Up - Protecting Queensland

Time 2020-10-27 15:07:20

Web Name: Harden Up - Protecting Queensland

WebSite: http://hardenup.org

ID:96170

Keywords:

Up,Harden,Queensland,

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Green Cross Australia is a not for profit organisation who deliver digital projects that help people in practical ways adapt to our changing climate, embrace sustainable living and build resilient communities. Find out about our other projects… greencrossaustralia.org What will our Queensland coast look like in the future? See the effects of sea level rise through this community photography initiative. Find out more It Could Happen TomorrowCyclone HypotheticalA cyclone is hitting the east coast!Follow its path and see the communities affected and damage caused by a storm surge.Find out more What does that mean? As you explore the site, look for underlined words and the jargon buster icons to help you understand the facts. Check out the Jargon Buster Protecting Queensland Recent years have been tough for Queenslanders. We have endured severe storms, floods, droughts and cyclones. Our weather can be extreme and we need to stay strong. On this website you can see 150 years of local severe weather history in your area. After understanding the weather patterns in your area, you can use our planning tool to prepare your home, pets, family and community for major weather events that lie ahead. Together we can protect Queensland. Find out more A message for people affected by the severe weather events in Queensland, and an invitation to tell your story. Find out more I just started a Harden Up plan to get ready for severe weather in my suburb. Natural hazards such as cyclones, severe storms bushfires and floods are an inevitable part of Queensland's climate. We can't afford to ignore these hazards. On the Harden Up site you can see past weather events that have impacted your community and use an interactive planning tool to prepare for them. These tips can protect your home, pets, and kids. Please join me in preparing our community for extreme weather. www.hardenup.orgThe sideways movement of air in the lower atmosphere due to thedifferences in air pressure (commonly calledwind). Process of transfer of air mass propertiesby the velocity field of the atmosphere.AnomalyThe departure of an element from its long-period average valuefor the location concerned. For example, if the maximum temperaturefor June in Melbourne was 1 degree Celsius higher than thelong-term average for this month, the anomaly would be +1 degreesCelsius. The current international standard is to use the 30 yearaverage from 1961 to 1990 as the long-term average.AnticyclonesAtmospheric circulations that rotate anti-clockwise in thesouthern hemisphere. Anticyclones are areas of higher pressure andare generally associated with lighter winds and fine and settledconditions.Australian Height Datum (AHD)An average of the level of the sea around Australia in betweenhigh and low tide. It is used as the zero point when measuring ormarking water height (measured straight up) e.g. on a map or floodmarker. As an example, thirty metres above this 'sea level' wouldbe written as '30m(AHD)'.BarometerA tool to measure air pressure which lets us predict change inweather.Beaufort wind scaleA scale that uses observations of the effects of wind toestimate its speed.BlizzardViolent and very cold wind which is loaded with snow, some ofwhich has been raised from snow covered ground.Carbon dioxideA gas (CO2) present in the atmosphere which plays animportant role in the greenhouse effect.Celsius temperature scaleThermodynamic scale of temperature. Temperature in degreesCelsius can be obtained from value in degrees Fahrenheit by thefollowing formula: C = (F - 32) x 5/9Chance of any rainChance of rain describes the likelihood of receiving ameasurable amount of rain ( 0.2mm) during the day at thatlocation. For example, if the chance of rain for Mildura is 30%, itmeans that on 3 out of 10 days with similar weather conditionsrainfall will be measured in the Mildura rain gauge. Where theremay be a 30% chance of any rainfall, there is also a 70% chance ofnot receiving any rainfall at all.ChlorofluorocarbonsChemicals that release chlorine atoms that destroy ozone high inthe atmosphere.Cirrus cloudHigh cloud, delicate, hair-like and feathery looking.ClimateThe atmospheric conditions for a long period of time, andgenerally refers to the normal or mean course of the weather.Includes the future expectation of long term weather, in the orderof weeks, months or years ahead.CloudA group of water drops or ice crystals that can be seen in thesky, caused by water vapour rising and cooling. Rain, hail or snowfalls when the cloud can hold no more water or ice.Cloud coverForecasting terms:Cloudy: More cloud than clear sky. For example, during the daythe sun would be hidden by cloud for a lot of time.Overcast: Sky completely covered with cloud.Combined Sea and SwellAlso known as total wave height, or significant wave height.Combined sea and swell describes the combined height of the sea andthe swell that mariners experience on open waters. The height ofthe Combined sea and swell refers to the average wave height of thehighest one third of the waves.ConvectionThe movement of warm air, rising off the land, which helps tomake cloud, local breezes, wind and thunderstorms.Cumulonimbus cloudHeavy, puffy, heaped, dark very tall clouds often bringing rain.Some have an anvil shaped head. Sometimes called a 'thunderhead'.CumulusClouds with a woolly, heaped appearance that often producerain.CyclogenesisThe rapid development of a low or intensification of apre-existing one.CycloneIn Australia, ­ a cyclone is a large clockwise loop of lowpressure air that usually brings very strong or damaging winds,unsettled weather, cloudiness and very heavy rainfall.(NOTE: Anticyclones - In Australia, an anticyclone is a largeanti-clockwise loop of high pressure air, generally with lightwinds and fine and settled weather.)Cirrus cloudHigh cloud, delicate, hair-like and feathery looking, that maybe seen on 'fine' days.DesertThere are many different definitions which describe a desert. Ingeneral, arid areas (or deserts) are areas with lowprecipitation.DewDroplets of water deposited when air cools and the water vaporin it condenses.Dew-point temperatureThis is a measure of the moisture content of the air and is thetemperature to which air must be cooled in order for dew to form.The dew-point is generally derived theoretically from dry andwet-bulb temperatures, with a correction for the site's elevation.If the dry-bulb temperature is the same as the dew-point, the airis said to be saturated and the relative humidity is 100%.DownburstViolent and damaging downwards flow of air hitting the surfaceof the Earth violently, usually in a severe thunderstorm.DrizzleSteady(rain) in very small water droplets (less than 0.5 mm indiameter) very close to one another.DroughtDrought is a long, unusually dry period when there is not enoughwater for normal needs.Dry-bulb temperatureThis is the shade temperature (degrees Celsius) registered by amercury-in-glass thermometer exposed in a white louvered box ormeteorological screen which is raised on legs one metre above theground.Dry(As used by forecasters) Free from rain. Normally used whenpreceding weather has also been relatively dry, and dry weather isexpected to continue for a day or so.Dust stormA wind storm which carries large amounts of dust or sand highinto the air and may drop them far away e.g. dust from farm areasfalling on a city.East Coast LowsEast Coast Lows are intense low-pressure systems which happen onaverage several times each year off the eastern coast of Australia,in particular southern Queensland, NSW and eastern Victoria. Theygenerally last only a few days, but can become worse over night.They can bring very strong winds, very heavy rainfall and sometimescause coastal flooding.El NiñoNowadays, the term El Niño refers to the extensive warming ofthe central and eastern Pacific that leads to a major shift inweather patterns across the Pacific. In Australia (particularlyeastern Australia), El Niño events are associated with an increasedprobability of drier conditions.ENSOStands for El Niño-Southern Oscillation. 'El Niño' used hererefers to the warming of the oceans in the equatorial eastern andcentral Pacific; Southern Oscillation is the changes in atmosphericpressure (and climate systems) associated with this warming (hence'SouthernOscillation Index'' to measure these changes). 'ENSO' is usedcolloquially to describe the whole suite of changes associated withan 'El Niño' event - to rainfall, oceans, atmospheric pressureetc.Equatorial troughZone of relatively low pressure which lies between thesubtropical anticyclones of the two hemispheres.Fahrenheit temperature scaleThermodynamic scale of temperature. Temperature in degreesFahrenheit can be obtained from value in degrees Celsius by thefollowing formula: F = (9C/5) + 32FineDry weather with no rain of any kind, hail or snow.Flash FloodFlood of short duration with a relatively high peakdischarge.FloodA flood occurs when water inundates (covers) land which isnormally dry.Flood ForecastingScientific opinion, based on past records and on weather andwater conditions, about the likely height, amount of water, andtime a flood will probably happen, and go on for, at a particularplace on a river, stream or over land.Flood WarningOfficial advance notice that a flood may happen soon at acertain place or near a certain river.FogA dense mass of small water droplets or particles in the loweratmosphere.FrontThe boundary between air masses having differentcharacteristics.Front (Cold)In some regions along the polar front, cold dense air advancesequatorwards, causing warm air to be forced aloft over its slopingsurface. This portion of the polar front is known as a coldfront.Cold polar air is replacing warm tropical air.Front (Warm)In other regions along the front, warm air of lower densitymoves polewards, sliding over its sloping surface. This portion iscalled a warm front. Warm tropical air replaces cold polar air.FrostDeposit of soft white ice crystals or frozen dew drops onobjects near the ground; formed when surface temperature fallsbelow freezing point.Gale WarningA Gale Warning is a statement which warns of sea windsaveraging from 34 knots and up to 47knots (equal to about 60 - 85kph) in coastal waters and out at sea.Greenhouse effectA natural warming process of the earth. When the sun's energyreaches the earth some of it is reflected back to space and therest is absorbed. The absorbed energy warms the earth's surfacewhich then emits heat energy back toward space as longwaveradiation. This outgoing longwave radiation is partially trapped bygreenhouse gases such as carbon dioxide, methane and water vaporwhich then radiate the energy in all directions, warming theearth's surface and atmosphere. Without these greenhouse gases theearth's average surface temperature would be about 33 degreesCelsius cooler.Global radiationGlobal (short wave) radiation includes both that radiationenergy reaching the ground directly from the sun, and that receivedindirectly from the sky, scattered downwards by clouds, dustparticles etc.GustA gust is a sudden burst of stronger wind that usually onlylasts a few seconds.HailSmall roundish pieces of ice ('hailstones') (generally between 5and 50 millimetres across,) which fall from clouds as separate bitsor in clumps.Harden Up'Harden Up - Protecting Queensland' is a Green Cross Australiaproject. Harden Up is a statement of our ability as humans toendure natural disasters and be resilient to our changing climate.The term comes from a special report from the Australian StrategicPolicy Institute. The report,called Hardening Australia: Climate change and nationaldisaster resilience, encourages Australians tobuild resilience in infrastructure, business and the home and to beprepared for the unique risks that Australians will face as ourclimate changes.Heat waveA period of abnormally hot weather lasting several days.High pressureAtmospheric circulations that rotate anti-clockwise in theSouthern Hemisphere. Anticyclones are areas of higher pressure andare generally associated with lighter winds and fine and settledconditions.HumidMoisture in warm air.HumidityMoisture in warm air.Hurricane Force Wind WarningA Hurricane Force Wind Warning is a statement which warns ofwinds averaging 64 knots or more in coastal waters and high seasareas.HydrologyAn earth science concerned with the occurrence, distribution andcirculation of waters on and under the earth's surface, both intime and space, their biological, chemical and physical properties,their reaction with the environment, including their relation toliving beings.HydrometeorologyThe study of the atmospheric processes that affect the waterresources of the earth, including the study of the atmospheric andland phases of the hydrological cycle with emphasis on theinterrelationships involved.Indigenous WeatherIndigenous Australians have long held their own seasonalcalendars based on the local sequence of natural events.InshoreThe waters within 12 sea miles (about 22kms) of the coast.Inversion, temperatureA temperature inversion occurs when the temperature of airincreases with increasing height. Generally the temperaturedecreases with height in the lower atmosphere, called thetroposphere. Low-level inversions generally form on clear calmnights due to cooling of the ground through loss of heat byradiation. The warm air on the ground is replaced by cooler air atthe surface resulting in a temperature inversion. The inversioncreates a boundary layer that restricts vertical motion and mixingof air between the two air masses either side. Low-level inversionsact like a lid to trap pollutants resulting in smog over ourcities.IsobarsLines on weather maps running through places which have the sameair pressure.Jet streamA powerful current of air high above the Earth.KnotMeasure of wind speed equal to about 1.8 km per hour.Køppen's classification of climatesClassification of climate based on annual and monthly means oftemperature and precipitation (rainfall) which also takes intoaccount the vegetation limits. It is a tool for presenting theworld pattern of climate and for identifying important deviationsfrom this pattern.King tideOn Australia's east coast, the highest tides happen during thewinter months of June, July and August, and the summer months ofDecember, January and February. The two highest tides, one inwinter and one in summer, are known as the 'king tides'.Land BreezeA local offshore wind. At night, when the land cools morequickly, and to a greater extent, than the sea, the land breezecirculation is set up. Cooler air from the land flows offshore toreplace the warm air rising over the sea. The air in contact withthe sea warms and expands and the resulting changes in the pressureand temperature differences and distributions cause the land breezecirculation.La NiñaThe extensive cooling of the central and eastern Pacific Ocean.In Australia (particularly eastern Australia), La Niña events areassociated with increased probability of wetter conditions.LightningThe flash of light from a large electrical spark from or insidea cloud. Lightning can injure people and animals and damage treesand buildings if it reaches the ground.Low latitudesThe southern hemisphere low-latitudes are considered to be theareas of the Earth north of about 30 degrees latitude. ForAustralia, this means the area north of a line from halfway betweenPerth and Geraldton (in Western Australia) to Bourke (in New SouthWales). This part of Australia generally experiences a subtropicalto tropical climate.Low pressureAtmospheric circulations that rotate clockwise in the southernhemisphere. Cyclones are areas of lower pressure and generallyassociated with stronger winds, unsettled conditions, cloudinessand rainfall.Mid latitudesThe areas between about 30 degrees and 55 degrees latitude. ForAustralia, this is the area south of a line from halfway betweenGeraldton and Perth (in Western Australia) to Bourke (in New SouthWales). This part of Australia generally experiences a temperateclimate.MistSimilar to fog, but visibility remains more than akilometre.MJOStands for Madden-Julian Oscillation, also known as the 30-50day wave. This is a periodic enhancement of rainfall over theAustralian tropics, which progresses across tropical latitudesroughly every 30-50 days. Satellite cloud loops and atmosphericpressure changes can signal passage of the wave over Australia,signalling a burst in monsoon (rainfall) activity during thetropical wet season.MonsoonA seasonal wind. The northern Australian monsoon seasongenerally lasts from December to March. It brings cloud and heavyrainfall over northern Australia. The north Australian wet season,October to April, includes the monsoon months but can lastfor several months on either side. Parts of the North Queenslandcoast also have quite heavy rainfall throughout the cooler months.MSLMSL stands for Mean Sea Level. It is necessary to convert thepressure readings to equivalent mean sea level pressures, otherwisethe important horizontal changes in pressure would be overwhelmedby vertical variations simply due to differences in height betweenobserving stations. In this way, a Mean Sea Level Pressure (MSLP)map will then show pressures affected by changing weatherconditions, not because of changing altitude.NitrogenThe most abundant gas in air, comprising 78% by volume. It iscolourless and odourless.OffshoreThe coastal waters zone between 12 and 60 'nautical' miles(about 22 -110 km) from the coast.OxygenThe second most abundant gas in air, comprising 21% by volume.It is a colourless and odourless gas.OzoneOne of the several gases that make up the Earth's atmosphere. Itis the triatomic* form of oxygen and makes up approximately onepart in three million of all of the gases in the atmosphere. If allthe ozone contained in the atmosphere from the ground level up to aheight of 60 km could be assembled at the earth's surface, it wouldcomprise a layer of gas only about 3 millimeters thick, and weighsome 3000 million tonnes. Ozone is toxic at high concentrationsbecause it reacts strongly with other molecules.* Each ozone molecule is made up of three oxygenatoms.PrecipitationAny or all of the forms of water particles, whether liquid (e.g.rain, drizzle) or solid (e.g. hail, snow), that fall from a cloudor group of clouds and reach the ground. (See Drizzle, Rain).Duration of precipitationRain: Individual drops easily identified,puddles form slowly, small streams may flow in gutters.Drizzle: Can be felt on the face but is notvisible. Produces little runoff from roads or roofs. Generallyvisibility is reduced, but not less than 1000 m.Snow: Small sparse flakes. Generallyvisibility is reduced, but not less than 1000 m.Hail: Sparse hailstones of small size, oftenmixed with rain.Rain: Rapidly forming puddles, down pipesflowing freely, some spray visible over hard surface.Drizzle: Window and road surfaces streamingwith moisture. Visibility generally between 400 and 1000 m.Snow: Large numerous flakes and visiblitygenerally between 400-1000 m.Hail: particles numerous enough to whiten theground.Scattered: Irregularly distributed over anarea. Showers which while not widespread, can occur anywhere in anarea. Implies a slightly greater incidence than isolated.Sporadic: scattered or dispersed in respect oflocality or local distribution. Charaterised by occasional orisolated occurrence.Widespread: Occurring extensively throughoutan area.Probable Maximum Flood (PMF)The most severe flood that scientists think is likely to happenat a particular place. The 'worst-case scenario' flood that wouldbe caused if all the worst weather and water conditions happened atonce.Probable Maximum Precipitation (PMP)The most rain that scientists think is likely to fall in acertain time over a certain size storm area at a particular placeat a certain time of year.Probabilities, or Probabilistic ForecastsThese forecasts use percentages, such as 60% (60 percent or 60chances in every 100). This kind of forecast is usually based onhow often something has happened in the past. For instance,if the chance of getting more than average rainfall if certainthings happen is said to be 60%, then in 60 out of 100 of pastyears when things were similar it was higher than usual but in 40out of 100 it was below.High percentages do not mean something will happen, but thatscientists think it is it is likely or probable.RainPrecipitation of liquid usually in drops bigger than 0.5millimetres(mm) falling more steadily than showers.Rain dayA rain day occurs when a daily rainfall of at least 0.2 mm isrecorded.RainfallThe total which has fallen, as measured in a rain gauge.Rainfall amountRainfall amount is the likely amount of rain in millimetres(mm)for the forecast period. Sometimes rain falls in a patchy patternacross an area with some places getting a heavy shower while anarea nearby might miss out completely. On these days the rainfallrange may be quite large, e.g. 5 to 30 mm. When steady rainfall isexpected over a wide area, the range may be smaller, e.g. 10 to15mm.Relative humidityIs a traditional indicator of the air's moisture content. It isthe ratio of the amount of moisture actually in the air to themaximum amount of moisture which the air could hold at the sametemperature. Relative humidity is normally expressed as apercentage and at saturation the relative humidity will be veryclose to 100%. The air can hold more moisture at highertemperatures, hence the relative humidity alone does not give anabsolute measure of moisture content.RidgeA ridge is an elongated area of high pressure. It is indicatedby rounded isobars extending outwards from an anticyclone and hasassociated with it a ridge line. The pressure at a point on theridge is higher than at an adjacent point on either side of theline.Sea and Swell, CombinedCombined sea and swell describes the total height of the sea andthe rise in water of non-breaking waves ('swell') out at sea.Sea and SwellPeak Wave Period: Period in seconds betweenthe swells of the primary swell component. The larger the timedifference, the greater the amount of energy associated with theswells.Primary Swell: Height and direction of theswell with the highest energy component. This is sometimes referredto as the dominant swell.Sea waves: waves generated by the wind blowingat the time, and in the recent past, in the area ofobservation.Secondary Swell: Height and direction of theswell with the second highest energy component.Swell Period: See Peak Wave Period.Swell waves: waves which have travelled intothe area of observation after having been generated by previouswinds in other areas. These waves may travel thousands ofkilometres from their origin before dying away. There may be swellpresent even if the wind is calm and there are no 'sea' waves.Wave period: the average time interval betweenpassages of successive crests (or troughs) of waves.Wave Height: Generally taken as the heightdifference between the wave crest and the preceding trough.Wave Length: The mean horizontal distancebetween successive crests (or troughs) of a wave pattern.Sea breezeA local onshore wind. Cooler air from over the sea flows ontothe shore to replace the warm air rising over the land. On sunnydays the land heats up more quickly, and to a greater extent, thanthe sea. The air in contact with the land warms and expands and theresulting changes in the pressure and temperature differences anddistributions cause the sea breeze circulation. At night, when theland cools more quickly, and to a greater extent, than the sea, thereverse land breeze circulation is set up.ShowersShowers are often short lasting (but may last half an hour) butcan be heavy. They usually begin and end suddenly.SleetGenerally refers to a mixture of rain and snow or falling snowthat is melting into rain.SmogSmog (contraction for 'smoke fog') is a fog in which smoke orother forms of atmospheric pollutant have an important part incausing the fog to thicken, and have unpleasant and dangerousphysiological effects.SnowPrecipitation of ice crystals, most of which are branched(sometimes star shaped).Southern Oscillation Index (SOI)The Southern Oscillation Index (SOI) is calculated from themonthly or seasonal fluctuations in the air pressure differencebetween Tahiti and Darwin.SquallA squall comprises a rather sudden increase of the mean windspeed which lasts for several minutes at least before the mean windreturns to near its previous value. A squall may include manygusts.Storm Force Wind WarningA Storm Force Wind Warning is a statement which warns of windsaveraging from 48 knots and up to 63 knots in coastal waters andhigh seas areas.StratosphereLayer of the atmosphere between about 10 and 50 kilometres abovethe ground.Stratus cloudLow cloud forming a uniform layer.A Strong Wind WarningA Strong Wind Warning is a statement which warns of windsaveraging from 26 knots and up to 33 knots in coastal waters.SupercellA long-lived intense thunderstorm containing a lot of windmovement. Supercell thunderstorms may produce very large hail,extraordinary wind gusts, powerful tornadoes and heavyrainfall.Synoptic chartChart showing lines of equal pressure (isobars), corrected tomean sea level (MSL), over a broad area (eg Australia). Based onthe synoptic observations taken simultaneously every 3 hours byweather observers and Automatic Weather Stations acrossAustralia.Synoptic scaleA horizontal length scale that corresponds to the size of thelarge-scale features of the lower atmosphere (ie the highs and lowsover mid-latitude regions).Stratus cloudLow cloud in a layer or blanket. Stratus clouds may bring verylight rain or snow. A cloudy day usually has a sky filled withstratus clouds hiding the sun.Sea mile, nautical mileA measure at sea equal to about 1.8 kilometres.Severe weather warningSevere Weather Warnings are issued for:Abnormally high tides (or storm tides) expected to be higherthan usual high tide levelsUnusually large surf waves expected to cause dangerousconditions on the coast Southern Oscillation Index (SOI)The Southern Oscillation Index (SOI) is a measure of changes inthe difference in measured air pressure between Tahiti and Darwin.Because of good records about how this has related to our rainfallin past seasons, we can use it to tell what Queensland's likelyrainfall will be in the coming months.Strong wind warningA Strong Wind Warning is a statement which warns of windsaveraging from 26 knots and up to 33 knots (or about 45 to 60kph) in coastal waters. It is usually given by local or stategovernment agencies.Storm surgeA storm surge is a rise above the normal water level along ashore. In tropical areas, storm surges are caused by tropicalcyclones as they come ashore. In a storm surge the water levelrises above normal high tide levels, causing flooding on shore. Theheight of the water and the speed it rises depend on the strengthof the cyclone and shape of the waterfront, among other things.Temperature inversionA temperature inversion occurs when the temperature of airincreases with increasing height. Generally the temperaturedecreases with height in the lower atmosphere, called thetroposphere. Low-level inversions generally form on clear calmnights due to cooling of the ground through loss of heat byradiation. The warm air on the ground is replaced by cooler air atthe surface resulting in a temperature inversion. The inversioncreates a boundary layer that restricts vertical motion and mixingof air between the two air masses either side. Low-level inversionsact like a lid to trap pollutants resulting in smog over ourcities.ThunderstormA storm with sudden electrical discharges which make a flash oflight (lightning) and a loud rumbling sound (thunder).Thunderstorms usually, but not always, bring rain. They usuallyonly last a short time and hit a small area.TornadoA whirlwind or mass of circling air with high wind speeds at itscentre.Trade windsEast to southeasterly winds (in the southern hemisphere) whichaffect tropical and subtropical regions, including the northernareas of Australia. During the monsoon season in northernAustralia, the easterly trade winds are replaced by moistnorthwesterly (monsoonal) winds from the Indian Ocean and southernAsian ocean waters. As mentioned above, the trade winds in thesouthern hemisphere are east to southeasterly in direction. In thenorthern hemisphere however, the trade winds are east tonortheasterly in direction. It means that in both hemispheres, theytend to blow from the east to the west and towards the equator.Sometimes the trade winds will just be called "easterly" to avoidhaving to specify the hemisphere.Tropical cyclonesA tropical cyclone is an intense low pressure system which formsover warm ocean waters in Queensland, The Northern Territory andWestern Australia.A tropical cyclone usually brings strong winds and extremelyheavy rain. It can also bring unusually high sea levels (stormsurges) in areas near the coast.A tropical cyclone can cause widespread damage as a result ofthe strong wind, flooding (caused by either heavy rainfall or oceanstorm surges).It can cause landslides in hilly areas as a result ofheavy rainfall and saturated soil.If there are winds above 117 km/h (63 knots) it will becalled a severe tropical cyclone.(NOTE: A tropical cyclone may also be known (in other parts ofthe world) as a tropical storm. In the north western Pacific severetropical cyclones are known as 'typhoons' and in the northeastPacific and Atlantic/Caribbean they are called 'hurricanes'.)Tropical stormTerm used in the northern hemisphere for a tropical cyclone.TroughA trough of low pressure is an elongated area where atmosphericpressure is low relative to its immediate surroundings. A trough oflow pressure is sometimes indicated on the synoptic chart by acentre line or trough line denoted by a dashed line e.g. - - - - -.The trough line often extends outward from a low pressure centre,or an enclosed area of relatively low pressure. When moving acrossa trough from one side of a trough line to another, atmosphericpressure decreases as you approach the trough line. The atmosphericpressure increases again after you cross the trough line and moveaway. A change in wind direction will generally be observed as youcross from one side of the trough to the other. Compare with thedefinition for a Ridge and a Low.TyphoonTerm used in the northwestern Pacific for a tropical cyclonewith maximum winds above 117 km/h (63 knots).Temperature Celsius temperature scaleTemperature scale (sometimes called 'centigrade'). Water freezesat zero degrees Celsius (0 degrees C) and water boilsat 100 degrees Celsius (100 degrees C).Fahrenheit temperature scale. To work out a temperature indegrees Fahrenheit (degrees F), multiply the temperature in degreesC by 1.8 and add 32. E.g. 10 degrees C x 1.8 = 18 + 32 = 50.So 10 degrees C is the same as 50 degrees F.TsunamiThe name Tsunami is used to describe a series of wavestravelling across the ocean. These waves can measure up to hundredsof kilometres between wave crests in the deep ocean. They are veryfast moving, and unlike normal waves, affect the movement of thewater all the way to the sea floor. They tend to get higher as theyget closer to land and, if high enough when they reach the land,can travel far inland and cause very serious damage.Earthquakes are one of the things that cause tsunami. Theycan also be caused by underwater landslides, volcanoes, landslipping into the ocean, meteors, or even the weather when theatmospheric pressure changes very rapidly. The most common cause oftsunami is an under sea earthquake with a sudden change in asection of the earth's crust under or near the ocean. This rise orfall in sea level makes a tsunami wave.Ultraviolet radiationElectromagnetic radiation with wavelengths shorter than visiblelight, but longer than x-rays. Exposure to too much UV radiationcan cause skin cancer.UpdraughtUpward moving current of air of small dimensions. A rapidlymoving vertical wind as found in thunderstorms.VirgaPrecipitation that evaporates before it reaches the ground.VortexRotating mass of air or water, such as water going down a plughole.Water ResourcesWater available, or capable of being made available, for use insufficient quantity and quality at a location and over a period oftime appropriate for an identifiable demand.Water Resources AssessmentDetermination of the sources, extent, dependability and qualityof water resources for their utilisation and control.Water vapour pressureThe atmospheric pressure which is exerted by water vapour (waterin its gaseous state). It is one way of measuring the humidity ofthe air. At a given temperature, an increase of water vapour in theair corresponds to an increase in the humidity of the air. Watervapour is supplied to the atmosphere by evaporation of water fromoceans, lakes, wet land surfaces or from vegetation(transpiration). Water vapour absorbs the Sun's radiation. As aresult, the sunlight received at the Earth's surface will be moreintense in a drier atmosphere.Wet bulb temperatureWet-bulb temperature is measured using a standardmercury-in-glass thermometer, with the thermometer bulb wrapped inmuslin, which is kept wet. The evaporation of water from thethermometer has a cooling effect, so the temperature indicated bythe wet bulb thermometer is less than the temperature indicated bya dry-bulb (normal, unmodified) thermometer. The rate ofevaporation from the wet-bulb thermometer depends on the humidityof the air - evaporation is slower when the air is already full ofwater vapour For this reason, the difference in the temperaturesindicated by the two thermometers gives a measure of atmospherichumidity.WindUsually only one wind speed is given in a weather forecast,unless it is expected to be very gusty. For instance, fresh, gustysouthwest winds means that wind speed will generally be between 17and 21 knots (or about 30 to 38 kph) and the mean winddirection will be from the southwest, but that there will also bemuch stronger gusts.Squall: A sudden strong wind that rises up and may blow hard anumber of times before it dies down.Surface Wind: wind speed and direction measured at 10 metresabove the earth's surface. The surface wind is what causes waves onthe ocean. Large swells can be caused by strong winds in intensestorms.1. Component of atmospheric circulation along a line oflatitude, towards the east or west.2. Atmospheric circulation along, or approximately along,parallels of latitude.

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