Cadet Phase I & II Aerospace Dimensions Air Environment (Module 3) by hcj


									                          Cadet Phase I & II
                Aerospace Dimensions
                  Air Environment (Module 3)

   Session 1:
     Chapter 1 ‘Air Circulation’
     Chapter 2 ‘Weather Elements’
   Session 2:
     Chapter 3 ‘Moisture and Clouds’
     Chapter 4 ‘Weather Systems and Changes’

        (ONLY for all Cadets that have not yet passed corresponding AE test, and Cadet Mentors)

                             Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing    1
                      Air Circulation
   Radiation - a method of Heat Transfer
     This is the ONLY way heat can travel in a vacuum, and
      is therefore how the Sun heats the Earth
     About 65% of the sun’s energy gets past the clouds
         15% is absorbed by the atmosphere, the remaining 50% is
         absorbed at the Earth’s surface
     Heat and Pressure differences in the atmosphere,
      caused by Solar Heating are what causes weather
     Heating and Cooling of the atmosphere also
      evaporates/condenses water vapor, causing clouds,
      rain, snow, and hail
     Temperature and Pressure Changes also affect air
      density, which directly affects LIFT
      (remember Module 1?)
                     Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   2
                         Air Circulation
   Rotation and Revolution
     The Earth Revolves around the sun once every 365
      days (approx.)
     The Earth also Rotates, tilted at an angle of 23.5°
        Revolution and Rotation together cause the seasons, and
          different weather patterns at different latitudes
         Tilted towards the sun = long day
         Tilted away from the sun = short day
         Sun tracking along equator = day/night of equal length
            – Autumnal Equinox: Equal length Day/Night (Fall - Sept 22/23)
            – Vernal Equinox: Equal length Day/Night (Spring - Mar 21/22)
            – Summer Solstice: Longest Day (June 21/22)
            – Winter Solstice: Shortest Day (Dec 21/22)

                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   3
                          Air Circulation
   Coriolis effect: Since the Earth is rotating Counter-Clockwise,
    anything travelling from North to South will be deflected WEST of
    the intended destination, if the fact that the earth is moving under
    them, is not accounted for
   Circulation
       Uneven heating (e.g. equator and poles) causes pressure
        differences, which result in movement of air
       Air is heated at the equator,
        rises, then heads north or south,
        eventually cooling, and then
        much of it returns to the equator
           This creates the ‘Trade Winds’,
           between 0° and 30° Lat. and an
           area of calm (rising) wind
           at the equator, called the

                         Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   4
                         Air Circulation
       Other predictable Wind patterns include:
          Prevailing Westerlies, are cooling air moving towards the
           poles between 30° and 60° latitude
          Above 60° latitude cooling and descending polar air forms
           Polar Easterlies
   VERY large Temperature and Pressure differences, high up
    (in the Troposphere) cause special high speed winds called
    Jet Streams
      These travel in a band around the earth at between 100
        and 300 MPH
      There are 4 jet streams, one of
        which is over the United States
          Ours is at 30,000 to 35,000 ft, and
           travels West to East, dipping South
           over the Mid West (but it moves!)
                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   5
                       Air Circulation
   Important Terms (Quiz):
     Autumnal    Equinox                                     Coriolis Effect
        Equal length Day/Night                               Jet Stream
        (Fall - Sept 22/23)
                                                              Radiation
     Vernal   Equinox
                                                              Revolution (of Earth
        Equal length Day/Night
        (Spring - March 21/22)                                 around Sun)
                                                                       How long does it
     Summer    Solstice                                                  take?
        Longest Day (June 21/22)
                                                              Rotation              (of Earth)
     Winter   Solstice                                                What angle is the
        Shortest Day (Dec 21/22)                                         earth’s axis tilted at?

                      Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing                6
                       Weather Elements

   Wind
       ‘A body of air in motion’
       Wind is defined by its Direction and Speed
           e.g. Easterly (FROM the East) at 20 knots
           1 knot = 1.1 MPH
       The Beaufort Scale (0 to 12) defined different wind strengths,
        by describing visible effects for different Wind Speeds
       Wind can make the air feel colder than it is - this effect is
        called Wind Chill
           The wind is removing the warm air from around your body, and
           speeding heat loss
          A chart can be used to determine the wind chill
          Flying into wind increases lift, flying with the wind increases
           speed, flying cross-wind pushes you off course.

                         Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   7
                      Weather Elements
       Microburst
          A very strong, very fast moving downdraft, often from a
           thunderstorm, resulting in extreme turbulence
   Temperature
     Temperature is the result of Heating, and is measured in degrees
      Fahrenheit (°F) or Celsius/Centigrade (°C)
     Conversion: F = (1.8xC)+32 C=(F/1.8)-32
        no need to memorize these equations
       Water Boils at 212°F and Freezes at 32°F (100 & 0 °C)
     Heat is defined as ‘the total Energy of all Molecules (illustrated by
      their motion) within a substance’
     Temperature is therefore defined as ‘a measure of molecular motion,
      using a man-made scale’
     Heat, and therefore Temperature affects air Pressure and Density,
      and is therefore VERY important information for Pilots
         e.g. high temperature = lower density = LESS LIFT
                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   8
                     Weather Elements
   Pressure
       A gas pressing on another, or a surface results in Pressure
       Atmospheric Pressure is the effect of air pushing down on
        the Earth’s surface
       As molecules collide, movement results
       Measurement of Atmospheric Pressure:
           Mercury Barometer - Accurate, Reliable and Stable, used by
          Aneroid Barometer - Fast and Easy to Read, but not particularly
          Aneroid Barograph - Provides a permanent record of pressure
           changes, using a pen and a revolving drum of paper
       Atmospheric Pressure affects air density, and differences
        causes bodies of air to move, thus creating wind.

                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   9
                    Moisture and Clouds
   Moisture
       Moisture is Water in Solid (Ice), Liquid (Water), or Gaseous
        (Vapor) form
       The air can only hold a limited amount of water vapor, when is
        contains the maximum amount, it is Saturated
       Saturation depends on temperature, the temperature at which
        the air WILL become saturated is called the Dew Point
       Add more moisture, or decrease the temperature BELOW the
        Dew Point, and Condensation (conversion to liquid) occurs
           Clouds and Fog are both forms of Condensation
       Humidity describes the amount of moisture in the air
           The normal measure is Relative Humidity, which is the % of
           saturation which has been reached, e.g. 70%
 Fog - mass of water droplets in suspension (Ground Level Cloud)
       Occurs when Temp & Dew Point are within 5° and wind is low

                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   10
                     Moisture and Clouds
   Clouds
       Like Fog, Clouds are a mass of water droplets in suspension,
        but they can also contain ice crystals, or water / ice mixed
       There are 3 basic Cloud Forms:
          Cumulus - White, Billowy, Puffy (Cotton Balls), Low Level
             – Normally seen in good weather, but also associated with turbulence
          Stratus - Thin, Sheet like, Grey, Low Level
          Cirrus - White, Thin, Wispy, High Level
   Precipitation
       When the temperature fall too far below the Dew Point, and the
        Cloud can no-longer hold the moisture in suspension,
        Precipitation Results
          Either Rain, Snow or Ice (hail) depending on temperature
          Precipitation is measured with a Rain Gauge
          Precipitation reduces Visibility, and makes runways slippery
          Ice increases Aircraft weight, and can block inlets
                          Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   11
          Weather Systems and Changes
   Air Masses - A HUGE mass of air
       Normally at least 1000 miles across
       Essentially the same Temperature and Moisture
        characteristics throughout
       Air masses are classified by where they came from, i.e. their
        Source Region
       The 6 Source Regions are:
          cA - continental Arctic
          cP - continental Polar
          cT - continental Tropical
          mT - maritime Tropical
          mP - maritime Polar
          mE - maritime Equatorial
       Maritime masses are wetter
       Farther away from the equator = a colder mass
                       Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   12
          Weather Systems and Changes
   Fronts - the boundary between 2 air masses:
     WARM Fronts ride up over Cold Air
     Normally COLD Fronts are heavy and low,
      and push Warm Fronts up, and away
     When similar air masses meet, there may not be
      enough difference to cause movement, and a
      STATIONARY Front occurs
     An OCCLUDED Front (3 air masses) the Warm
      air is still pushed up, but relatively cool air is
      pushed up also by colder air
         Cold Occluded - Old Cool Air pushed up,
           basically like a Cold Air snowplough, pushing
           everything Upwards
         Warm Occluded - New
           Cool Air pushed up
           behind Warm Air, by
           local colder air

                        Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   13
           Weather Systems and Changes
   Severe Weather
       Cumulonimbus clouds are a sign of Severe Weather, which
        could be a Thunderstorm, Tornado or Hurricane
       Thunderstorms
          Heavy Winds, Strong Rain, Sometimes Hail
          Lightning - Electric Discharge, which can heat the air to 60,000°F!
             – About 200 are killed and 600 injured by lightning in the US annually!
             – 3 stages: Building (Updrafts), Mature (Up/Down air cycles),
               Dissipating (Downdrafts)
          Do’s and Don’ts:
             –   Don’t use electric appliances, telephones, or take a shower
             –   DO Stay away from Windows and Doors
             –   If Outdoors, DO go Inside
             –   If in a car, DO stay there
             –   If in a boat, DO get ashore
             –   DO Move away from Water and Metal objects
             –   Don’t stand in open space, or under a tree
             –   DO Stay Low, and Don’t huddle in a group
                            Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   14
       Weather Systems and Changes
   Tornadoes
      Fujita Wind Damage Scale - F0 to F5, with wind speed range and
       expected scale of damage for each
          – F5 is over 261 MPH, with ‘Incredible’ Damage resulting
          – Do’s and Don’ts:
               » DO Get to a Basement (or lie down in low ground)
               » DO, If above ground, move at 90° to the Tornado
               » DO, if indoors, stay away from windows, got to the interior, or
                 into a closet or bathroom
   Hurricanes
      Saffir-Simpson Hurricane Damage Potential Scale -
       Cat 1 (75-95 MPH), to Cat 5 (155+ MPH!), with Pressure Range,
              Wind Speeds, and Storm Surge (Sea Level increase)
          –   Do’s and Don’ts:
          –   same as Thunderstorms & Tornadoes, since they can produce BOTH
          –   Worse, they can be HUGE, and can continue for more than a week!
          –   But, Hurricanes have a ‘Eye’ at the center which is calm

                       Dr. R.A. Bartholomew   -   Civil Air Patrol, New Jersey Wing   15

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