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

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’

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

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  1. Cadet Phase I & IIAerospace DimensionsAir 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

  2. 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

  3. 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

  4. 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 ‘Doldrums’ Dr. R.A. Bartholomew - Civil Air Patrol, New Jersey Wing

  5. 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

  6. Air Circulation • Important Terms (Quiz): • Autumnal Equinox • Equal length Day/Night (Fall - Sept 22/23) • Vernal Equinox • Equal length Day/Night (Spring - March 21/22) • Summer Solstice • Longest Day (June 21/22) • Winter Solstice • Shortest Day (Dec 21/22) • Coriolis Effect • Jet Stream • Radiation • Revolution (of Earth around Sun) • How long does it take? • Rotation (of Earth) • What angle is the earth’s axis tilted at? Dr. R.A. Bartholomew - Civil Air Patrol, New Jersey Wing

  7. 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

  8. 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

  9. 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 Scientists • Aneroid Barometer - Fast and Easy to Read, but not particularly accurate • 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

  10. 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

  11. 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

  12. 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

  13. 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 • ColdOccluded - Old Cool Air pushed up, basically like a Cold Air snowplough, pushing everything Upwards • WarmOccluded- New Cool Air pushed up behind Warm Air, by local colder air Dr. R.A. Bartholomew - Civil Air Patrol, New Jersey Wing

  14. 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

  15. 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

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