2. Meteorology Study of atmospheric phenomena Weather – Current state of the atmosphere

3. Air Density Like most substances, cold air is more dense than warm air Cold air will sink, hot air will rise

4. Air Masses Large body of air that takes on characteristics of area it covers (land and water) – Air Mass Modification

6. Wind Systems Jet Streams – High altitude, westerly winds Responsible for most of our weather in our country

8. Pressure Systems Low pressure – air rises Clouds and precipitation High pressure – air sinks and spreads Fair weather

12. Wind caused by movement of air molecules Cool dense air sinks, forces warm, less dense air upward Air Pressure and Wind

13. Fronts Narrow region separating two air masses Cold – cold air displaces warm Warm – warm air displaces cold Stationary – do not displace Occluded – warm squeezed between cold

14. Water in Atmosphere Humidity Amount of water vapor in the air Relative Humidity water vapor in the air compared to how much water vapor the air is capable of holding Warm air holds more moisture

15. Cloud Formation Condensation Nuclei – small particles in atmosphere which water condenses around Millions = cloud Coalescence – droplets collide, become bigger Precipitation – droplets become too big and fall

16. Using Weather Models

19. Acid precipitation Acid rain, acid fog, acid snow Reaction of pollutants like SO 2 and NO with water, oxygen, and oxidants to form acids that fall to surface in precipitation: sulfuric acid (H 2 SO 4 ) nitric acid (HNO 3 )

20. Acid precipitation Acid precipitation is created by reactions in the atmosphere, and can fall many miles from where pollution originated. Figure 11.18

21. Acid precipitation Acidity varies geographically. (Orange = more acidic) Industrialized areas and regions downwind of them suffer most. Figure 11.20

22. Acid precipitation Acid precipitation has killed these conifer trees in the mountains of North Carolina. From The Science behind the Stories

23. Acid precipitation This can be seen in data from New Hampshire’s Hubbard Brook Experimental Forest, where acid rain was first studied. pH has increased (rain has become less acidic) since 1970, but is still much more acidic than normal rain. From The Science behind the Stories

24. Seasonal Weather Why do we have different weather in different seasons? Why do we even have the seasons? What is the cause? Weather? Climate?

27. Thunderstorms Generates lightning and thunder Frequently produce gusty winds, heavy rains, and hail 45,000 a day across the world

28. Development Warm, humid air rises in unstable environment Uplift carries warm, moist air into cooler part of atmosphere

29. Development Precipitation will stay uplifted until heavier than uplift force

30. Development Downdrafts throughout the cloud (cold air) Storm dies

31. Tornadoes Take form of rotating column of air called vortex Uplift turns vortex vertical

33. Tornado Intensity Pressure inside lower than outside Air rushes in to equalize pressure Winds may reach 480 km/h (300 mph)

34. Hurricanes Whirling cyclones that produce winds of at least 119 km/hr U.S. - hurricanes

35. Development Late summer – warm waters to provide heat and moisture Eye wall – center wall that surrounds center of storm Highest winds and heaviest rain fall Warm, moist air rushes up

36. Development Eye – air is descending No precipitation or wind High pressure

38. Hurricane Intensity Saffir-Simpson Hurricane Scale