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Weather,_Climate,_&amp;_Society_F10_Lect3

# Weather,_Climate,_&amp;_Society_F10_Lect3 - Weather...

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Weather, Climate, and Society Fall 2010, Lecture 3 1

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Weather Day to day record Temperature Precipitation Time scale is short One week typical Two weeks maximum 2
Weather Forecasting Weather results from a chaotic system No mathematical tools which can completely predict the behavior of chaotic system exist The longer the term of the forecast the less “skill” it exhibits 3

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Forecast skill Skill refers to the ability of the forecast to exceed chance variation Suppose that on a given day in Boca Raton the long term average of rain on a particular day is 40% A forecast of rain or no rain one week in advance of that date that is correct 40% of the time shows no skill A forecast that is correct 60% definitely exhibits some skill 4
Skill continued Forecasts one day in advance often show high skill levels As the forecast period lengthens, errors in the forecast multiply Eventually the forecast is entirely erroneous 5

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Long-term Averages Long-term weather records can be used to compute averages, which do have validity Example: we may the average temperature and amount of rainfall by individual months Data like this show that there is much more precipitation in South Florida between late May and November than for the remainder of the year We can also find out the average temperature in any given month - such data show that there is considerable variation from year to year 6
Climate Climate encompasses the statistics of meteorological elements in a given region over long periods of time Meteorological elements may include: Temperature Humidity Atmospheric pressure Wind velocity (speed and direction) Rainfall rates and total amounts 7

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Temporal Scale of Climate Ranges from decades to far longer periods For the shorter term periods, we may have accurate measurements, over periods up to 150 years, and sometimes longer Of course, modern instrumentation means that modern data are generally superior to older data 8
Climate Change A change in the statistical distribution of weather over a period of time Ranges from decades to millions of years Can be a change in the average weather or a change in the distribution of weather events around an average (for example, greater or fewer extreme weather events) May be limited to a specific region, or may occur across the whole Earth 9

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Long-term Climates Climate data for periods exceeding that of written records requires other sources of data Geologists and geochemists Coaxing information out of natural objects o Glacial ice o Stalagmites o Lake and marine sediment cores, etc. o Tree rings o Boreholes 10
Palynology Study of contemporary and fossil palynomorphs, including pollen Palynomorph is a geological term used to describe a particle of a size between five and 500 micrometers, found in rock deposits (sedimentary rocks) and composed of organic material

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