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Weather

Weather. Meteorology . Study of atmospheric phenomena Weather – Current state of the atmosphere. Air Density. Like most substances, cold air is more dense than warm air Cold air will sink, hot air will rise. Air Masses.

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Weather

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  1. Weather

  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

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

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

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

  8. 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

  9. 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

  10. 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

  11. Using Weather Models

  12. Using Weather Models

  13. Using Weather Models

  14. Acid precipitation • Acid rain, acid fog, acid snow • Reaction of pollutants like SO2 and NO with water, oxygen, and oxidants to form acids that fall to surface in precipitation: • sulfuric acid (H2SO4) • nitric acid (HNO3)

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

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

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

  18. 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

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

  20. Severe Storms

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

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

  23. Development • Precipitation will stay uplifted until heavier than uplift force

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

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

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

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

  28. 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

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

  30. Hurricane Intensity • Saffir-Simpson Hurricane Scale

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