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How can weather be predicted
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  • 1. How can weatherbe predicted?Grade 4
  • 2. Have you everwondered why theweather changes?
  • 3. When a large body of air movesit causes weather changes.Air massLarge body of air.
  • 4. Air massescan be:Hot air mass Cold air massAll of an air mass has the sametemperature and same amount ofmoisture level (amount of water inthe air).
  • 5. Blue arrows are cold air massesRed arrows are hot air masses
  • 6. Temperature and moisture level depend onwhere the air masses where formed.Dry airmassFormedover landWet air massFormed overoceans orseasHot airmassCome fromthe southCold airmassCome fromthe north
  • 7. Type of weather caused by different airmasses:Cold, dryair massesCoolweather, withlittle or noprecipitationWarm, moistair massesLot ofprecipitationWarm, dryair massesWarmweather +little or noprecipitationCold, Wetair massesSnow
  • 8. Air massesStay separateWhy?Because warm air is lighter than coldair.So, warm air masses are pushedupward and cold air masses sink.
  • 9. Air massesmoveThe border between one air mass andthe other is called a front.
  • 10. Air frontscan be:HotfrontColdFrontStationaryfront
  • 11. 1) Cold FrontCold air moves under warm air.Warm air mass moves up and cools down.Water vapor condenses and moves up.It might rain or thunderstorms develop alongthe frontAs the cold air mass moves forward theweather becomes cooler.
  • 12. 2) Warm FrontWarm air moves slides over cold air.Warm fronts moves slowly.Steady rain instead of thunderstorms.Warm fronts are followed by clear, warmweather.
  • 13. 3) Stationary frontA front that stays in one place for many daysHappens when two air masses do not haveenough energy to move.Steady rain instead of thunderstorms.Weather along the stationary front is oftencloudy and wetThis kind of front can leave inches of snow orcause flooding.
  • 14. Types ofclouds
  • 15. Stratus cloudsOccuralongwarmfronts
  • 16. Nimbostratus cloudsBringslight rainor snow
  • 17. Cumulus cloudsCommononclear, warm days.
  • 18. Cumulonimbus clouds(Thunderstorm clouds)Developsfromcumulusclouds.
  • 19. Cirrus cloudsIndicatecool, fairweather.
  • 20. Weathermaps
  • 21. Weather maps helpyou know what theweather is like in anarea.Weather maps use symbols toshow the weather.
  • 22. Weathermapsymbols
  • 23. Many weather maps show temperatures.The temperature can be:Written on a map. Shown using colors.Red (Very hot)Orange (Warm)Green (Cool)Yellow (mild)Blue (Very cold)
  • 24. L(Low air pressure)H(High air pressure)
  • 25. In the USA the temperature unit is Fahrenheit (°F)
  • 26. Read thefollowingweather maps.
  • 27. Where does all the informationon a weather map come form?Weather stations
  • 28. Some Weather instruments1) BarometerMeasures air pressure
  • 29. 2) ThermometerMeasures air temperature
  • 30. 3) Wind vaneShows which direction wind is moving
  • 31. 4) AnemometerMeasures wind speed
  • 32. 5) Rain gaugeMeasures amount of precipitation