Transcript Chapter 1
Chapter 1 Physical Meteorology Introduction We all have some skills when it comes to the weather What will be lacking is both scope and depth This chapter looks at what you probably know about the weather Class Exercise 1.1 Conduct a class discussion about the sources of weather information and the types of information that we receive Complete the important terms list found on Page 12 of these notes Meteorology vs Climatology What is meteorology? Meteorology is the study of the weather What is climatology? Climatology is the study of weather averages The concept of scales There are three common scales used in meteorology; Global (macro) Synoptic Local (meso) (micro) There are many more scales used in meteorology The scales of the weather Meteorology & Society The history First written discussion by Greeks Bloomed during Industrial Revolution Great advances were made during the wars of the 20th Century due to wars After WW2, computers changed the volume of data processed This led to the Numerical Weather Prediction methods used today Meteorology in the news We have all watched TV and seen the following; Storms and hail damage Flood Cyclones, tornadoes and hurricanes Drought Snow and blizzards Class Exercise 1.2 Weather phenomena Country/Landmass or Region Monsoon East asia/Asutralasia Doldrums Equatorial regions Roaring forties South Western Australia Southerly buster South Eastern Australia Cyclones Tornadoes Trade winds Typhoons Hurricanes Northern Australia Mainly Northern USA 30° Latitude North Eastern Pacific Southern USA, Mexico area The social importance of weather It really isn’t difficult to see why meteorology is socially important. If you are a surfer for example, then you will know what weather brings good surf, and bad. The same applies if you are a farmer, or even an office worker, but for different reasons. The social importance of weather Government based meteorological, hydrological and related information and services make important contributions for achieving an increased social awareness of the importance of meteorology The social importance of weather Weather and climate information and forecasts contribute to the development of well managed and less vulnerable agriculture, combating droughts (and subsequent drought proofing), desertification, better air quality, reduced health problems and better quality of everyday life, Exercise 1.3 Occupation Farmer Surfer Salesperson Sewer worker Environmental technician Meteorologist Politician Pilot Ecologist Reason for observation Why do you need to know about meteorology? This is the age of environmental legislation and regulation (i.e. laws). To monitor air pollution properly, we need to now about where that pollution came from, and where that pollution is going (amongst many other things), RESULT? We need to know about meteorology! Meteorology and Climatology in Australia So who runs meteorology and climatology in Australia? The Bureau of Meteorology (BoM, or ‘the Bureau’). Although legislated in 1906, the Bureau started operation in 1908, and has grown in conjunction with other national meteorological institutions overseas into a world leader in meteorological services. Meteorology and Climatology in Australia The BoM is a member of the World Meteorological Organisation (WMO). The WMO started operations in 1950, with the BoM being a foundation member. The WMO has allowed for otherwise impossible work to be done. The WMO cornerstone is the Global Weather Experiment in 1979, which is the largest single scientific experiment ever undertaken. Meteorology and Climatology in Australia The BoM, and the WMO are only two of a plethora of international organisations that work with weather and weather related information (such as geographers and oceanographers) to provide the world with meteorological information and data. The Australian Climate It is impossible to ‘average’ Australia’s climate There are many different climate ‘zones’, and each has its own average climate. Over the years there have been numerous attempts to define different climate zones, globally, and in Australia. The Australian Climate The BoM currently (2005) use the Koppen (Koeppen) system of classification, of which there are six climate zones; Equatorial Tropical Subtropical Desert Grassland Temperate The Australian Climate The north of Australia lies close to the equator, It also lies in the equatorial monsoonal region (monsoon is rain that accompanies biannual wind changes in the South-East Asia region) So this area exhibits hot dry winters with hot wet summers. The Australian Climate Australia's southern coastline is what makes the southern Australian climate. The other southern hemisphere continents do not have long coastlines parallel to Antarctica. The southern African coastline is more rounded, and is further north. While the tip of South America comes to within 1000km of the Palmer Peninsula on Antarctica, the long spine of the Andes means that there is no contrasting hot interior. The Australian Climate To the south of the Australian coast, the Southern Ocean extends 3000km to the Antarctic continent. From there, outbreaks of very cold polar air move northwards, warming somewhat as they pass over the ocean which results in the ‘cold fronts’ you see on the TV weather segments. The Australian Climate Inland from the southern coast, a large proportion of the country is arid or semi-arid, with low rainfall and very hot summers. This is due to a process called mid latitude desertification, and air that travels from the hot interior to the coast meets the cold air from Antarctica, giving southern Australia highly variable weather. Exercise 1.4 Go to http://www.bom.gov.au/climate/environ/other/kpn_gro up.shtml and print the map. On the map, indicate the reasons why you think the climate zones exist where they do. Physical Meteorology Physically, we feel the weather. We use all of our senses to gauge what the day will bring, and what we should do about it. Our senses are (and were) the first meteorological instruments that we had, as we could see and hear a storm coming, and we could taste and smell the rain or dust, and we could feel wet or dry, or simply uncomfortable. Emotionally the weather makes us happy or sad, anything else is up to you Physical Meteorology Of all the senses, it is sight that has given us the science. We have found ways of taking visual information and using that information to provide us with clues as to what the weather will be like tomorrow, i.e. the weather forecast – the holy grail of meteorology! And the information we collect, we put onto a visual device called a weather map. If we look at maps over time, we start to see trends in the weather, which gives us confidence to say what definitely will, and definitely will not happen tomorrow The Weather Map The weather map would probably be the most looked upon, and the most misunderstood map in the world. A weather map has a enormous amount of information on it, with most of this information being symbolic in nature, which of course, needs to be explained (in full, later in these notes). Class Exercise 1.5 Look at the weather map below, and hold a class discussion describing as many of the features on the map as possible. This is designed to test what you already know - you are yet to be taught how to read a weather map properly. Class Exercise 1.5 Exercise 1.5 You may have been able to describe the following; Isobars Pressure values High (H) and low (L) pressure systems Wind direction and speed Rainfall At least that the country is Australia! The Weather Map Hopefully, by the end of this course, you will have the skills to not only read a weather map, but you will be able to predict from the information on the map what is going to happen over the next few days. Physical components of the atmosphere Dusts, particulates and pollution Is dust a nuisance or essential to weather? Without solid material, (termed particulate), precipitation would not form as the water (or ice) needs something to ‘stick’ onto (termed a nucleus). Dust can be natural or pollution from human activites Physical components of the atmosphere Two very important terms arise from a discussion of dusts and the like Aerosol refers only to those liquid and solid particles that are suspended in the air such as acid, dust, and smoke particles Pollutant refers to any substance (solid, liquid, or gas) that contaminates the atmosphere and can potentially cause adverse effects to our health and environment Physical components of the atmosphere Clouds Clouds are classified according to their height in the sky low (from the earth's surface to 2.5 km) middle high (2.5 to 6 km) (above 6 km), and According to their shape, colour and the weather they bring. Physical components of the atmosphere In Australia (and generally worldwide), there are ten major cloud types Cirrus Cirrocumulus Cirrostratus Altocumulus Altostratus Nimbostratus Stratocumulus Stratus Cumulus Cumulonimbus Exercise 1.6 Go to http://www.bom.gov.au/info/clouds For each of the clouds mentioned above, state whether they are low medium or high Provide a description of the weather they bring (if any) Physical components of the atmosphere Fog What exactly is fog? Simply put, fog is a special type of stratus cloud, of which there are two main types; Radiation fog Advection fog Other types of fog include; Steam fog Maritime fog Hill fog Physical components of the atmosphere fog – occurs when moist air above the ground cools faster than air higher above Radiation Steam fog – occurs when cold air moves over warm water fog – is special as it can occur when air moisture is very low due to slat particles in the air Maritime fog – occurs when warm humid air travels over a colder land Advection Hill fog – occurs is actually a low lying cloud on a hill Physical components of the atmosphere Haze Remember the concept of aerosols we mentioned earlier? Well some aerosols, such as salt and certain dust particles, have an attraction to water (termed hydrophilic). For this reason, the relative humidity does not have to reach 100% before water vapour condenses onto them. At a relative humidity of about 70%, these aerosols start to attract water vapour and dissolve, forming a tiny solution droplet much smaller than a cloud droplet. Physical components of the atmosphere High concentrations of these solution particles in the air form what we call haze. Haze does not qualify as either a cloud or fog, but greatly reduces visibility in the air both near the ground and aloft. Decreasing visual air quality as a result of haze is an indicator of the increasing concentrations of pollutants in our air Physical components of the atmosphere Precipitation Rather than insult you, we shall just remind you that the term precipitation covers rain, hail, snow, and sleet Lastly, it is this (and temperature and wind) that we look out for most in the weather segment on the news. Physical components of the atmosphere Wind Wind is mentioned here due to its obvious importance and effects. Firstly, it is one mechanism by which all of the other physical components of the atmosphere are transported (such as clouds, fog and dusts), To plant the seed for you that wind measurements are crucial for environmental technicians due to its direct influence on noise and air pollution analysis