NS433 ~ aviation practicum 12 weeks
what are the following lapse rates: Average/Standard Lapse Rate Shallow Lapse Rate Steep Lapse Rate Isothermal Lapse Rate Inversion Lapse Rate
Average/Standard Lapse Rate = 2°C (3.5°F) per 1000 ft Shallow Lapse Rate = between 1.5 to 3.0°C / 1000 ft Steep Lapse Rate = > 3°C / 1000 ft Isothermal Lapse Rate - Indicates temperature is the same at different altitudes Inversion Lapse Rate - Temperature increases with increasing altitude (occurs in the stratosphere) Can be anywhere from a few hundred to a few thousand feet thick.
how do you identify the tropopause in flight?
Avg. height of 36,000 ft MSL over U.S. Anvil tops of thunderstorms with spread out over base of tropopause Haze layer with a definite top.
What three ways can you identify the tropopause in flight?
-isothermal: temperature is constant -avg height of 36000ft MSL over US -anvil tops of thunderstorms will spread out over top of tropopause -haze layer with a definite top
_____in-Hg pressure changes = ___ ft of altitude changes
0.1 in-Hg pressure changes = 100 ft of altitude changes
draw and label the day time sea breeze picture.
<insert day sea breeze pic>
label and describe a gradient wind picture
<insert gradient wind pic>
draw and label a picture of daytime mountain and valley winds
<insert pic of mountain and valley winds>
draw and label a picture of night land breeze.
<insert pic of night breeze>
label a pressure gradient picture
<insert pic of pressure gradient>
label a station model.
<insert pic of station model>
draw and label the altitude picture with: absolute altitude pressure altitude true altitude sea level pressure standard datum plane
<insert pic of the diff altitudes>
label and diagram the atmospheric layers picture
<insert pic>
label a pressure chart
<insert pressure chart pic>
temperature and altimeter picture:
<insert temp pic>
what are the different station models?
<station model pic>
A 1000 ft increase in altitude will result in a pressure decrease of ____________ in-Hg and temp decrease of _______________ ?
A 1000 ft increase in altitude will result in a pressure decrease of approx. 1 in-Hg and temp decrease of 2°C (3.5°F).
how do we avoid problems with changing temperature and altitude readings?
Aircrews must update their altimeter setting to avoid problems! Updates sent via ATC 0.1 in-Hg pressure changes = 100 ft of altitude changes Very important to receive a current altimeter setting at destination prior to landing!
Altimeters calibrated for ___________________. Incorrect altitude indications will result if ____________ deviates from the standard.
Altimeters calibrated for standard lapse rate. Incorrect altitude indications will result if temperature deviates from the standard.
29.92 is the what????/ **** how do altimeters work and what are some potential trouble spots?
Altimeters operate using outside pressure Can be subject to mechanical failures: installation problems misalignment static port positioning
what is altitude and what is used to measure it?
Altitude - Height above a given reference. Displayed by an altimeter in an aircraft Barometric Altimeter - Calibrated to display altitude in feet instead of pressure in inches of mercury.
As sea level pressure on the surface decreases, the whole column of air aloft is _______, causing an aircraft flying at an assigned MSL altitude to _______ to a ______ AGL altitude.
As sea level pressure on the surface decreases, the whole column of air aloft is lowered, causing an aircraft flying at an assigned MSL altitude to descend to a lower AGL altitude.
what is atmospheric (barometric) pressure?
Atmospheric (Barometric) Pressure - Pressure exerted on a surface by the atmosphere due to the weight of the column of air directly above that surface. Avg. weight of air on a square inch of the Earth's surface at sea level under standard conditions is 14.7 pounds.
what wind speeds does the jet stream average?
Average 100-150 knots, but may exceed 250 knots Stronger in some places than in others; rarely encircles the entire hemisphere Average height is approx. 30,000 ft MSL (depending on latitude and the season) Winter → jet stream is further south and is faster than summer
what is the altitude/ height of the jet stream?
Average height is approx. 30,000 ft MSL (depending on latitude and the season)
Average/Standard Lapse Rate = __°C (____°F) per _______ ft
Average/Standard Lapse Rate = 2°C (3.5°F) per 1000 ft
What is the Standard Lapse Rate?
Average/Standard Lapse Rate = 2°C (3.5°F) per 1000 ft
what are the sayings for MSL pressure changes?
"High to Low, Look Out Below!" "Low to High, Plenty of Sky!"
what is the coriolis force?
Coriolis Force - Earth's rotation diverts air to the right, with respect to its initial direction of motion, regardless of whether the air is near a high or low pressure system. Coriolis Force, plus pressure gradients, creates gradient winds
DA is not used as a ___________. Instead, it is used as an index for _______________.
DA is not used as a height reference. Instead, it is used as an index for aircraft performance. High DA = less performance thrust reduced due to less air mass to compress thinner air results in less lift available result in longer takeoff and landing distances reduced rate of climb
how does the daytime affect mountain and valley winds?
Day: Mountain slopes heated by sun's radiation; in turn, they heat the adjacent air through conduction. Air becomes warmer than the air farther away from the slope at the same altitude. Warmer air begins to rise, and cools as it moves away from the warm ground. As it moves away, it increases density and settles downward toward valley floor. Valley Wind - Downward motion forces warmer air near the ground to rise up the mountain from the valley
how does daytime conditions impact sea and land breeze?
Day: Pressure over warm land becomes lower than over the colder water. Colder air over the water moves toward the lower pressure, replacing the warm air over the land that moves upward.
what is density altitude?
Density Altitude (DA) - Pressure altitude corrected for nonstandard temperature deviations. Ex: On a hot day, the air is less dense, which increases DA. In this situation, the DA of an airfield would be higher than both the published field elevation and PA. Vice versa is true on a cold day.
Federal Aviation Rules (FAR) require all aircraft flying above __________ ft MSL set ______ in altimeter.
Federal Aviation Rules (FAR) require all aircraft flying above 18,000 ft MSL set 29.92 in altimeter.
how does flying around the jet stream impact planning?
Flying around the jet stream requires additional aircrew flight planning consideration. Greater headwind component for westerly-traveling aircraft will increase fuel consumption and may require alternate landing fields along the route.
For every __°C that the temp varies from the standard, the altimeter will be in error by ___%.
For every 11°C that the temp varies from the standard, the altimeter will be in error by 4%.
what is the atmosphere?
Gaseous covering of the Earth. Envelope of air rotates with the Earth, but also has continuous motion relative to the Earth's surface, called circulation. Created primarily by the large temperature differences between the tropics and the polar regions.
what type of weather is associated with ridges and high areas on pressure charts?
Good weather generally associated with ridges and high areas.
what are gradient winds?
Gradient Winds - Flow perpendicular to the pressure gradient force Flow parallel to isobars Clockwise around high pressure areas Counterclockwise around low pressure areas Found above 2,000 ft AGL
what is height above ground level?
Height Above Ground Level (AGL) - Height above the terrain directly beneath aircraft. Calculated by subtracting terrain elevation from true altitude. Also displayed by radar altimeter in the cockpit. Sometimes called "absolute altitude".
if you have a high DA, what does that indicate about aircraft performance?
High DA = less performance thrust reduced due to less air mass to compress thinner air results in less lift available result in longer takeoff and landing distances reduced rate of climb At some high DAs, takeoffs and/or single-engine flight might not be possible due to thrust/lift limitations
define the following features of pressure charts: High Pressure Areas Low Pressure Areas Ridge Trough
High Pressure Areas - Pressure in the center higher than surrounding areas. "Mountain" Low Pressure Areas - Pressure in the center lower than surrounding areas. "Basin/Valley" Ridge - Extension of a high pressure area. Trough - Extension of a low pressure area.
If air is colder than the standard atmosphere, the aircraft will be ______ than indicated. If air is warmer that the standard atmosphere, the aircraft will be _________ than indicated.
If air is colder than the standard atmosphere, the aircraft will be lower than indicated. If air is warmer that the standard atmosphere, the aircraft will be higher than indicated.
If an aircraft flies from one place to another at a constant indicated altitude, it is flying along a ______________________.
If an aircraft flies from one place to another at a constant indicated altitude, it is flying along a surface of constant pressure.
If flight path takes you into an area of higher MSL pressure, the aircraft will be _________ than the altimeter indicates.
If flight path takes you into an area of higher MSL pressure, the aircraft will be higher than the altimeter indicates.
If flight path takes you into an area of lower MSL pressure, the aircraft will be ___________ than the altimeter indicates.
If flight path takes you into an area of lower MSL pressure, the aircraft will be lower than the altimeter indicates.
If wind is at your back, the area of lower pressure will be at your ________
If wind is at your back, the area of lower pressure will be at your left
what is the stratosphere?
Increasing temp with increasing altitude. Flight in the stratosphere is generally smooth with excellent visibility. Air is thin and offers little resistance to aircraft. General lack of weather, which makes for excellent flying.
Isobar spacing represents the _____________.
Isobar spacing represents the Pressure Gradient Force (PGF)
what is the jet stream?
Jet Stream - Narrow band of strong winds of 50 knots or more that meanders vertically and horizontally around the hemisphere in wave-like patterns Wind speeds generally increase with altitude through the troposphere, reaching maximum speed near the tropopause and culminating in the jet stream
What is a Kollsman Window and what do aircrews use it for?
Kollsman Window - Shows the reference pressure to determine the height number. "Altimeter Setting" = set to indicate true altitude at field elevation 29.92 in-HG = standard (mean sea level)
what is the kollsman window? (altitude)
Kollsman Window - Shows the reference pressure to determine the height number. "Altimeter Setting" = set to indicate true altitude at field elevation 29.92 in-HG = standard (mean sea level)
what is a land breeze?
Land Breeze - The resulting onshore wind blowing from the land Not as strong as sea breezes
Land normally ________ than the ocean during the day. Land normally ________ than the ocean during the night.
Land normally warmer than the ocean during the day. Land normally colder than the ocean during the night.
Define Lapse Rate.
Lapse Rate - Decrease in atmospheric temperature with increasing altitude.
what is lapse rate?
Lapse Rate - Decrease in atmospheric temperature with increasing altitude.
What is the troposphere?
Layer adjacent to the Earth's surface. Varies in height: Avg. of 55,000 ft over equator Avg. of 28,000 ft over poles Temperature normally decreases with increasing altitude. Large amounts of moisture and condensation nuclei. Nearly all weather occurs here. Winds increase with altitude (over 200 knots may occur near top of troposphere).
define mean sea level pressure:
Mean Sea Level (MSL) - Measured directly at sea level, or calculated using the standard pressure lapse rate. Used as the reference level for surface analysis charts "True Altitude" = actual height above MSL
What are pressure charts?
Meteorologists track different weather systems by noting pressure changes Horizontal distribution of pressure across the Earth is depicted on weather charts by "isobars" (lines of equal barometric pressure)
what is mountain wind?
Mountain Wind - Dense air flows down the mountain.
how does nighttime impact mountain and valley winds?
Night: Air at the mountain slope is cooled by outgoing radiation and becomes more dense. Mountain Wind - Dense air flows down the mountain.
what type of weather is associated with troughs and low areas on pressure charts?
Poor weather generally associated with troughs and low areas.
what is pressure altitude?
Pressure Altitude (PA) - Height above the standard datum plane. Standard Datum Plane - Actual elevation above/below earth's surface at which the barometric pressure is 29.92 in-Hg. Federal Aviation Rules (FAR) require all aircraft flying above 18,000 ft MSL set 29.92 in altimeter.
what is the pressure gradient on charts?
Pressure Gradient - Rate of pressure change in a direction perpendicular to the isobars (horizontal distance). Isobar spacing represents the Pressure Gradient Force (PGF) Steep/Strong → when isobars close together Shallow/Weak → when isobars far-apart Steeper the gradient → stronger the winds
how is a night breeze formed?
Pressure over warm water becomes lower than over the colder land. Colder air over the land moves toward the lower pressure, replacing the warm air over the water that moves upward.
what are sea and land breezes?
The differences in specific heat of land and water cause land surfaces to warm and cool more rapidly than water surfaces. In coastal areas, this difference of temperature creates a tendency for the warmer, less dense air to rise, and the cooler, more dense air to sink, which produces a pressure gradient.
What is a trough and what type of weather is generally associated with it?
Trough - Extension of a low pressure area. Poor weather generally associated with troughs and low areas.
The stratosphere is excellent for flying. (T / F)...Why?
True, general lack of weather
what is valley wind?
Valley Wind - Downward motion forces warmer air near the ground to rise up the mountain from the valley
what are flight levels and how are they communicated?
When aircraft fly pressure altitudes, they are assigned a flight level (FL) of three digits, representing feet above 29.92. Ex: "Fly flight level two five zero" fly so that the altimeter reads 25,000 ft with 29.92 set
what is wind shear?
Wind Shear - rapid change in wind speed or direction over a short horizontal distance, which can result in lift and altitude changes
Wind direction always expressed in terms of __________ _____________.
Wind direction always expressed in terms of direction from which it is blowing.
Wind flows ________, or almost ________, to isobars. Wind flows _________ around high pressure. Wind flows ____________ around low pressure.
Wind flows parallel, or almost parallel, to isobars. Wind flows clockwise around high pressure. Wind flows counterclockwise around low pressure.
how does wind flow on surface analysis charts?
Wind flows parallel, or almost parallel, to isobars. Wind flows clockwise around high pressure. Wind flows counterclockwise around low pressure.
how do seasons impact the jet stream?
Winter → jet stream is further south and is faster than summer
when flying toward lower MSL pressure:
altimeter: indicates higher than actual actual MSL altitude: lower than indicated by the altimeter High Pressure to Lower Pressure: MSL = (Assigned Altitude) - (Altitude Error) AGL = (MSL) - (Field Elevation) Indicated Altitude on Deck = (Field Elevation) + (Altitude Error)
atmospheric circulation moves air in mainly two ways:
ascending currents descencing currents both produce winds
when flying toward higher MSL pressure:
atimeter: indicates lower than actual actual MSL altitude: higher than indicated by the altimeter Low Pressure to Higher Pressure: MSL = (Assigned Altitude) + (Altitude Error) AGL = (MSL) - (Field Elevation) Indicated Altitude on Deck = (Field Elevation) - (Altitude Error)
If ATC directed you to fly flight level 190, what altitude would you fly?
fly so that the altimeter reads 19,000 ft with 29.92 set
when flying in low temperature/moisture:
higher air density lower density altitude increased thrust and lift shorter takeoffs and landings
what happens to temperature in the toposphere?
it decreases
where do the strongest winds (jet stream) occur?
just below the tropopause
What is an isobar?
line of constant pressure on a pressure chart
when flying in high temperature/moisture:
lower air density higher density altitude decreased thrust and lift longer takeoffs and landings
what are the layers of the atmosphere?
space ^ exosphere thermosphere mesosphere stratosphere troposphere earth >
what happens to the temperature in the tropopause?
the temperature stays consistent.
In which atmospheric layer does nearly all weather occur?
toposphere
what atmospheric layer does most weather occur?
toposphere
what layer of the atmosphere is the coldest?
tropopause
If your flight path takes you into an area of higher MSL pressure, the aircraft will be higher/lower than the altimeter indicates?
when flying toward higher MSL pressure: atimeter: indicates lower than actual actual MSL altitude: higher than indicated by the altimeter
what happpens to wind in the troposphere?
wind increases
what is the tropopause?
Boundary between troposphere and tropopause is marked by an abrupt change in rate of temp. decrease with increasing altitude. Transition zone between troposphere and stratosphere. Temp. is consistent with altitude. Strongest winds (jet stream) occur just below tropopause. Moderate to severe turbulence and wind shear. Normally coldest area within lower atmosphere. Severe thunderstorms may penetrate tropopause into stratosphere.
what is buy's ballot law?
Buy's Ballot Law - If wind is at your back, the area of lower pressure will be at your left When standing on the Earth's surface, the low will be slightly forward or directly left because wind flows across the isobars Used as a Rule of Thumb!
what is sea breeze?
Sea Breeze - The resulting onshore wind blowing from the sea (15-20 knots) Seldom penetrate far inland
what does the spacing of isobars indicate?
Spacing of isobars indicates the rate of pressure change over a horizontal distance.
what is a standard day? (with regards to atmospheric pressure)?
Standard Day - Used for a standard reference in Naval Aviation. Sea level = 29.92 in-Hg and 15°C (59°F) A 1000 ft increase in altitude will result in a pressure decrease of approx. 1 in-Hg and temp decrease of 2°C (3.5°F).
what are station models?
Station Models - Display information to provide max amount of data in minimum space.
define station pressure:
Station Pressure - Atmospheric pressure measured directly at an airfield or other station.
Steep/Strong → when isobars __________ Shallow/Weak → when isobars _____________ Steeper the gradient → _________the winds
Steep/Strong → when isobars close together Shallow/Weak → when isobars far apart Steeper the gradient → stronger the winds
what are surface winds?
Surface Winds - Winds below 2,000 ft AGL that take into account the role of surface friction Surface friction reduces wind speed, which causes a reduction of Coriolis Force
Takeoffs and landings are best performed into a ________.
Takeoffs and landings are best performed into a headwind.
