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Meteorology

Meteorology. 5.06 Turbulence, Visibility, and Fronts References: Air Command Weather Manual Chapters 7, 8, 10 and 11 FTGU pages 133, 138, 140-145, 147, 155 and 156 Aviation Weather Student Guide http://www.tpub.com/content/aviation2/P-303/index.htm.

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Meteorology

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  1. Meteorology 5.06 Turbulence, Visibility, and Fronts References: Air Command Weather Manual Chapters 7, 8, 10 and 11 FTGU pages 133, 138, 140-145, 147, 155 and 156 Aviation Weather Student Guide http://www.tpub.com/content/aviation2/P-303/index.htm

  2. 5.06 Turbulence, Visibility, and Fronts • MTPs: • Types of Turbulence • Wind Shear • Visibility Obstructions • Definition of a Front • Front Formation • Warm Front • Cold Front • Fronts on Maps

  3. Types of Turbulence • Convection Turbulence Thermal Turbulence • Hot sunny days - sun heats the earth’s surface unevenly Isolated convection currents cause turbulence

  4. Types of Turbulence 2. Mechanical Turbulence Also known as “eddies” • Friction between air and ground • Irregular terrain and man-made obstacles cause severe eddies. • http://www.youtube.com/watch?v=vQHXIHpvcvU

  5. Types of Turbulence 3. Orographic turbulence • Known as mountain wave • Can be expected on the windward side and over the crests of mountains, along the downward slope • Avoid rotor cloud and strong downdraft on the leeward side of mountain

  6. Wind Shear 4. Wind Shear • Any marked change in wind speed and direction with height that produces local areas of turbulence • When changes are large, quite severe turbulence can be expected • Low level wind shear occurs as a result of gust fronts and downbursts • Associated with thunderstorms

  7. Wind Shear Inversions • Overnight cooling creates temperature inversion a few hundred feet above ground that can produce significant wind shear • Can also form where cold air trapped in low lying areas (ex. valleys) as cold air denser than warm air • At night this air will “flow” into low lying areas

  8. Confirmation 1. Wind shear is a sudden change in the wind’s ____________ and/or ___________. 2. ________________ is the condition when the temperature increases with altitude. 3. _____________ causes turbulence due to uneven heating of the ground.

  9. Visibility Obstructions • Haze • Very small water droplets, dust or salt particles • Cannot be felt or individually seen with naked eye • Uniform veil, restricts visibility • Only a problem in stable air.

  10. Visibility Obstructions • Smoke • Created by industrial pollutants, vehicle exhaust in urban/industrial areas – thick blanket of haze severely restricting visibility • Worse when flying towards the sun • Forest fires can also contribute in more rural areas.

  11. Visibility Obstructions • Smog • Combination of smoke and fog • Has a yellow colour to it due the pollution mixed in with it • Often occurs with an inversion • Type of air pollution derived from vehicular emission from internal combustion engines and industrial fumes • Fumes react in the atmosphere with sunlight to form secondary pollutants

  12. Confirmation • 1. What are some of the visibility obstructions a pilot can face? • 2. How is thermal turbulence created? • 3. How is an inversion formed? • 4. Which part of a mountain would see the worst turbulence?

  13. Definition of a Front • Definition: • FTGU: Transition zone between two air masses • What’s happening at a front? • Large change of temperature within a relatively short distance of 50-100 miles in the zone between air masses • The interaction zone between the air masses is responsible for weather changes Front

  14. Front Formation • Requirements: • a cold air mass and a warm air mass lying adjacent • mixing action

  15. Front Formation • Air Mass: • A large section of the troposphere with uniform properties of temperature and moisture • May be several thousand miles across

  16. Warm Front • A warm front is the retreating edge of a cold air mass • Warm air advances and overruns retreating cold air • Warm air rises since it is less dense than cold air • Usually moves slower than a cold front • Long gentle frontal slope. Simulation http://www.phschool.com/atschool/phsciexp/active_art/weather_fronts/

  17. Warm Front Warm front weather • Warm air mass pushes moisture up the slope, causing cloud and precipitation • Overrunning, moisture content and stability of warm air determines severity of weather • If the warm air is unstable, thunderstorms may be embedded

  18. Warm Front

  19. Warm Front • Indication of Approaching Warm Front: • CCANS • Cirrus • Cirrostratus • Altostratus • Nimbostratus • Stratus

  20. Cold Front • A cold front is the leading edge of an advancing cold air mass • Cold air undercuts the warm air • Rising warm air expands and cools • Cumulus cloud

  21. Cold Front • Slope can be very steep • Weather severity determined by moisture content and stability of the warm air mass Simulation http://www.phschool.com/atschool/phsciexp/active_art/weather_fronts/

  22. Cold Front

  23. Cold Front • Temperature • May drop sharply after front passes • Usually drops gradually as air behind is warmed by the ground • Pressure • Decrease, followed by a marked rise after frontal passage

  24. Warm and Cold Front

  25. Fronts on Maps • Red = Warm • Blue = Cold

  26. Confirmation 1. Label where the cold front and where the warm front is. 2. Label what clouds are associated with the fronts 3. Draw an arrow to show which direction the front is moving

  27. Confirmation • What weather is associated with a cold front? • What weather is associated with a warm front?

  28. Severe Frontal Weather

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