Weather Theory: pressure, density altitude, wind, moisture, clouds and fronts
The short version
- Everything in weather reduces to two variables - PRESSURE and TEMPERATURE. Both change how your aircraft performs and both drive how weather forms.
- DENSITY ALTITUDE is the number that matters. It is the altitude your aircraft "feels like" it is flying at. High density altitude means worse performance.
- The two standard-day numbers to memorise - 15 degrees C and 29.92 inHg at sea level. Temperature falls 2 degrees C per 1,000 ft; pressure falls 1 inHg per 1,000 ft.
- Temperature and dew point CONVERGING means visible moisture - fog, cloud, dew or frost. It is the single most useful weather read for a drone pilot.
- Stable air gives layered stratiform cloud, steady precipitation and POOR visibility. Unstable air gives puffy cumuliform cloud, showers, turbulence and GOOD visibility.
The concepts
Atmospheric composition and the troposphere 0:04:15
The atmosphere is roughly 78% nitrogen, 21% oxygen and 1% other gases. Weather occurs in the TROPOSPHERE, the lowest layer.
Temperature decreases about 2 degrees CELSIUS per 1,000 ft of climb. Memorise this.
Airliners cruise around 35,000-40,000 ft partly to fly ABOVE most weather.
Uneven solar heating of the earth drives all air movement - warm air rises, cold air sinks - producing both global and local circulation.
An AIR MASS is a volume of air with uniform temperature and characteristics.
Atmospheric pressure and its units 0:08:15
Pressure is the weight of air molecules on a unit area. Standard sea level pressure is 14.7 psi, 29.92 inches of mercury, or 1013.2 millibars / hectopascals.
Pressure decreases about 1 INCH OF MERCURY per 1,000 ft.
At 18,000 ft the pressure is about HALF the sea level value.
Inches of mercury comes from the mercury barometer - more pressure pushes the column higher.
Metric reporting uses hectopascals/millibars; 1013.2 hPa equals 29.92 inHg.
The standard day 0:11:26
A reference condition of 15 degrees C (59 F) and 29.92 inHg AT SEA LEVEL, against which all aircraft performance is calculated.
Warmer than standard, or lower pressure than standard, both DEGRADE performance.
The standard values change with elevation - at 5,000 ft the standard is 5 degrees C and 24.92 inHg.
Manufacturer performance data assumes standard conditions.
The actual altitude at which you are is not always the way that the drone is going to be performing.0:11:26
Pressure altitude 0:19:46
Altitude corrected for NON-STANDARD PRESSURE - the height above the 29.92 inHg reference plane.
Formula (not required for the exam) - (29.92 - current altimeter setting) x 1,000 + field elevation.
Worked example - field at 5,000 ft with altimeter 29.79 gives 5,130 ft pressure altitude.
Low pressure raises pressure altitude (worse performance); high pressure lowers it.
IMPORTANT - reported altimeter settings are CORRECTED TO SEA LEVEL. A 5,000 ft field reporting 29.92 actually has about 24.92 inHg of real pressure outside. The reporting convention exists for manned aircraft altimeters.
Density altitude - the number that actually matters 0:25:49
Pressure altitude corrected for NON-STANDARD TEMPERATURE. It is the altitude at which the aircraft performs as though it were flying.
Formula (not required) - (local temp C - standard temp C at that altitude) x 120 + pressure altitude.
Worked example - pressure altitude 3,000 ft, OAT 12 C. Standard at 3,000 ft is 15 - 6 = 9 C. (12 - 9) x 120 + 3,000 = 3,360 ft density altitude.
Sea level illustration - standard day gives 0 ft; 35 C gives about 2,400 ft; -5 C with 30.92 inHg gives about MINUS 3,400 ft; 35 C with 28.92 gives about 3,400 ft.
At a 5,000 ft field - hot and low pressure can feel like 8,400 ft; cold and high pressure like 1,600 ft.
The naming trap - HIGH pressure means HIGH air density but LOW density altitude, which is GOOD. Read 'density altitude' as one hyphenated word.
High pressure means high air density, but it means low density altitude.0:29:06
What high density altitude actually degrades 0:33:13
Every performance parameter suffers as density altitude rises.
Longer TAKEOFF and LANDING distances (fixed wing) - a familiar short strip may become too short.
Reduced RATE OF CLIMB - obstacle clearance may no longer work.
Lower service CEILING - the aircraft may not reach the altitude you need.
Reduced PAYLOAD capacity.
Reduced RANGE and endurance, and worse fuel or battery economy.
Lower achievable SPEED, and degraded manoeuvrability and stability - the "mushy" feel the instructor describes at 12,000 ft.
Lower humidity is better than higher humidity, though the effect is smaller and rarely charted.
Wind, pressure gradient and isobars 0:36:40
Wind is HORIZONTAL air movement, caused by air flowing from high pressure toward low pressure. Isobars are lines of equal pressure.
CLOSELY spaced isobars mean a steep pressure gradient and STRONG wind; widely spaced isobars mean light wind. The instructor's ski-slope analogy.
In the northern hemisphere - HIGH pressure circulates CLOCKWISE and OUTWARD; LOW pressure circulates COUNTERCLOCKWISE and INWARD.
High pressure pushes weather away and generally brings good conditions; low pressure draws air in and lifts it, generally bringing poor conditions.
Isobars are labelled in millibars.
Convective currents and terrain effects 0:41:23
Convective currents are VERTICAL air movements driven by uneven surface heating.
Rock, sand, barren ground and paved parking lots reflect heat and create UPDRAFTS.
Water, trees and vegetation absorb heat and produce DOWNDRAFTS.
Crossing from a parking lot to a lake produces a lift then a sink - the instructor could count down his students' approach every hot afternoon.
Buildings deflect wind; expect sudden gusts at street corners and between towers.
On the LEE side of a mountain, wind curls DOWNWARD - it can push a drone into the slope faster than it can climb out.
Sea breeze and land breeze 0:46:04
Coastal daily wind reversal driven by the different heating rates of land and water.
SEA BREEZE (day) - land heats faster, air rises over land, cooler air flows in FROM the water.
LAND BREEZE (night) - land cools faster, water stays warmer, flow reverses and moves OUT toward the water.
Operational risk - a land breeze pushes you offshore easily and then you must fight it home on a depleted battery.
Low-level wind shear and microbursts 0:48:20
A sudden, drastic change in wind speed and/or direction over a very short distance. A microburst is a concentrated, violent downdraft.
Microbursts last roughly 5-15 minutes, produce downdrafts up to 6,000 ft per minute, and wind changes of 30 to 90 knots.
Associated with THUNDERSTORMS - the main reason not to fly near one.
The three-stage encounter - headwind (performance increases), then downdraft (forced down), then tailwind (performance collapses and you cannot return).
It can occur in dry air with no visible rain shaft.
Temperature, dew point and saturation 0:51:07
The DEW POINT is the temperature to which air must be cooled to become SATURATED - holding all the water vapour it can. Fog and cloud are visible moisture formed when air reaches its dew point.
The CLOSER the temperature and dew point, the more likely fog, cloud, dew, frost or precipitation.
Fog IS cloud - the only difference is height above the surface.
Both values appear in ATIS, AWOS, ASOS and METAR reports.
The water-bottle analogy - once full, any more water spills out as condensation.
When the dew point and the temperature are really close to each other, it's a good sign that the visibility outside is going to suck.0:51:07
Frost 0:54:37
Forms when the dew point is BELOW FREEZING and the collecting surface is also below freezing.
Ice on propellers creates severe vibration, can destroy motors and bring the aircraft down.
Another reason not to fly in visible moisture - beyond the 3 statute mile visibility rule.
Four ways air reaches saturation 0:56:10
All four involve COOLING an air mass to its dew point.
Warm air moving over a COLD SURFACE.
A warm air mass COLLIDING with a cold air mass.
Ambient temperature falling at NIGHT with the air mass in place.
An air mass being LIFTED, cooling at about 2 degrees C per 1,000 ft.
The four types of fog 0:58:12
Fog classified by the mechanism that cooled the air to its dew point.
RADIATION fog - ground cools rapidly overnight, chilling still air above. Needs LITTLE or NO wind, forms in valleys, burns off with morning sun.
ADVECTION fog - warm moist air moves over a colder surface. Needs WIND (up to about 15 knots). Common in coastal areas.
UPSLOPE fog - air pushed up rising terrain cools as it climbs. Needs wind and a slope; may NOT burn off with the sun.
STEAM fog - COLD air moving over WARM water; the water evaporates and immediately condenses. Creates low-level turbulence and icing risk.
ICE FOG forms below about -25 F.
The instructor filmed upslope fog forming and dissipating in 10-15 minutes on Humphreys Peak.
Cloud families and what they signal 1:04:11
Clouds are classified by height, shape and characteristics, and reveal the stability of the air mass that formed them.
LOW - stratus, stratocumulus, nimbostratus. Formed in STABLE moist air, little vertical development.
MIDDLE - altocumulus, altostratus. Indicate significant turbulence aloft.
HIGH - cirrus, cirrostratus, cirrocumulus. Contain ICE crystals.
VERTICAL - towering cumulus and CUMULONIMBUS. Cumulonimbus carries the GREATEST turbulence of any cloud, plus rain, lightning and possible hail.
"NIMBO" or "NIMBUS" in a name means RAIN. "CUMULUS" means heaped/puffy.
LENTICULAR clouds - almond or lens shaped, form over mountains, and indicate severe turbulence with winds of 50 knots or more. The instructor notes these DO appear on the exam.
Sky cover and visibility 1:08:47
Sky cover is reported in EIGHTHS of the sky. CEILING means the lowest BROKEN or OVERCAST layer - few and scattered layers are NOT ceilings.
CLR / SKC - clear.
FEW - 1/8 to 2/8.
SCATTERED - 3/8 to 4/8.
BROKEN - 5/8 to 7/8.
OVERCAST - 8/8.
Visibility is horizontal and always reported in STATUTE miles, maximum 10, in quarter-mile increments down to less than a quarter.
Part 107 requires 3 statute miles; the instructor would reconsider a mission at 5.
Air mass stability 1:11:43
Stability is an air mass's resistance to vertical motion, governed by the LAPSE RATE - how fast it cools as it is lifted relative to its surroundings.
UNSTABLE (warm, moist - Florida in summer) - cumuliform cloud, SHOWERY precipitation, rough turbulent air, but GOOD visibility.
STABLE (cool, dry, or layered - Seattle) - stratiform cloud and fog, CONTINUOUS precipitation, smooth air, but POOR visibility.
Good visibility in unstable air is counter-intuitive but follows from the air being constantly mixed.
The full treatment is the adiabatic lapse rate, which the instructor deliberately leaves outside the course.
Thunderstorm ingredients and life cycle 1:16:16
Three ingredients are required - WATER VAPOUR, an UNSTABLE LAPSE RATE, and a LIFTING ACTION.
CUMULUS stage - building cloud, dominated by updrafts.
MATURE stage - the most dangerous; precipitation reaches the ground, updrafts and downdrafts coexist, lightning present.
DISSIPATING stage - downdrafts dominate and the cell collapses.
Rain reaching the ground is the marker that the cell has reached maturity.
Fronts 1:18:31
The boundary between two large air masses of differing characteristics. Passage brings a change in TEMPERATURE and a change in WIND DIRECTION.
WARM front - red rounded symbols. Gradual lift produces high cirrus well ahead, then nimbostratus with steady rain.
COLD front - blue triangles ('pokey like cold'). Acts like a snowplough, forcing rapid lift and CUMULONIMBUS with thunderstorms.
STATIONARY front - neither air mass advancing.
OCCLUDED front - a faster cold front overtakes a warm front, combining both weather patterns. The worst case.
A SQUALL LINE is a band of thunderstorms associated with a cold front.
Structural icing 1:22:21
Ice accumulating on the airframe when flying through VISIBLE MOISTURE at temperatures at or below freezing.
Two conditions required - visible moisture AND a surface at or below 0 C.
Ice on propellers changes their weight and lift, creating destructive vibration.
Moisture and electronics are a bad combination independent of the aerodynamics.
Every concept, three clicks deep
The same concepts as a quick reference: the closed row is the glance, open is the study card, and every timestamp jumps into the recording.
01Atmospheric composition and the troposphereThe atmosphere is roughly 78% nitrogen, 21% oxygen and 1% other gases.0:04:15›
The atmosphere is roughly 78% nitrogen, 21% oxygen and 1% other gases. Weather occurs in the TROPOSPHERE, the lowest layer.
Temperature decreases about 2 degrees CELSIUS per 1,000 ft of climb. Memorise this.
Airliners cruise around 35,000-40,000 ft partly to fly ABOVE most weather.
Uneven solar heating of the earth drives all air movement - warm air rises, cold air sinks - producing both global and local circulation.
An AIR MASS is a volume of air with uniform temperature and characteristics.
02Atmospheric pressure and its unitsPressure is the weight of air molecules on a unit area.0:08:15›
Pressure is the weight of air molecules on a unit area. Standard sea level pressure is 14.7 psi, 29.92 inches of mercury, or 1013.2 millibars / hectopascals.
Pressure decreases about 1 INCH OF MERCURY per 1,000 ft.
At 18,000 ft the pressure is about HALF the sea level value.
Inches of mercury comes from the mercury barometer - more pressure pushes the column higher.
Metric reporting uses hectopascals/millibars; 1013.2 hPa equals 29.92 inHg.
03The standard dayA reference condition of 15 degrees C (59 F) and 29.92 inHg AT SEA LEVEL, against which all aircraft perfor…0:11:26›
A reference condition of 15 degrees C (59 F) and 29.92 inHg AT SEA LEVEL, against which all aircraft performance is calculated.
Warmer than standard, or lower pressure than standard, both DEGRADE performance.
The standard values change with elevation - at 5,000 ft the standard is 5 degrees C and 24.92 inHg.
Manufacturer performance data assumes standard conditions.
04Pressure altitudeAltitude corrected for NON-STANDARD PRESSURE - the height above the 29.92 inHg reference plane.0:19:46›
Altitude corrected for NON-STANDARD PRESSURE - the height above the 29.92 inHg reference plane.
Formula (not required for the exam) - (29.92 - current altimeter setting) x 1,000 + field elevation.
Worked example - field at 5,000 ft with altimeter 29.79 gives 5,130 ft pressure altitude.
Low pressure raises pressure altitude (worse performance); high pressure lowers it.
IMPORTANT - reported altimeter settings are CORRECTED TO SEA LEVEL. A 5,000 ft field reporting 29.92 actually has about 24.92 inHg of real pressure outside. The reporting convention exists for manned aircraft altimeters.
05Density altitude - the number that actually mattersPressure altitude corrected for NON-STANDARD TEMPERATURE.0:25:49›
Pressure altitude corrected for NON-STANDARD TEMPERATURE. It is the altitude at which the aircraft performs as though it were flying.
Formula (not required) - (local temp C - standard temp C at that altitude) x 120 + pressure altitude.
Worked example - pressure altitude 3,000 ft, OAT 12 C. Standard at 3,000 ft is 15 - 6 = 9 C. (12 - 9) x 120 + 3,000 = 3,360 ft density altitude.
Sea level illustration - standard day gives 0 ft; 35 C gives about 2,400 ft; -5 C with 30.92 inHg gives about MINUS 3,400 ft; 35 C with 28.92 gives about 3,400 ft.
At a 5,000 ft field - hot and low pressure can feel like 8,400 ft; cold and high pressure like 1,600 ft.
The naming trap - HIGH pressure means HIGH air density but LOW density altitude, which is GOOD. Read 'density altitude' as one hyphenated word.
06What high density altitude actually degradesEvery performance parameter suffers as density altitude rises.0:33:13›
Every performance parameter suffers as density altitude rises.
Longer TAKEOFF and LANDING distances (fixed wing) - a familiar short strip may become too short.
Reduced RATE OF CLIMB - obstacle clearance may no longer work.
Lower service CEILING - the aircraft may not reach the altitude you need.
Reduced PAYLOAD capacity.
Reduced RANGE and endurance, and worse fuel or battery economy.
Lower achievable SPEED, and degraded manoeuvrability and stability - the "mushy" feel the instructor describes at 12,000 ft.
Lower humidity is better than higher humidity, though the effect is smaller and rarely charted.
07Wind, pressure gradient and isobarsWind is HORIZONTAL air movement, caused by air flowing from high pressure toward low pressure.0:36:40›
Wind is HORIZONTAL air movement, caused by air flowing from high pressure toward low pressure. Isobars are lines of equal pressure.
CLOSELY spaced isobars mean a steep pressure gradient and STRONG wind; widely spaced isobars mean light wind. The instructor's ski-slope analogy.
In the northern hemisphere - HIGH pressure circulates CLOCKWISE and OUTWARD; LOW pressure circulates COUNTERCLOCKWISE and INWARD.
High pressure pushes weather away and generally brings good conditions; low pressure draws air in and lifts it, generally bringing poor conditions.
Isobars are labelled in millibars.
08Convective currents and terrain effectsConvective currents are VERTICAL air movements driven by uneven surface heating.0:41:23›
Convective currents are VERTICAL air movements driven by uneven surface heating.
Rock, sand, barren ground and paved parking lots reflect heat and create UPDRAFTS.
Water, trees and vegetation absorb heat and produce DOWNDRAFTS.
Crossing from a parking lot to a lake produces a lift then a sink - the instructor could count down his students' approach every hot afternoon.
Buildings deflect wind; expect sudden gusts at street corners and between towers.
On the LEE side of a mountain, wind curls DOWNWARD - it can push a drone into the slope faster than it can climb out.
09Sea breeze and land breezeCoastal daily wind reversal driven by the different heating rates of land and water.0:46:04›
Coastal daily wind reversal driven by the different heating rates of land and water.
SEA BREEZE (day) - land heats faster, air rises over land, cooler air flows in FROM the water.
LAND BREEZE (night) - land cools faster, water stays warmer, flow reverses and moves OUT toward the water.
Operational risk - a land breeze pushes you offshore easily and then you must fight it home on a depleted battery.
10Low-level wind shear and microburstsA sudden, drastic change in wind speed and/or direction over a very short distance.0:48:20›
A sudden, drastic change in wind speed and/or direction over a very short distance. A microburst is a concentrated, violent downdraft.
Microbursts last roughly 5-15 minutes, produce downdrafts up to 6,000 ft per minute, and wind changes of 30 to 90 knots.
Associated with THUNDERSTORMS - the main reason not to fly near one.
The three-stage encounter - headwind (performance increases), then downdraft (forced down), then tailwind (performance collapses and you cannot return).
It can occur in dry air with no visible rain shaft.
11Temperature, dew point and saturationThe DEW POINT is the temperature to which air must be cooled to become SATURATED - holding all the water va…0:51:07›
The DEW POINT is the temperature to which air must be cooled to become SATURATED - holding all the water vapour it can. Fog and cloud are visible moisture formed when air reaches its dew point.
The CLOSER the temperature and dew point, the more likely fog, cloud, dew, frost or precipitation.
Fog IS cloud - the only difference is height above the surface.
Both values appear in ATIS, AWOS, ASOS and METAR reports.
The water-bottle analogy - once full, any more water spills out as condensation.
12FrostForms when the dew point is BELOW FREEZING and the collecting surface is also below freezing.0:54:37›
Forms when the dew point is BELOW FREEZING and the collecting surface is also below freezing.
Ice on propellers creates severe vibration, can destroy motors and bring the aircraft down.
Another reason not to fly in visible moisture - beyond the 3 statute mile visibility rule.
13Four ways air reaches saturationAll four involve COOLING an air mass to its dew point.0:56:10›
All four involve COOLING an air mass to its dew point.
Warm air moving over a COLD SURFACE.
A warm air mass COLLIDING with a cold air mass.
Ambient temperature falling at NIGHT with the air mass in place.
An air mass being LIFTED, cooling at about 2 degrees C per 1,000 ft.
14The four types of fogFog classified by the mechanism that cooled the air to its dew point.0:58:12›
Fog classified by the mechanism that cooled the air to its dew point.
RADIATION fog - ground cools rapidly overnight, chilling still air above. Needs LITTLE or NO wind, forms in valleys, burns off with morning sun.
ADVECTION fog - warm moist air moves over a colder surface. Needs WIND (up to about 15 knots). Common in coastal areas.
UPSLOPE fog - air pushed up rising terrain cools as it climbs. Needs wind and a slope; may NOT burn off with the sun.
STEAM fog - COLD air moving over WARM water; the water evaporates and immediately condenses. Creates low-level turbulence and icing risk.
ICE FOG forms below about -25 F.
The instructor filmed upslope fog forming and dissipating in 10-15 minutes on Humphreys Peak.
15Cloud families and what they signalClouds are classified by height, shape and characteristics, and reveal the stability of the air mass that f…1:04:11›
Clouds are classified by height, shape and characteristics, and reveal the stability of the air mass that formed them.
LOW - stratus, stratocumulus, nimbostratus. Formed in STABLE moist air, little vertical development.
MIDDLE - altocumulus, altostratus. Indicate significant turbulence aloft.
HIGH - cirrus, cirrostratus, cirrocumulus. Contain ICE crystals.
VERTICAL - towering cumulus and CUMULONIMBUS. Cumulonimbus carries the GREATEST turbulence of any cloud, plus rain, lightning and possible hail.
"NIMBO" or "NIMBUS" in a name means RAIN. "CUMULUS" means heaped/puffy.
LENTICULAR clouds - almond or lens shaped, form over mountains, and indicate severe turbulence with winds of 50 knots or more. The instructor notes these DO appear on the exam.
16Sky cover and visibilitySky cover is reported in EIGHTHS of the sky.1:08:47›
Sky cover is reported in EIGHTHS of the sky. CEILING means the lowest BROKEN or OVERCAST layer - few and scattered layers are NOT ceilings.
CLR / SKC - clear.
FEW - 1/8 to 2/8.
SCATTERED - 3/8 to 4/8.
BROKEN - 5/8 to 7/8.
OVERCAST - 8/8.
Visibility is horizontal and always reported in STATUTE miles, maximum 10, in quarter-mile increments down to less than a quarter.
Part 107 requires 3 statute miles; the instructor would reconsider a mission at 5.
17Air mass stabilityStability is an air mass's resistance to vertical motion, governed by the LAPSE RATE - how fast it cools as…1:11:43›
Stability is an air mass's resistance to vertical motion, governed by the LAPSE RATE - how fast it cools as it is lifted relative to its surroundings.
UNSTABLE (warm, moist - Florida in summer) - cumuliform cloud, SHOWERY precipitation, rough turbulent air, but GOOD visibility.
STABLE (cool, dry, or layered - Seattle) - stratiform cloud and fog, CONTINUOUS precipitation, smooth air, but POOR visibility.
Good visibility in unstable air is counter-intuitive but follows from the air being constantly mixed.
The full treatment is the adiabatic lapse rate, which the instructor deliberately leaves outside the course.
18Thunderstorm ingredients and life cycleThree ingredients are required - WATER VAPOUR, an UNSTABLE LAPSE RATE, and a LIFTING ACTION.1:16:16›
Three ingredients are required - WATER VAPOUR, an UNSTABLE LAPSE RATE, and a LIFTING ACTION.
CUMULUS stage - building cloud, dominated by updrafts.
MATURE stage - the most dangerous; precipitation reaches the ground, updrafts and downdrafts coexist, lightning present.
DISSIPATING stage - downdrafts dominate and the cell collapses.
Rain reaching the ground is the marker that the cell has reached maturity.
19FrontsThe boundary between two large air masses of differing characteristics.1:18:31›
The boundary between two large air masses of differing characteristics. Passage brings a change in TEMPERATURE and a change in WIND DIRECTION.
WARM front - red rounded symbols. Gradual lift produces high cirrus well ahead, then nimbostratus with steady rain.
COLD front - blue triangles ('pokey like cold'). Acts like a snowplough, forcing rapid lift and CUMULONIMBUS with thunderstorms.
STATIONARY front - neither air mass advancing.
OCCLUDED front - a faster cold front overtakes a warm front, combining both weather patterns. The worst case.
A SQUALL LINE is a band of thunderstorms associated with a cold front.
20Structural icingIce accumulating on the airframe when flying through VISIBLE MOISTURE at temperatures at or below freezing.1:22:21›
Ice accumulating on the airframe when flying through VISIBLE MOISTURE at temperatures at or below freezing.
Two conditions required - visible moisture AND a surface at or below 0 C.
Ice on propellers changes their weight and lift, creating destructive vibration.
Moisture and electronics are a bad combination independent of the aerodynamics.
Tools referenced
| Tool | Coverage | Moment | Context |
|---|---|---|---|
| Advisory Circular 00-6, Aviation Weather | mentioned | 0:00:00 | The instructor's own source for these slides; the deep reference if you want the full theory. |
| Pilot's Handbook of Aeronautical Knowledge, chapter 12 | mentioned | 0:00:00 | Standard weather chapter. |
| FAA-H-8083-22 Remote Pilot Study Guide, chapter 3b | mentioned | 0:00:00 | Weather effects on sUAS performance. |
Session materials
Archived locally on V: — click to open. Companion pages link to the LMS.
Action items
Resources mentioned
- docAudio review - Weather (MP3) 1:23:55
Extraction notes
This page was built from an auto-generated transcript, which garbles product and people's names. Those were corrected silently in everything above and logged here for transparency. The warnings flag claims that were true on the recording day but change fast.
Transcript corrections applied
| The transcript says | The trainer actually means |
|---|---|
| FA / EFA | FAA |
| PHAK / p-hack | Pilot's Handbook of Aeronautical Knowledge |
| AVI / Aviation Weather | Advisory Circular 00-6, Aviation Weather |
| ADIZ (in weather context) | ATIS - the weather broadcast, not the air defense identification zone |
| a was / AWAS | AWOS (Automated Weather Observing System) |
| eviction fog | ADVECTION fog |
| nimbo stratus / nimble clouds | nimbostratus |
| cirrus cumulus | cirrocumulus |
| three-statute malvisibility | three statute mile visibility |
| 2 degrees every 1,000 feet | correct - but note it is degrees CELSIUS |
| 2999 / 2992 / 29.92 | 29.92 inches of mercury |
| lance-shaped cloud | lens-shaped (lenticular) |
| condensate | condense |
True on recording day — verify before relying
- Standard atmosphere values, lapse rates, fog classifications, cloud families, thunderstorm stages and front types. - STATUS: STABLE physical science; unchanged and not subject to regulatory drift.
- The density altitude and pressure altitude formulas. - STATUS: Approximations taught for intuition. The instructor states twice they are NOT required for the exam. Use a published density altitude calculator operationally.
- "2 degrees per 1,000 ft" lapse rate. - STATUS: Standard approximation (actual ICAO value is 1.98 C). Fine for the exam.