CPL Meteorology PDF

🔆 CPL Meteorology Created @November 19, 2024 7:21 AM Class MET Course CPL Meteorology “Weather is an important factor that influences aircraft performance and flying...

🔆 CPL Meteorology Created @November 19, 2024 7:21 AM Class MET Course CPL Meteorology “Weather is an important factor that influences aircraft performance and flying safety.” (FAA, 2016) Branch of science that deals with the physical properties of the atmosphere expected to have fundamental knowledge of weather theory should know how to access and interpret the services available horizontal Overview The atmosphere pressure density temp humidity precipitation wind Cloud information, fog, mist, and haze CPL Meteorology 1  Air masses, frontology, ice accretion, thunderstorms flight over mountainous areas, climatology, altimetry Aviation Weather Service Atmosphere blanket of air made up of a mixture of gases that surrounds the earth Nitrogen 78% of gas, Oxygen 21%, other gases 1%, water vapor 0%-5% helps us breathe regulates temp protects from space vacuum Troposphere: up to 20000ft decrease in temperature with altitude contains most of the atmosphere’s mass most weather here because uneven heating of the earth’s surface tropopause: traps moisture Stratosphere much of the same composition as the troposphere certain types of clouds occasionally extend to it severe thunderstorms occur here (199 to 22 miles) less turbulent air so most commercial flight occurs here tropopause to 160000ft Mesosphere 45 to 51 miles (M) meteors burn up in this part of the atmosphere no weather phenomenon Thermosphere CPL Meteorology 2  outermost layer of the atmosphere Atmospheric Circulation Uneven heating of earth root cause of all atmospheric events modifies air density, creates circulation patterns hotter near equator changes in air pressure pressure differs due to altitude, temp, and air density Convection/Process of Convection CPL Meteorology 3  circulating motion that results when warm air rises and is replaced by cool air static circulation Convection: vertical movement of the air Advection: horizontal movement of air Coriolis Force force created by the rotation of the Earth that deflect static circulation pattern in the northern hemisphere the wind is always deflected to the right in the southern hemisphere the wind is always deflected to the left Polar cell Rises at 60, down at 90 Ferrel cell rises at 60, down at 30 moist Hadley cell rises at equator sinks at 30 degrees CPL Meteorology 4  Polar easterlies: polar easterlies are the dry, cold prevailing winds that blow around the high-pressure areas of the polar highs from the east Westerlies: prevailing winds that blow from the west at midlatitudes. strong winds in the southern hemisphere Horse latitudes: narrow zone of warm dry climates between trade winds and westerlies winds go down Trade winds: CPL Meteorology 5  permanent east-to-west prevailing winds that flow in the Earth's equatorial region predictable path Doldrums where trade winds meet winds go up Intertropical Convergence Zone weak winds, calm weather affects air mass or bodies of water air to the right in the northern hemisphere Pressure Systems LPA NH: counterclockwise SH: clockwise HPA NH: clockwise SH: counterclockwise CPL Meteorology 6  Atmospheric Pressure and Temperature Measure of Atmosphere Pressure measured by barometer aneroid barometer easier to read and transport aneroid cell contracts and expands with pressure ISA: 29.92 in Hg or 1013.2mb/hPa Standard Temp: 59F 15C Density alt as pressure decreases DA increases ISA = 15 - (PA/1000)2˚C ISA DEV TEMP = OAT - ISA OAT = ISA TEMP + ISA DEV TEMP CPL Meteorology 7  QNH = ISA P + ISA Dev ISA P = 29.92 - lapse rate ISA DEV P = QNH - ISA P Standard Lapse Rate temp drops 2 degrees per 1000ft increase pressure drops by 1 inch Hg every 1000ft increase Pressure Values QFE - pressure at the datum level of the airfield /aerodrome QNH - the QFE reduced to MSL during ISA conditions Air Density amount of mass of air per unit volume varies directly proportional to air pressure varies inversely proportional to air temperature varies inversely proportional to humidity of air Effects of Atmospheric Pressure on Flight decreased pressure results in: decreased aircraft performance Effects of Atmospheric Pressure on the Human Body decreased atmospheric pressure results in decreased partial pressure of oxygen hypoxia mild disorientation to total incapacitation Altitude less dense air, more speed required to takeoff sea level = normal growth and life 18000ft = adverse effects on body 10000ft = reactions impaired CPL Meteorology 8  Wind and Currents What are winds? air flowing from regions of high pressure to regions of low pressure, or Coriolis force winds are party responsible for weather phenomenon Turbulence sudden, violent shift in airflow caused by irregular atmospheric motion high to low pressure is to the right in northern hemisphere Light vertical displacement of up to 1 meter Moderate vertical displacement of 3-6 meters Severe vertical displacement of up to 30 meters High pressure air systems dry stable descending Low pressure air unstable moist Mountain Waves turbulent eddies found downwind a mountain range causes lenticular clouds CPL Meteorology 9  Jet Streams fast moving streams of air at higher altitudes blowing eastward caused by “breaks” in the tropopause weaker in the north during the summer stronger in the south during the winter polar jet streams between polar and ferrel cells subtropical jet streams 30˚ latitudes 33000 ft to 52000 ferrel and hadley cells Local Wind Patterns 1. Sea Breeze wind that blows from cool water to warm land 2. Land Breezes wind that blows from cool land to warm water CPL Meteorology 10  3. Valley Wind cooler air over the valley sinks and air close to the mountain flows upward foehn: warm descending wind Anabatic Winds Uphill Flow: These winds flow uphill from valleys to mountain slopes. Daytime Phenomenon: They are most prominent during the day when mountain slopes warm more rapidly than valley floors. Warm, Less Dense Air: Warm, less dense air rises from the valley floor up the mountain slopes. Cloud Formation: As the warm, moist air rises, it can cool and condense, forming clouds. 4. Mountain Wind cooler air flows down the slope and displaces the air in the valley Katabatic Winds Downhill Flow: These winds flow downhill from higher elevations to lower elevations. CPL Meteorology 11  Nighttime Phenomenon: They are most prominent at night when mountain slopes cool more rapidly than valley floors. Cold, Dense Air: Cold, dense air accumulates on the mountain slopes and flows downhill under the influence of gravity. Examples: Santa Ana winds in California and Bora winds in the Adriatic Sea So, during the day, the valley experiences high pressure, and the mountain slopes experience low pressure. At night, the opposite occurs: the valley experiences low CPL Meteorology 12  pressure, and the mountain slopes experience high pressure. 💡 Foehn winds are warm, dry winds that descend the leeward slopes of mountain ranges. They're often referred to as "snow-eaters" because of their ability to rapidly melt snow and ice. Low Level Wind Shear sudden, drastic change in wind speed and/or direction over a very small area Microburst most severe type of low-level wind shear sinking air in thunderstorm presents significant threat to all aircraft violent up and down drafts and horizontal movement low-level is hazardous 1-2 nautical miles in diameter less than 1000ft vertical distance downdrafts of 6000ft per minute 20 nautical miles away from a thunderstorm CPL Meteorology 13  Convective currents uneven surface heating causes turbulence can be avoided by flying at higher altitudes also observable where land meets water over land air rises, over water air sinks The Lifting Condensation Level (LCL) is the altitude at which a parcel of air, lifted adiabatically, becomes saturated with water vapor and forms clouds CPL Meteorology 14  Wind Obstruction mechanical obstruction result in chaotic airflow mechanical turbulence friction of air and ground, causing turbulence in lower trees CPL Meteorology 15  Wind Symbols arrow attached to circle arrow points to direction wind is flowing from each barb is 10kts pennant = 50 kts estimate only Pressure and Winds a. Isobars line on a weather chart that shows equal or constant barometric pressure b. Pressure Gradient representation of change in pressure over a given distance closer together: strong and fast winds c. Pressure systems High - anti-cyclonic, clockwise Low - cyclonic, counter CPL Meteorology 16  Ridge - an elongated area of high Trough - an elongated area of low Col - intersection between ridge and trough, or an area of neutrality between two highs or two lows Atmospheric stability stability of air dictates its resistance to vertical movement combined effects of temp and moisture determines stability of air and types of weather product stable air: cool and dry, resists vertical movement unstable air: warm and moist Stable Air Characteristics Unstable Air Stratus Type Clouds Cumulus Steady Precipitation Showery Stable/Smooth Air Turbulent Steady Winds Gusty Poor Visibility Good CPL Meteorology 17  Absolute Instability air continues to rise environmental lapse rate exceeds dry adiabatic lapse rate 💡 theoretical standard lapse rate: -1.8C/1000ft dry adiabatic lapse rate is faster than wet Inversion a layer of air where temperature increases as altitude increases shallow layers of smooth, stable air Marine Inversion Along coastlines, cool, dense air from the ocean can flow inland and form a temperature inversion over warmer land. CPL Meteorology 18  near large bodies of water Nighttime or Radiation inversion temp reverses when the air near the ground is cooled of faster than the layer of air above it At night, the Earth's surface cools rapidly, cooling the air in contact with it. CPL Meteorology 19  If this cooling is more rapid than the cooling of the air above, a temperature inversion can develop near the surface. Frontal inversion warm air mass overrides a cold air mass At the boundary between warm and cold air masses, a temperature inversion can form. Subsidence Inversion CPL Meteorology 20  wide/large descending air mass compresses and warms due to increase in pressure Large-scale sinking air, often associated with high-pressure systems, can compress and warm as it descends. This warm air can form a layer above cooler air near the surface, creating an inversion. Effects of inversion low visibility: fog thunderstorms Atmospheric Moisture Humidity CPL Meteorology 21  moisture content in the air Relative Humidity actual amount of moisture in the air compared to the total amount that could be present at that temperature Dew Point temperature at which air reaches a state where it can hold no more water relative humidity is 100% Methods of adding moisture to air 1. Evaporation 2. Condensation 3. Sublimation: solid to gas 4. Deposition/de-sublimation 5. Melting 6. Freezing Methods of reaching saturation point Air cools and reaches its saturation point when: 1. Warm air moves over a cold surface 2. cold air and warm air mix 3. air cools at night through contact with the cool ground 4. air is lifted or forced upward in the atmosphere clouds, fog, dew form Dew forms when water vapor condenses and deposits itself on a surface as a result of being air cooled by the ground Frost frost forms like dew, but with the temperature at or below freezing CPL Meteorology 22  Fog cloud near the surface visible moisture within 50 ft of the ground Types of Fog: Radiation fog: Forms on clear nights when the ground cools rapidly, cooling the air above it to its dew point. terrestrial heating, calm wind mountain areas Advection fog: requires winds up to 15kts forms low stratus clouds warm moist air moving over a cold surface cools to its dew point coastal areas Upslope fog: requires wind, not dissipated by heat up a slope Evaporation fog: cold dry air moves over warm water Precipitation fog: warm rain over cool air near the surface Ice fog: below freezing, vapor turns into ice crystals adiabatic cooling: rising air expands and cools due to the decrease in air pressure as altitude increases CPL Meteorology 23  adiabatic heating: as atmospheric pressure increases, temp of descending air increases as it is compressed Haze and Smog smog is smoke and fog haze is reflection of sun off particles suspended in the air Clouds composed of very small droplets of water visible moisture that has condensed or sublimated onto condensation nuclei Cloud types Low: surface to 6500 AGL Medium: 6500 to 20000AGL High: 20000 to UNL CPL Meteorology 24  Condensation nuclei tiny particles in the atmosphere that water vapor condenses onto to form water droplets or ice particles Species of Clouds Low more prone to icing because of humidity 1. Stratus - layered clouds that form in stable air near the surface due to cooling from below 2. Stratocumulus - white and puffy clouds 3. Nimbostratus - grey or black, more than several thousand ft thick, precipitation Middle made of water and supercooled water droplets + ice crystals severe icing conditions compared to low clouds 1. Altostratus - widespread dark clouds, flat dense clouds covering a wide area with gray or white 2. altocumulus - puffy clouds at middle elevation, gray, white patchy clouds High mainly ice crystals no threat to icing and turbulence 1. Cirrus - thin, wispy, narrow band 2. Cirrostratus - thin, white, in long sheets against a blue bg 3. Cirrocumulus - white, patchy like cotton Vertical Development 1. cumulus 2. cumulonimbus CPL Meteorology 25  Others 1. Castellanus - common base w/ separate vertical development, rising towers, turrets 2. Lenticular - lens shaped forms over mountains 3. Fracto/Fractus - ragged or broken fragments 4. Kelvin-Helmholtz clouds/fluctus - waves 5. Mamatus clouds - look like ball sacks Cloud Properties Sky/Cloud cover fraction of the sky obscured by clouds divide the sky by 8 CPL Meteorology 26  Ceiling vertical distance between ground level and the base of the lowest layer of broken or overcast clouds CPL Meteorology 27  Visibility greatest horizontal distance at which prominent objects can be seen ☁️ T - DP x 400 = Cloud Ceiling T - DP = spread Precipitation any type of water that form in the atmosphere and fall to the ground drizzle: rain smaller than ø = 0.02” sleet, freezing rain, rain, hail, graupel, snow freezing rain notes dump 1. Rain Rain is a form of precipitation that is in the form of water drops of a size larger than 0.5mm. The maximum raindrop size is about 6mm. Drops of larger size CPL Meteorology 28  break up into smaller drops as it falls down. Rainfall is the predominant form of precipitation and hence the term precipitation is used synonymously with rainfall. The magnitude of rainfall shows high temporal and spatial variation. This variation is responsible for the occurrence of hydrologic extremes such as floods and droughts. 2. Snow Snow consists of ice crystals in a flaky form (average density ~ 0.1g/cc). It is also an important form of precipitation. 3. Drizzle Drizzle is a fine sprinkle of tiny water droplets of size less than 0.5mm and intensity greater than 1mm/h. The tiny drops forming a drizzle appear to float in the air. 4. Glaze (Freezing Rain) The glaze is formed when rain or drizzle comes in contact with the cold ground at around 0 degrees celsius. The water drops freeze to form an ice coating. 5. Sleet Sleet is frozen raindrops formed when rainfall passes through the air at subfreezing temperatures. 6. Hail Hail is a type of showery precipitation in the form of pellets or lumps of size greater than 8mm. Hail occurs in violent thunderstorms. 7. Graupel frosty kind of snow, snow crystals in the cloud collide with very cold water droplets droplets freeze loosely onto the snow, slushy texture Air Mass large body of air with fairly uniform temperature and moisture content CPL Meteorology 29  classified by Source Regions area where an airmass acquires the properties of temperature and moisture that determine its stability 1. Temperature 2. Moisture i.e. Maritime Polar/tropical, continental polar/tropical, continental arctic Fronts when an airmass moved out of its source region, it comes in contact with other airmasses that have different moisture and temperature characteristics boundaries between air masses frontogenesis: creation of a front frontolysis: death of a front Warm Front warm air catches up to a cold air mass CPL Meteorology 30  warm air stays on top creating clouds results in poor visibility barometric pressure falls until the front passees 10-25mph Cold Fronts when a mass of cold, dense, and stable air advances and replaces a body of warmer air. 25-30mph so dense, it stays close to the ground and acts like a snowplow, sliding under the warmer air and forcing the less dense air aloft cumulonimbus, rain, barometric pressure rises Stationary Front forces of two air masses are relatively equal typically a mixture that can be found in both warm and cold fronts thunderstorms longest weather conditions Occluded fronts get their name from the fact that the warm air mass becomes "occluded" or cut off from the ground as the colder air mass advances. fast-moving cold front catches up with a slow-moving cool front cold front occlusion occurs when a fast moving cold front is colder than the air ahead of the slow moving warm front mixture of weather found in both warm and cold fronts, providing the air is relatively stable warm front occlusion occurs when the air ahead of the warm front is colder than the air of the cold front. weather is more severe than the weather found in a cold front occlusion CPL Meteorology 31  Thunderstorm characterized by CB clouds, lighting, and thunder need moist unstable airmass that has lifting action contains strong winds, icing, hail, lightning etc condensation of nuclei counterclockwise rotation NH stay 20sm away CPL Meteorology 32  45-60 1. Cumulus stage convective updrafts building cumulus clouds 2. Mature stage onset of rain, continuation of updrafts, and downdrafts from the rain 20-40 mins most violent: up/downdrafts, precipitation, lightning etc. anvil on top 3. Dissipating stage the downdrafts spread out and replace the updrafts needed to sustain the storm Thunderstorm Hazards Squall Line narrow band of active thunderstorms CPL Meteorology 33  on or ahead of cold fronts Tornadoes vortex formed by air drawn into a thunderstorm cloud with initial rotating motion water spout over water Turbulence chaotic changes in pressure and flow velocity Light: 5-15kts Moderate: 15-25kts Severe: 25kts above Icing can form when: there is water in liquid state OAT is below 0˚C airframe temp is 0˚C and below can lead to: 30% reduction in lift 40% increase in drag increase in weight CPL Meteorology 34  light: occasional use of de-ice required change of heading or alt not required moderate de-ice necessary change of heading or alt is desirable severe de-ice insufficient change of heading or alt is necessary clear ice: supercooled droplets do not freeze on impact, freeze to the shape of the airfoil below or at freezing temperatures temp of the skin is at 0˚C to -10˚C mixed -10˚C to -15˚C rime: supercooled droplets freeze on impact -15˚C to -20C Hail Supercooled drops above the freezing level begin to freeze water continues to accumulate on an already frozen droplet Ceiling and Visibility visibility nears zero within a thunderstorm cloud CPL Meteorology 35  ceiling generally is close to the ground Effect on Altimeter pressure drops rapidly with the approach of a thunderstorm, rises sharply with the onset of the first gust and arrival of heavy rain showers, and falls back to normal as the storm moves on ⛈️ high to low, look out below, low to high, clear the sky Lighting electrical discharge friction between ice crystals and water droplets positive charge lighter ice crystals up Climatology study of climate and its variations over time Philippine Seasonal Weather and Winds 2 Seasons: Wet season: June - October Southwest Monsoon (habagat) Dry season November - February (cool dry) March - May (hot dry season) Northeast Monsoon (amihan) CPL Meteorology 36  Aviation Weather Services weather observations service outlets weather briefings aviation weather reports aviation forecasts weather charts ATC radar weather displays data link products Surface Aviation Weather Observations observed weather at individual ground stations (METARs) CPL Meteorology 37  data sources can be automated: AWOS (Automated Weather Observing System), ASOS (Automated Surface Observing System) provide continuous up-to-date weather information. Air Route Traffic Control Center (ARTCC) provides separation for IFR traffic and can view precipitation echoes on their radar displays Upper Air Observation weather gathered from the upper atmosphere through\: Pilot observations (PIREPs) Automated data collection weather balloon using radiosonde AMD Radar Observations distance strength, size and number, wind direction, and speed radio waves bouncing off of moisture in the air color coded display according to precipitation intensity 1. NEXRAD (Next Generation Weather Radar) 2. FAA terminal Doppler weather radar (TDWR) 3. FAA airport surveillance radar 4. Aircraft onboard radar (WSR) Satellite satellite LIDAR (light detection and ranging) a laser altimeter system that determines the distance by measuring pulse travel time range and altitude, temp, cloud cover, wind velocity, sea surface roughness Service Outlets CPL Meteorology 38  Flight Service Station (FSS) primary source for preflight weather information Telephone Information Briefing Service (TIBS) recordings of meteorological and aeronautical information accessible through a touchtone only Hazardous Inflight Weather Advisory Service (HIWAS) Automated continuous broadcast of weather information through a VOR us only Transcribed Weather Broadcast (TWEB) automated continuous broadcast of meteorological and aeronautical data over Low, Medium, and VHF NAV AIDS Weather Briefings provided by a specialist at an FSS data given is dependent on your flight details and requested briefing type 1. standard briefing 2. abbreviated briefing 3. outlook briefing Standard Briefings provides the ff info: 1. Adverse conditions weather, aerodrome, airport, runway 2. VFR flight not recommended 3. synopsis type, location and movement of weather systems and/or air masses which might affect the proposed flight CPL Meteorology 39  4. current conditions METAR/PIREPs 5. en route forecast weather otw to destination considering estimated time at waypoints 6. destination forecast weather at destination and at ETA 7. forecast winds and temperatures aloft wind at cruising altitudes 8. NOTAMs 9. ATC Delays any delays for your proposed flight 10. Other information Abbreviated Briefing shortened version of a standard briefing and is requested if departure is delayed Outlook Briefing a briefing to be requested if departure is more than 6 hours away Weather Reports METAR METARs are published every hour and valid every hour CPL Meteorology 40  SPECI METAR unscheduled report TAF (Terminal Aerodrome Forecast) a forecast of weather conditions within 5 SM every 6 hours valid for 24 hours published 4 times a day Area Forecasts (FA) gives a picture of clouds, general weather conditions, and visual meteorological conditions expected over a large area issued 3 TIMES A DAY, valid for 18 hours 12 HOURS FORECAST 6 HOURS OUTLOOK 4 Sections: 1. Header - source, date and time, validity, coverage CPL Meteorology 41  2. precautionary statements - IFR conditions, mountain obscurations, thunderstorm hazards 3. synopsis - movement of pressure systems and fronts 4. VRF Clouds and weather - sky conditions, visibility PIREPS pilot reported weather observations pilot may file it with an FSS or ATC AIRMET (WAs) every 6 hours AIRman's METeorological Information operational interest to all aircraft but weather phenomenon potentially hazardous to light aircraft SIGMET (WSs) CPL Meteorology 42  valid for 4 hours or 6 hours if related to a hurricane advisories concerning non-convective weather potentially hazardous to all aircraft Convective Significant Meteorological Information (WST) advisories issued for hazardous convective weather hazardous to all flights Wind and Temperature Aloft Forecast (FB) provides wind and temperature forecasts throughout specific locations Surface Analysis Chart depicts an analysis of the current surface weather, transmitted every 3 hours depicts pressure regions, fronts, temperatures, dew points, wind direction and speed, local weather and visual observation Weather Depiction Chart depicts surface conditions as derived from METAR and other surface observations depicts cloud conditions and ceilings, fronts, local weather and visual obscuration 3 hours Significant Weather Prognostic Chart depicts surface conditions as derived from METAR and other surface observations depicts cloud conditions and ceilings, fronts, local weather and visual obscuration 4 times a day CPL Meteorology 43