intro_to_aviation_block_3_20180401181931 Flashcards
under what height does 99% of weather occur
the lowest 35 000 of the atmosphere
under what height is the greatest concentration of water vapour (gas) is found. Water vapour changes state under normal atmospheric conditions to form clouds, fog and precipitation.
35 000
what four elements make up the atmosphere
- Nitrogen 78.09%, oxygen 20.95%, CO2 0.03%, Ozone 0.00003%, water vapour 0-3%
Where is water vapour
everywhere in the atmosphere
explain the process of water vapour changing state
for water vapour to change state very spall particles (sand, dust, smoke and salt) are present in the air, these particles are essential in the process of changing water vapour into liquid or solid.
What is the name for the particles entering the water vapour
These are called condensation nuclei or crystalation nuclei and could reduce visibility seriously
Explain the process of rain
- when the small particles bind with the water vapour, they bind with other particles, then gradually grow in size, they do this until they fall as rain
define air mobility
- Air does not occupy a fixed space because its molecules have a great deal of freedom of motion or mobility. Molecules of water also have a freedom of motion but they do not have such a high degree of mobility as air molecules have, air can be expanded and compressed almost limitlessly
Capacity for compression
- When air molecules are pack closely together because pressure increase, the density will increase friction between moving air molecules resulting in an increase in temperature
Capacity for expansion
- When air is permitted to expand due to decrease in pressure, the air molecules become more spaced and the density decreases, this will also decrease the friction between the air molecules, resulting in a decrease in temperature
Would cold or warm runway take more time to take off
a warm runway takes more time to take off (low density)
when air is forced to rise it reaches area of lower pressures so i expands and cools
no back just good shit to know
what is the lowest layer of the atmosphere called
the troposphere
what is the second lowest layer of the atmosphere called
the tropopause
what is the thrd lowest layer of the atmosphere called
the stratosphere
what is the tropopause
the boundary layer between the troposphere and the stratosphere
explain how temperature works in the statosphere
temperature may remain reliably constant or actually increase with height or may increase due to chemical activity in the ozone layer
What is the average height of the tropopause
11 km but is much higher in warmer areas then it is in cold air
over the north pole the average height is ____
8 km
over the equator the height is
18 km
what is the temperature of the tropopause
10*C
what is the ICAO standard atmosphere guidlines
- air is perfectly dry gas- mean sea level pressure of 29.92- a mess sea level pressure of 29.92 inches of mercury- a rate of decrease of temperature with a height is 1.98 degrees per 1000 feet
when the temperature is higher then 15 C the true altitude of the aircraft will be____
higher
when the temperature is Lower then 15 C the true altitude of the aircraft will be____
Lower
What are the two basic cloud forms
Stratiform (horizontal layers)Cumuliform (rising currents)
What are the four types of clouds
Cumulus (Cu) Towering Cumulus (TCU)Cumulonimbus (CB) Altocumulus Castellanus (ACC)
What is the most dangerous cloud
CB Cumulonimbus
What is ACC
Altocumulus Casellanus, this is often a telltale sign of a thunderstorm development
Explain CU
Cumulus, Detached clouds generally dense with short outlines, developing vertically in the form of rising mounds, domes or towers of which the bulging upper part is often like a cauliflower.
Explain TCU
Towering Cumuls, another name for cumulus congests, it is a rapidly growing cumulus or an individual dome shaped clouds whose hight exceeds its width. often means showers below
Explain CB
Cumulonimbus, thundercloud, heaven and dense cloud, with considerable vertical extent, in the form of a mountain or huge tower.
Explain ACC
white or grey or both, patch sheet or layer of cloud, generally with shading composed of laminae, rounded masses, rolls etc
What is the impact on aviation for CU
bumpy flight beneath and in cloud, can develop into TCU and CB, updrafts below the cloud
What is the impact on aviation for
can be rough to very rough air, significant icing if above the freezing level, often develop into CB’s strong updrafts below and in cloud
What is the impact on aviation for
Thunderstorm activity. precipitation, winds, violent vertical currents. Hail often resent. Extreme turbulence. Extreme Icing and lightning (MOST DANGEROUS
What is the impact on aviation for
Turbulence, precipitation and icing
what is the abbreviation and code for clear
SKC 0/8
what is the abbreviation and code for few
FEW 2/8 or less
what is the abbreviation and code for scattered
SCT 3-4/8
what is the abbreviation and code for brocken
BKN 5,6 or 7/8
what is the abbreviation and code for overcast
OVC 8/8
what is the significance of ISOBARS
The distance between two lines identify a pressure difference of 4 hectopascals, either increasing or decreasing in value.
what is a trough
bulge in the side of a low pressure system
What is a ridge
A bulge in the side of a high pressure area
Explain buys ballot law
- in the northern hemisphere (canada), if you stand with you back to the wind, the area of low pressure is always to your left. (Left=Low)
what way does air blow around highs
clock wise
what way does air bow around lows
clock wise
how is weather formed in a low
Air is deflected by friction to the centre of a low, it accumulates and rises at the centre. As a result, at the centre of a low, air rises, expands, cools and then clouds form
What happens in regards to weather in a high
At the centre of a high the air flows out (towards low pressure), it sinks, heats and skies tend to be clearer.
How big is the diameter of a high
several hundred even thousands of kilometres in diameter. Clockwise
How big is the diameter of a low
Low pressure systems are generally sings of bad weather and cover from 10 km to hundred of kilometres in diameter.
What is pressure gradient
the rate of change of pressure with horizontal distance measured in kilometers (km). The speed of wind is directly proportional to the pressure gradient. The faster the pressure changes, the stronger will be the winds
What is steep pressure gradient
when the isobars are close together
What words are used to describe a low
Deep and shallow
What words are used to describe a high
Strong and weak
weather charts use the…
mean sea level pressure
What does ATIS stand for
automatic terminal information service
What is coriolis Force
- The air moving cause by the pressure gradient force is emmediately acted upon by another force which is due to the earths rotation. - if the earth wasn’t rotating wind would flow directly from high to low pressure areas
Does coriolis force create wind
no just moves t
what direction does coriolis force bend the air from the northern hemisphere to the equator
right
Friction at the surface and up to about 3000 feet cause the wind to,,,
- slow down2. flow into a low pressure area3. flow out of a high pressure area
what is veering
when a wind makes a change in a clockwise direction
what is backing
a backing is when wind makes a counter clockwise change in direction
on a surface map the wind blows towards,,,
the dot
what does the number of hooks signify on a surface map
each hook stands for 10 Knots , therefore half of a hook is 5Knots
what is wind shear
- A change in wind speed and or direction in a short distance. can be horizontal or vertical.- When two winds at different directions meet, it caused a shear.- Speed shear is two winds that are close together but different speeds.
What is the jet stream
- narrow band of exceedingly high wind speeds in the upper levels of the troposphere
How high is the jet stream
between 20 000 and 40 000 feet over canada
how does the jet stream change with season
it is higher in summer and lower in winter
what is the minimum wind speed of the jet stream
60 kt
how long is the jet stream
thousands of miles line
how wide is the jet stream
a few hundred mile wide
how thick is the jet stream
a few thousand feet thicc
how fast is the core of the jet stream
can reach 250 Knots, but generally ranges between 100 and 150 knots
relative humidity RO
the ratio of the amount of water vapour actually in the air compared to the maximum amount of water vapour actually in the air compared to the maximum amount of water vapour the air can hold at that particular temperature (expressed as a percentage)
Absolute humidity
he amount of water vapour contained in a unit of air (or the mass of water vapour (gm) / volume of air (m^3))
what temperature air can hold the most amount of water:- -20 C- 0 C- 20 C
20 degrees C, this is because the warmer the air the greater its capacity to hold moisture
does cold or warm air hold moisture better
warm air can hold more water then cold air can
in cold air…
water vapour molecules are closer together
In warm air…
water vapour molecules have more room
the Dew point is
the temperature expressed in degrees C, which air has to be cooled to achieve Saturation
what is air temperature symbolized by?
T
what is dew point symbolized by?
Td
what is stable air
- air that will resist upward or downward displacement, and tends to return to its original horizontal level, is said to be stable
what is unstable air
- air which tends to move further away (without additional lift) is said to be unstable.
what are some traits of stable air
- low visablilites, fog may occur- stratus type cloud- steady precipitation - consistent, steady winds- smooth flying conditions (often IFR with respect to ceiling and visibility)
What are some traits of unstable air
- good visibilities - vertical development type clouds- showery precipitation- gusty winds- bumpy flying conditions
What is a lifting agent
a force pushing air upwards
What is convection
air is headed from below contact with the earths surface. Rising columns of air (thermals) are usually separated separated by areas f sinking air.
What is orographic lift
ir is forced to rise (by the wind) up sloping terrain. Type of cloud depends on the stability of the lifted air
What is frontal lift
Air is forced to rise by a wedge of colder and denser air. Cold fronts are advancing cold air which undercuts the warm air. Warm front are retreating cold air and the warm air overruns the denser air.
What is mechanical turbulence
type of lift caused by friction between the air and the ground. The air is “mixed up” into a series of eddies. Mechanical turbulence depends on the strength of the wind and the roughness of the terrain
What is Convergence lift
occurs at the centre of a low pressure area, the air converges at this point and is forced to rise, created cloud and precipitation.
What are maritime air masses
air masses that have formed over a large body of water, air is humid
what are continental air masses
air mass that is formed over a large land area, air is usually dry
What are the three terms used to describe air over north americal
arctic, polar, and tropical
what is arctic air
for cold air mass, this air mass is formed in the arctic or high altitudes
what is polar air
for temperate air mass (permafrost line to 30 degrees north) this air mass is actual formed in temperate zones by heating of an arctic air mass or the cooling of a tropical air mass
what is tropical air
for warm air mass (30 degrees N south to the equator) is formed in the tropics or low attitudes
What are the four types of air masses in north america
Continiental arctic (in winter only) —- cAMaritime arctic — mAMaritime Polar — mPMaritime Tropical — mT
What are the two air masses that are rare in north america
Continental polar cP and contenental tropical can occur but are rare in north america
what are the three main factors that determine the weather in any given air mass
moisture content, the cooling precess and the stability of the air
if air is moist, cloud formation can only happen if the air is cooled, this happens when
- air being in contact with relatively colder ground cooling by radiation- advection of warm air over a colder serface- expansion brought about by a lifting process
When do air masses move
when they acquire the temperature and moisture characteristics of the underlying surface
is that a quick or slow process
slow
how many fronts can you see on a weather map in the winter time
three
how many fronts could you see on a weather map in the summer time
two
what happens to cold air masses when they oass over a much warmer air mass
heated from below and become more unstable. The same happens inversely Aswell
Define front
the transition zone between two air masses
what are the names of the two fronts that exist in the summer time
the maritime and polar fronts
during the winter season what are the three fronts
the arctic, maritime and polar fronts
what is the definition of a warm front
warm air moving on cold air causing warmer less dense air to rise
what is the definition of a cold from
cold air advances on warmer air ausing warm air to rise
on a map what do cold fronts look like
arrows
on a map what do warm fronts look like
semi circles
what do stationary fronts look like
they alternate between arrows and circles pointing in opposite directions
What are the 5 factors that determines the severity
- The slope of the frontal surface2. The speed of the front movement 3. the temperature of the lifted air mass4. the moisture content of the lifted air mass5. the stability of the lifted air mass
when does the temperature change when a warm front moves in
the temerature may change before the front arrives do to proximity of the warmth
what sometimes happens when a cold front approaches
sometimes a slight increase of temperature will happen because the cold front pushes the clouds out of the way so the suns rays can warm up.
Dew point temperature relative to fronts
as temperature changes with the passage of fronts, we can also expect a change in the moisture content of the air
When a warm front approaches the statism
precipitation will occur first
What is the slope of a cold front
usually 3 km to 150 km or 1:50
What is the slope of a warm front
Usually shallower, with an average ratio of 1:200
what does the shape of a warm front cause
causes you feeling the warmth earlier, causes a wide spread area of cloudiness
Precipitation at a warm front
The moisture content of the overrunning warm air. The stability of the overrunning warm air. The degree of overrunning (i.e. the pressure gradient in the warm air. and angle of warm air motion relative to the frontal surface).
Precipitation at a cold front
the factors that determine the type of cloud and precipitation are: The moisture content of the lifted warm air. The stability of the lifted warm air. The degree of lift: - the slope of the frontal surface. - the speed of the front.
If the warm air is moist and stable, then expect layer clouds in the following order as the front approaches your station
Cirrus. •Cirrostratus (halo is a classical indicator of an approaching warm front). •Altostratus. •Nimbostratus and •Continuous precipitation (stratus fractus and frontal fog forming in the precipitation).
