Chapter 12 Meteorology

1. Chapter 12 Meteorology

2. Meteorology – study of the atmosphere Weather – current state of the atmosphere – short term Climate – long term variations in weather for a particular region Air mass – large body of air that takes on characteristics of area where formed Air Mass Modification – air mass takes on new characteristics of new surface it moves over

3. 6 types of atmospheric meteors • Clouds • Raindrops • Snowflakes • Fog • Dust • Rainbows

4. Examples of Hydrometeors • fog, rain, snow (Cloud droplets that contain water in any form)

5. Examples of lithometeors • Smoke, haze, dust (solid dust or sand particles)

6. Examples of Electrometeors • Thunder and lightning (visible/audio manifestations)

7. Weather vs Climate • Weather is current and climate is long term • Weather is the current state of the atmosphere • Climate describes weather patterns

8. Why polar regions are never warm? The suns rays strike the poles at low angles – energy is spread over a larger region

9. Everything we consider as weather is due to constant redistribution of heat energy Source Region – regions where air masses form

10. 7 types of air masses A – Arctic cP – Continental Polar cT – Continental Tropical mP – Maritime Polar (Pacific) mP – Maritime Polar (Atlantic) mT – Maritime Tropical (Pacific) mT – Maritime Tropical (Atlantic)

12. Copy Figure 12-3 and label the major air masses and the direction of air flow. Include table 12-1 that lists the stability of the source regions

13. Section 12.2 Weather Systems

14. Coriolis effect – air deflected to right N. hemisphere and left in South due to rotation of earth Trade winds – 30 degree N/S latitudes air sinks, warms and moves toward equator in westerly direction Prevailing westerlies – 30 – 60 degrees N & S latitude opposite of trade winds, move towards pole eastwardly

15. Jet stream – narrow bands of fast moving high altitude westerly winds, slows at speeds up to 185 km/h and 10.7 – 12.2 km high Front – narrow region separating 2 air masses of different densities

16. What does the earth’s rotation cause? Coriolis effect Heat imbalance create wind systems that move cold air to warm air and warm air to cold air

17. 3 basic wind systems Trade winds Prevailing westerlies Polar easterlies

18. Label the wind systems

19. Differences in temperature and pressure Causes wind Jet stream separates polar easterlies from the prevailing westerlies

20. Jet stream Subtropical jet stream separates trade winds and prevailing westerlies Jet streams represents difference in pressure and temperature

21. Jet stream Moves air of different temperature from one region to another Density differences is caused by the temperature and salinity of the water

22. Draw 4 types of fronts • Cold Front • Cold air displaces warm air forcing the warm air up • thunderstorms • Warm front • Warm air displaces cold air • Precipitation and cloudiness

23. Draw 4 types of fronts • Stationary Front • 2 air masses meet and neither advance • Heavy rain and clouds • Occluded Front • Cold air mass overtakes a warm front, wedges warm air upward

24. Air Low Pressure High Pressure Air rises Moves counterclockwise in Northern Hemisphere Clouds, precipitation Air sinks Moves clockwise in Northern hemisphere Fair weather

25. Wave cyclone Begins along a stationary front Low pressure system is formed by a wave cyclone

26. Section 12.3 Gathering Weather Data

27. Thermometer – measures temperature • Barometer – measures air pressure • Anemometer – measures wind speed • Hygrometer – measures relative humidity • Ceilometer – measures height of cloud layer and estimate cloud cover • Radiosonde – balloon package that has sensors for weather data • Doppler Effect – change in wave frequency of energy as it moves towards or away observer

28. 4 Atmospheric variables • Temperature • Air pressure • Humidity • Wind

29. 4 instruments used • Thermometer • Barometer • Anemometer • Hygrometer

30. 1700 Sites established for surface data collection • Gathered once every hour • 30,000 meters because weather changes caused by upper atmosphere conditions

31. Radiosonde • Collects Temperature, air pressure, humidity • Very expensive • Radar stands for radio detecting and ranges up to 400 km in diameter

32. Doppler Radars • Doppler radio plots the speed of wind • Other weather systems don’t measure the wind speed • Doppler Effect – change in frequency as sound/light moves toward/away from the observer

33. Satellites • Track clouds (not precipitation) • Infrared imagery detects difference in thermal energy (cloud cover or surface temp) • Tells us about the temperature of clouds at different levels of the atmosphere • Useful in detecting strong thunderstorms

34. Section 12-4 Weather Analysis

35. Station Model – record of weather data same site/specific time • Isopleth – lines that connect parts of equal value • Digital Forecast – forecast that relies on numerical data • Analog forecast – comparing current weather patterns to past events

36. Meteorological Symbols • Represent types of weather data in a station model • Station models are useful because its large amount of data in a small space and gives meteorologists a uniform way of communicating data

37. Isopleths • Values represent pressure and temperature • Isobars lines of equal pressure • Isotherms lines of equal temperature

38. Isobars • That close together indicate large pressure differences in a small area • Strong winds are caused by large pressure difference in small areas

39. Isobars • Far apart – small difference in pressure • Light winds • Also indicate high and low pressure systems • Temperature gradients = frontal systems

40. Meteorologists must understand current weather conditions before they can move on to forecasting the weather

41. The atmosphere behaves like a fluid

42. Drawbacks for analog forecasts • Past event must mirror current conditions • Forecast uncertainty increases with time

43. Digital Forecasting • Digital forecast is the most accurate – the more data collected the more accurate it is

44. 3 changes monitored during long term forecast • Changes in atmosphere • Ocean currents • Solar activity