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Meteorology

Meteorology. Subject: ADVANCED AERONAUTICS Subject Code: AER 200 Faculty: Brian CARLICK Date: January 11, 2006. COMPOSITION AND STRUCTURE OF THE ATMOSPHERE PRESSURE STANDARD ATMOSPHERE TEMPERATURE MOISTURE STABILITY WINDS

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Meteorology

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  1. Meteorology • Subject: ADVANCED AERONAUTICS Subject Code: AER 200 • Faculty: Brian CARLICK Date: January 11, 2006

  2. COMPOSITION AND STRUCTURE OF THE ATMOSPHERE • PRESSURE • STANDARD ATMOSPHERE • TEMPERATURE • MOISTURE • STABILITY • WINDS • CLOUDS

  3. Atmosphere Compositionand Properties Atmosphere has weight • 14.7 psi @ sea level or 1013.2 mb • Half of it is below 18,000 feet • No well defined upper surface but satellite drag data indicates some air at 1,000 miles • Gases each contribute to atmospheric pressure • Water vapour usually less than 1% but can be 3.5%

  4. Properties / Structure of the Atmosphere • Water Vapor is essential for weather • found in lower levels • responsible for clouds and precipitation • H2O vapour (10) is lighter than O2(16) or N2(14) • H2O content varies hour to hour, day to day, by season and by latitude • Water content changes depending on temp & pressure

  5. Properties / Structure of the Atmosphere • Air is a fluid • Mobility, expansion & compression • Lifting agents can be Frontal, Thermal, Orographic, Mechanical • Rising air is subjected to reducing pressure and expands and cools

  6. As air expands (rising) pressure decreases and temperature decreases 15 oC 20 oC As air compresses (sinks) pressure increases andtemperature increases 25 oC

  7. Vertical Structure THERMOSPHERE 3000 ° C @700km IONOSPHERE MESOPAUSE MESOSPHERE STRATOPAUSE STRATOSPHERE TROPOPAUSE TROPOSPHERE SEA LEVEL

  8. KM 120 110 100 90 80 70 60 50 40 30 20 10 0 0 10 20 30 40 50 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 Vertical Structure -108 °C 275,000 feet Temperature distribution -2.5 °C 165,000 feet -56.5 °C 36,089 feet

  9. EXOSPHERE Starts 500 to 800 km up IONOSPHERE 80km to 400km Aurora -108 °C MESOPAUSE -2.5 °C STRATOPAUSE 6 to 30 miles -56.5 °C TROPOPAUSE °C

  10. Humidity and Dew point • Warm air can hold more moisture. • The water vapor a volume of air can hold is governed by its temperature. • Air is said to be saturated when it contains the maximum amount of water it can hold at that temperature. • Dew point - the temperature to which unsaturated air must be cooled to become saturated. • Relative Humidity - the ratio of actual water vapor present in the air to the amount which that volume of air would hold if saturated. • When air is heated, without adding water, the relative humidity decreases.

  11. The Thermosphere is important because it contains properties of mobility, and it has a capacity for expansion and contraction. • Allows movement under it, ie. lows and highs • The Thermosphere also contains the Ionosphere, which can affect radio waves. • Jet Streams are found at the top of the troposphere, much lower than the thermosphere. They are higher at the equator and lower at the poles. They descend in winter and rise in summer.

  12. Pressure: • Is important for determining altitude • Distribution determines winds (mobility). • Is Force exerted by the air at that altitude Area • Station pressure: is the actual atmospheric pressure at the elevation of the observing station. • MSL: is used to compare the pressures of stations with different elevations.

  13. Pressure, Density & Altimeter settings 14.90 29.92 Eg. Actual pressure Pressure setting 7.40 29.92 34000 feet 14.90 29.92 18000 feet 28.92 29.92 29.42 29.92 29.92 29.92 1000 feet 500 feet Sea level

  14. Defining the Standard Atmosphere • 29.92”Hg (1013.2 mb) @ sea level • 15° C @ sea level • 1.98° C per 1,000 feet • 1”Hg = 1,000 feet (varies with height) • 1 mb = 30 feet • Air is presumed perfectly dry for standard

  15. Low Pressure • Low or Cyclone is rising air • Bad weather, poor visibility • Stratus clouds, light winds • Movement: • Summer: 500 miles / day • Winter: 700 miles / day • Winds: • Above 3000agl: parallel to isobars • Below 3000agl: INTO the low • Consistent day and night temperatures • Low pressure is by comparison to surrounding areas • Counterclockwise rotation in Northern hemisphere

  16. Buys Ballot’s Law • Stand with the wind at your back. • Stick out your left arm. • Your fingers will point to the center of the low pressure area !!!

  17. High Pressure • Anti-cyclone is descending air, compression occurs • Clockwise circulation in Northern hemisphere • Highs fill in Lows • Surface winds blow outwards in a slow spiral • Clear skies predominate • Higher day temperatures, lower night temperatures • Good visibility • Cumulus type clouds • Breezy

  18. Wind • The heating of the earth’s surface is responsible for circulation. The sun heats the earth which then radiates the heat, heating the adjacent air at the surface. • Upper winds flow parallel to isobars, with wind speed determined by the spacing. • Surface winds are slower due to surface friction, and will blow in or out depending on the surrounding pressure.

  19. PRESSURE GRADIENT

  20. HIGHLOW2nd lowTROUGHCOLRIDGE1000 +/-WIND

  21. Gusts and Squalls • Gusts: rapid, irregular fluctuation in velocity and direction. Peak 5 kt higher than 2 minute average • Squalls: longer in duration. 15 kt higher than mean speed and peak for 2 minutes

  22. Land Breeze Wind cooling land water Sea Breeze Wind warming land water

  23. FUNNEL EFFECT

  24. Katabatic (night) Chinooks Anabatic (day) Valley Breezes

  25. KATABATIC WIND

  26. ANABATIC WIND

  27. WIND vs TURBULENCE

  28. STRATUS

  29. CUMULUS

  30. Clouds • Stable vs. Unstable (Horizontal/Vertical) • 2 main types - Stratus vs. Cumulus • Heights of clouds give 4 families - High - Middle - Low - Vertical development

  31. CLOUD CLASSIFICATIONS

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