SAMRA (Meteorology) Flashcards
What is the approximate ceiling of the tropopause?
36,000ft
Where is the isothermal lapse rate in the stratosphere approximately:
65,000ft
What is an isothermal?
Where temperature is constant with height
What is the temperature at the tropopause?
-56.5 degrees
What is the lapse rate within the tropopause?
1.98 degrees per 1,000ft
Does mean sea level pressure change when it gets warmer but station altimeter remains the same?
When it becomes warmer at the station, the MSLP decreases due to the less dense air.
MSLP uses 12hr average temperature!!!!
How are isobars spaced out regarding pressure?
Each line is 0004 QNH from each other.
What causes highs and lows to form?
- Sudden changes in velocity (spin)
- Sudden accelerations and decelerations in wind speed (jet streaks)
Occurs high up in atmosphere
What forces act on the wind?
- Pressure gradient force (PGF)
- Coriolis force (CF)
- Friction
- Thermal wind gradient force (TWGF)
- Centrifugal forces around H & L (Cf)
What is an isotach?
Line of equal wind speed
For the same PGF, would the wind speed around a surface low be greater or less than a surface high?
HIGH PRESSURE WILL HAVE GREATER WIND SPEED
Because pressure gradient force goes inward on a low, and it goes outward on a high, going with the coriolis force!
If air mass is moist and stable with mechanical turbulence present in lower levels, what type of clouds can you expect to be present?
Stratus and stratocumulus
Fronts that affect Canada in general:
Continental arctic cA
Maritime arctic mA
Maritime polar mP
Maritime tropic mT
What is a front?
A transition zone between two air masses where temperature changes
What is a cold front:
Leading edge of an advancing cold air mass
What is a warm front:
Trailing edge of a retreating cold air mass
What is frontolysis:
Temperature contrast (difference) between two air masses decreases and front disappears (temps merge together)
What is frontogenesis:
Temperature contrast (difference) between two air masses increases and a front is formed
Factors affecting weather severity at cold front:
- Speed of front
- Moisture content of the WARM AIR MASS
- Stability of the WARM AIR MASS
environment in which the front exists matters most; i.e. where the cold front is moving towards
Where can squall lines exist ahead of a cold front?
100 to 200 NM ahead of the cold front
Remember bad weather always occurs in the warm air because it can hold more moisture; when you feel the pressure drop after a squall line, the conditions are going to get better
A fast moving cold front having a warm air mass that is moist and unstable could give rise to ___.
A squall line
What happens to wind, temperature and pressure as a cold front passes?
Temp decreases
Winds veer and increase
Pressure increases due to colder air being more dense
NOTE:
Temperature decrease may not begin for 2 to 3 hours after frontal passage
Surface wind tends to remain strong after cold front passage due to high pressure behind frontal wave!! i.e. that coriolis and PGF being higher around a high pressure
What happens to wind, temperature and pressure as a warm front passes?
Temperature increases
Winds veer and increase (same as cold front)
Pressure decreases
Temperature may not begin to warm for 2 to 3 hours after frontal passage
A cold front with a steep frontal surface is approaching your location; frontal passage has occurred. has WX passed, occurring now or yet to arrive?
Yet to arrive; something to do with steep frontal passage
What is a trough?
An area of low pressure; GFA labeled as a purple dotted line
double lined purple line on GFA indicates a higher level trough
What is a trowal?
troWAL (warm air aloft), depicted as red and blue “T” on GFA
SAME AS OCCUDED FRONT
What happens to OAT as you fly through a TROWAL?
Rise than fall!
How can you tell which wind direction a mature frontal wave will move?
It will move parallel to the isobars in the warm sector!
Under what altitude does the affects of surface friction affect wind speed/direction?
2000-3000ft AGL (air backs and decrease around a high AND a low on exam
When flying above freezing level, avoid thunderstorms by __NM
10NM
When flying below freezing level, avoid thunderstorms by __NM
5NM
When flying below freezing level, avoid thunderstorms by __NM
5NM
When flying near a severe thunderstorm, avoid it by __NM
20NM
Where is the most dangerous part of a storm for hail?
Right below the anvil; because pilots thinks it looks clear but it’s severe hail
When is icing most severe in regards to the development of a storm?
Generally most severe just prior to the onset of the mature stage!
When is icing most severe in regards to the development of a storm?
Generally most severe just prior to the onset of the mature stage!
What kind of clouds do you encounter when approaching a warm front?
Cirrus (Ci), Cirrostratus (Cs), Altostratus (As), Nimbostratus (Ns), Stratus (S)
C-CANS
Gas to a solid:
Deposition, latent heat of sublimation
(Release heat to environment)
Solid to a gas:
Sublimation, latent heat of sublimation
(Absorbed latent heat)
Gas to a liquid:
Condensation, latent heat of vaporization
(Release heat to environment)
Liquid to a gas:
Evaporation, latent heat of vaporization
(Absorbed latent heat)
Liquid to a solid:
Freezing, latent heat of fusion
(Release heat to environment)
Solid to a liquid:
Melting, latent heat of fusion
(Absorbed latent heat)
Why is there turbulence beneath a Virga?
Rising water Vapor and descending cooler air as a product of latent heat (evaporation, latent heat of vaporization)
How does diurnal effect change surface wind speeds?
SURFACE winds
HORIZONTAL movement of air; advection. Diurnal effect means when ground is warm it heats up atmosphere and water is cool it cools the atmosphere
So, in a TAF you migh tsee the sinds make a 180 degree swap.
Land breeze = night time, blows out to sea
WARM AIR OVER SEA
Sea breeze = day time, blows in land
WARM AIR OVER LAND
Adiabatic implies ___ movement of air
Vertical!
What are the lapse rates?
Environmental
Dry = 3
Saturated = 1.5
Average = 1.98
When the tropopause is higher than standard, is its temperature warmer or colder than normal?
Colder.
If the tropopause is lower than standard, the temperature is warmer than normal
As latitude increases, temperature increases!
Latitude starts at 0 at equator
How is altimeter setting corrected?
Station pressure + correction = altimeter setting
(based on standard lapse rate & ICAO temperature)
Leaving a plane parked at night. You left the same altimeter setting in, and you arrive in the morning where the altimeter did not change, but the temperature dropped. Will it read higher or lower?
Will read the same because on the ground altimeter is corrected for temperature ONLY ON GROUND!!
How is mean sea level pressure corrected?
Station pressure corrected for standard lapse rate and 12hr average temperature = MSLP
(based on standard lapse rate & average temperature over last 12 hours!) Do not get confused with altimeter setting.
Does MSLP change when it becomes warmer than standard but station pressure remains the same?
MSLP will decrease!
Warmer air becomes less dense (less heavy), spreads apart. MSLP, same as if you had a low pressure. Easiest way to think about this; vise versa if it was colder
do not forget about 12hrs average temperature!
What are isobars based on (calculated from)?
Mean sea level pressure!
1000 mB has to be there!!! That is how you will find values on isobar charts, based on this
What causes highs and lows to form?
Divergence/convergence in earths higher atmosphere.
What is pressure gradient force?
PGF is the force created due to the change in pressure over distance
distance between isobars essentially
Where is coriolis force the strongest in earth?
Stronger to the poles & when wind speed if faster
least strong at equator, ranges from zero
Which way does the coriolis deflect the wind?
In northern hemisphere = to the right
In southern hemisphere = the the left
What is thermal wind component (gradient)?
How rapidly the temperature changes the more flow of air we have from hot to cold. Also found horizontally!
Winds are slowed by ___ before accelerating away downstream of the trough
Centrifugal forces
Trough = low pressure
Low pressure = centrifugal forces slow wind, vs a high pressure would result in a higher centrifugal force
if the air mass is moist and stable with mechanical turbulence present in lower levels, what type of clouds can you expect to be present?
Stratus and stratocumulus
What is an air mass?
Body of air 1000nm or more across with uniform moisture and temperature created by source region
Canada is affected by ___ air masses. What are they?
4 air masses 3 in summer
Winter:
- Continental Arctic (cA)
- Maritime Arctic (mA)
- Maritime Polar (mP)
- Maritime Tropical (mT)
Summer:
- Maritime Arctic (mA)
- Maritime Polar (mP)
- Maritime Tropical (mT)
Continental Arctic becomes Maritime Arctic because in summer time, the cold air that advances over frozen lakes are thawed, so they are just moist, not dry, meaning not “Continental”, and now “Tropical”
Significance to air mass names:
Maritime = moist
Continental = dry
Arctic = cold
Polar = cool
Tropical = warm
Fronts are named after the:
Cold air mass
CA + MA = Arctic front
MA + MP = Maritime front
MP + MT = Polar front
What are the fronts in our air masses?
- Arctic front (Continental Arctic front)
- Maritime front (Maritime Arctic front)
- Polar front (Maritime Polar front)
named after the cold air mass
Which 2 fronts affect Canada in the summer?
Maritime Arctic front
Maritime Polar front
Continental arctic does not exist! Just like the air masses
Factors affecting weather severity at a warm front:
- Degree of overrunning (of the cold air mass)
- Moisture of the warm air mass
- Stability of the warm air mass
Remember, a cold front is TOTALLY based on warm air mass conditions. A warm front is dependant on the degree of overruning, then moisture and stability
Fontal passage (both warm and cold fronts!) over station given METARs:
Winds veer and increase, temperature drops, pressure increases
Do NOT base your answer solely on temperature.
Temperature may not begin to decrease for 2 to 3 hours after frontal passage
Surface winds tend to remain strong after cold front passage due to incoming high pressure in behind the frontal wave
When grossing through a warm front hen a cold front, which way shall you adjust your heading to maintain track?
To the right!!! In all scenarios
Cold front with steepening frontal surface:
Upper cold front
A cold front with a steepening frontal surface is approaching your location; frontal passage has already occurred. Has WX already passed, occurring now or yet to arrive?
YET TO ARRIVE.
Steepening frontal surface is where the front ‘scoops’ up a lot sharper than at the lower levels of the front.
What would happen to your OAT as you fly through a TROWAL?
Increase then drop again once you get to cold side
How can you tell in which direction a ‘mature frontal wave’ will move?
It will move parallel to the isobars in the warm sector!
Air between the small portion of the cold and warm front will show its isobars and indicate fairly straight lines within (with strength). The entire wave will move wherever those isobars are blowing.
Remember wind blows parallel to isobars
Mature frontal wave just means the cold-warm front around a low pressure combo.
What is required to form fog?
- High relative humidity
- Condensation nuclei
- A process that will cause condensation
What are the 6 types of fog?
- Radiation fog
- Advection fog
- Steam fog
- Frontal fog
- Upslope fog
- Ice fog
know the different process that cause each fog type
All have moisture and condensation nuclei!
Radiation fog:
- Clear night (allows for cooling of ground; if clouds present, it ‘insulates’ the temperature to the ground)
Think of the morning in a valley, the temps are low at the surface and temps are high above (inversion), it causes radiation fog
Radiation fog found in low-lying areas (YHZ)
Advection fog:
Horizontal flow = advection fog = warm over cold
Warm, moist air moves over cold ground, horizontal. Cools from below, causes saturation, advection fog is formed.
Exam question: Maritime Tropical air moves northward towards Labrador Current. This can give rise to what? Advection fog.
Labrador current is very cold water from around Baffin Island. Condensation nuclei in this case would be the salt from the water
In early spring when fog forms in the vicinity of Toronto, the air mass that is most likely responsible is:
Maritime tropical. Great Lakes are freezing cold and warm air moves horizontally over them
Steam fog/sea smoke:
Really cold dry air and warm water below, moisture off warm water and saturates immediately into fog.
Only a problem if wind blows this fog over land or your airport
Arctic sea smoke/ice fog:
Really cold dry air with warmer water below and sublimates directly into ice crystals. DEPOSITION
Only a problem if wind blows this fog over land or your airport
Under what conditions will fog form off the west coast of Canada in Pacific but not over land?
Could be steam fog/arctic sea smoke, but offshore flow is keeping the fog away from land!
Pacific is relatively warm, so you would need cold and dry air with an offshore breeze
Upslope fog:
Essentially air moving up a mountain into the sky up to the point of saturation fog stays on the same side of the mountain
Exam question:
Air flowing off Pacific over Rocky Mountains can lead to what type of fog? Upslope fog
Could be when ambient reduces to dew point! Only occurrence of this
Frontal fog:
“Precipitation fog”
Rain falls from clouds into colder air below
Evaporation of droplets leads to saturation giving rise to low lying clouds and fog
Passing overhead of an airport with a thin layer of fog. What can you anticipate as you turn onto final approach to the runway?
Decreased visibility (slant range) if looking into sun
From above you can see airport but at an angle you can’t see it as well, more layers of fog horizontally. Pretty basic
Shallow fog over touchdown zone, what is true of the RVR?
Prevailing visibility will be better than RVR
Prevailing visibility comes form tower somewhere else at airport, which may be higher up than the fog layer. So the reported visibility will be greater than the RVR; just a caution to pilots.
Anabatic/Kanabatic winds:
Up a mountain in day (Anabatic)
Down a mountain in night (Kanabatic)
Called mountian breeze
An airport is located close to a coast line at the mouth of a mountain valley can experience strong winds especially under conditions of a cold stable air mass. What is the name of that wind?
Funnel mouth
Can also form on long downward sloping glaciers in the north as the cold dry dense air accelerates down the slope
Low level nocturnal jet streams:
700 - 2000 AGL up to 45kts
1.Over flat regions
2. Summer months most prevalent
3. Southwest winds
4. Low temperature inversion must be present
5. Strongest winds occur 2-3hrs after midnight
6. Dissipate after sunrise
not to be confused with a LL frontal jet stream. Nocturnal jet stream is associated as lower level and based on mountains and prairies for strength, also a clear night with an inversion
Frontal jet streams:
500 - 5000 AGL up to 100kts
- Parallel to cold front of mature low pressure system (between cold/warm region)
- Higher altitude range
- Higher speed range
- Most critical 1-3hrs prior to cold front passage!
- AFFECTS AIRCRAFT THE WORST WHEN LANDING/TAKING OFF
Not to be confused with LL nocturnal jet stream. Frontal jet stream associated with a low pressure system and jets parallel to cold front
Low level jet streams are not included on a GFA if they are above _____ft ASL, except as required over _____
LLJs not included if above 6,000ft ASL, unless as required over a higher terrain; mountains.
Height of LLJ not indicated
What are processes involved that produce larger sized rain droplets?
- Condensation
- Coalescence
- Bergeron Process
- Aggregation
- Riming
What is coalescence?
Where larger water droplets collide into smaller water droplets and then join to become even larger water droplets
A coalition is a group of people formed together
0 degrees is a ______.
Melting temperature, NOT a freezing temperature.
Water freezes at -40! You need ice nuclei in water for ice to form off of. Ice nuclei is contamination, just like condensation nuclei
What causes water droplets to freeze before even getting below -40 degrees (freezing temperature of water)?
Lerger supercooled water droplets will tend to freeze sooner (approx. -10 degrees) due to the number of impurities contiained in LARGER droplets
You are flying through cloud in flight picking up light icing and you start to see snow flakes. Would you expect the icing to get better or worse?
Its a good sign! Bergeron Process causes all water droplets to 100% freeze and cannot accumulate on your aircraft.
What happens to airframe icing once ice crystals appear within a cloud layer?
Icing decreases!! Water droplets are completely frozen and do not accumulate on aircraft.
What is riming?
Snow pellets, SC water droplets have a shell of ice around it, and if it falls to the ground it is referred to as a snow pellet
Aggregation is?
When snowflakes bang together becoming entwined and become larger
In a layered cloud, at what temperature will icing be most severe?
0 to -15 degrees, icing sits towards the tops of clouds
(icing increases with height)
(if temperatures are considerably colder, icing will decrease with height)
Icing occurs in the horizontal plane, so its a good idea to request an altitude change
In a cumulus type cloud, at what temperature will icing be most severe?
0 to -10 degrees IN LOWER PART OF CLOUD
Clear icing associated
In a convective type cloud, at what temperature will icing be most severe?
0 to -25 degrees, largest range, most dangerous. Larger supercooled water droplets in updafts and downdrafts, tends to be most severe in lower levels
-25 to -40 will generally be light icing but risk if heavy icing is still possible. Below -40 degrees, expect light RIME (small SCWD)
At what point in a convective cloud will icing be at its worst?
Just prior to the mature stage; droplets will achieve maximum values in size and quantity
Once mature stage is reached, water droplets fall out of sky through rain
What airspeed foes an airplane have to achieve so that aerodynamic heating will prevent airframe icing?
500kts or greater
AERODYNAMIC HEATING IS NOT EFFICENT AT REMOVING ALREADY FORMED ICE, IT JUST PREVENTS MORE FROM ACCUMILATING
When will rime ice form?
- Water droplet size
- Catch rate
- Temperature
Small supercooled water droplets
Low catch rate
SKIN temperatures -10 to -15
When will clear ice form?
- Water droplet size
- Catch rate
- Temperature
Large supercooled water droplets
High catch rate
0 to -10 degrees
Approaching a winter warm font from the cold side. What is the order of precipetation?
Snow
Ice pellets
freezing rain
rain
A METAR is reporting ice pellets. Where is the freezing rain located?
ABOVE
What happens to pressure level spacing when it is warmer than standard?
It increases! If colder, there’s less difference & you’ll be closer to other aircraft
On a CDA non-precision approach, how will cold weather affect it?
Angle of descent is shallower! Due to altimeter error over FAF and MDA/DA
Rotor clouds are found:
Downwind from mountain and bases extend below the mountain peak
Lens clouds are found:
On the upwind portion of the wave crest
IMMEDIATELY BELOW WAVE CREST
How does AWOS define rotor/lenticular clouds?
Rotor = below wave crest
Lenticular = At wave crest
WV = MOUNTAIN WAVE on GFA
At what speed is a jet stream with mentioning in any weather prognostic?
60kts!
Important over every weather prog chart!
Except the last one; the upper air anal states 80kts or more
What main component is responsible for strong wind speeds in a jet stream? Where would you find these?
Temperature contrasts, at fronts
Strong HORIZONTAL temperature gradients
Polar front and arctic front
What weather front produces the strongest jetstream?
POLAR FRONT which is between mP and mT; southernmost boundary of air masses, where largest temperature gradients occur. REMEMBER 60KTS, as below 60kts there will be no mention of a jet stream, like the other fronts would be less than 60
Strong HORIZONTAL temperature gradients will produce strong jet streams. Remember higher tropopause has a lower temperature
Where does CAT occur regarding the 2 air masses that meet to form a jet stream?
CAT occurs on cold side between the 2 air masses
Jet streams above ___kts at core will have significant turbulence about:
110kts at core
- Sloping tropopause above core
- In jet stream front below core
- On low-pressure side of core
in dark blue area
CAT is also related to vertical shear. Turbulence is likely when the shear is _____
Greater than 5kts per 1000ft
EXAM QUESTION: Given an OFP and upper winds, where on your flight plan will you encounter shear?
Between 2 waypoints you’ll be given the planned FL (at each point) and FLs with wind. Find where between FLs the wind speed is >5kts per 1000ft. Be aware the FDs given may be spaced at 2000ft, so make sure to divide by 2 to get the desired altitude to see the change in speed
Curving jet streams are more apt to have ____
Turbulent edges (vs. straight ones), especially ones that curve around a deep pressure trough
In the northern hemisphere, which way should you turn to avoid areas of CAT?
South, you will be turning into warm air mass
Remember that you will be moving away from the ‘dark blue’ area on Q117 if you go south. CAT occurs on the COLD side so get to the warm (South) side!
What temperature is lightning most probable to strike?
-5 to +5 degrees
How far out are the effects of a downburst?
10NM from storm centre
Difference between microburst and macroburst?
Microburst:
- 2.2NM or less (test could give you in km)
- Up to 5 minutes
Macroburst:
- 5NM or more (test could give you in km)
- Between 5 to 20 minutes
How fast can a downdraft reach?
-6,000ft/min (exceeds climb capabilities of most airplanes)
What is a dry air microburst?
A virga is a sign that a dry air microburst is occurring
Evaporational cooling causes the air to accelerate downwards. Signs on the ground is if you see a ring of dust; expect strong wind shears! (Vortex rings)
Rain falls down into hot/warm air and evaporates (absorbs latent heat). Virga. But water vapor will rise back into the air (because its warming), but now we are cooling the air back down around it, and the air falls back down; i.e accelerating the downburst.
What cloud of a thunderstorm does a tornado usually manifest?
The wall cloud
Relative humidity definition:
Water vapour present expressed as a percentage of the amount needed for saturation at the same temperature
How does drizzle form?
Collision of thin water droplets with each other in Stratus (mid to high level) clouds
Drizzle are just barely bigger than cloud water droplets; they barely big enough to fall to earth and they “Drift” down to earth and do not form puddles on ground
Moist adiabatic lapse rate is ___ than dry because of ___
Lower; Latent heat from vaporization during the condensation process
What lifting process can cause the formation of TCUs at the centre of a low pressure?
Convergence
Windshear/CAT will me worse in ____ of mountain ranges
Above and to the lee!
If CAT is present when you are flying in an area of shear and a sharp pressure trough, you should:
If turbulence is encountered with an abrupt wind-shift associated with a sharp pressure trough, a course should be established to cross the trough rather than to fly parallel to it. A change in flight level is not as likely to reduce turbulence.
JUST GO THROUGH IT, DO NOT TRY TO CLIMB
Determine the wind speed and its approximate direction over water under the following conditions:
- Pressure gradient: constant
- Surface wind speed over land: 35 knots
- Angle between the surface wind over land and isobars: 35°
45kts and 25 degrees!
The stronger the surface friction, the higher the deviation angle of the air compared to the isobars and the stronger its deceleration. This angle is lower over water than over land, especially if the land is rough. Over land, deviation can go up to 40°, whereas over water it rarely goes over 10°
So, over water, less surface friction = less wind direction deviation and HIGHER sustained winds. Over land you’ll get surface friction which deviates and slows the windspeed down; over water it will be more closer to what the isobars are showing
A sudden increase of windspeed over a long period of time is called:
A squall
A sudden increase of windspeed over a short period of time is called:
A gust
In winter, a pilot encounters freezing rain when flying through a warm front. The pilot should:
CLIMB to warmer air.
Climb up so you encounter snow at higher altitude
In a thunderstorm, thunder and lightning occur in the ___ stage.
Mature stage
___ fog appears when dew point increases to ambient temperature
STEAM fog
Cold air moves over warm water surface. Water evaporation (latent heat absorbed, colder air now) saturates cold air. Forms condensation and creates fog. Any time you see the “dewpoint increases to ambient” think steam fog & (new) FRONTAL FOG
ON EXAM THERE IS AN OPTION TO DECREASE OAT TO DEW POINT; IT DOESN’T WORK LIKE THAT
OCCURS IN FALL OVER LAKES AND RIVERS (weather starts to get cooler outside)
OCCURS OVER A BODY OF WATER IN ARCTIC IN PATCHES OF ICE!!!
What is the intertropical convergence zone (ITCZ)?
Where solar radiation is at its strongest! I.e. equator
Why does the ITCZ move south in the winter months?
Because earth tilts away from sun and ITCZ moves southward
Temperature at tropopause is ____ at the poles
Colder
Height of tropopause is higher over equator because _____.
Density is LESS! Overall air density is less; more buoyant
Height of tropopause will be higher in a _____ air mass and when MSL pressure is ____
Warm air mass, MSL pressure is high!
Lower atmosphere is warmed by:
Short wave (UV) and long wave (IF) radiation
Coriolis force is stronger at poles or equator?
Stronger at poles
What is responsible for turbulence in lower 3000ft of troposphere?
Orographic lift
Expansional cooling, condensation, formation of cloud: What phenomenon is this?
Overrunning
Subsiding air even if initially saturated, will:
Warm at dry adiabatic lapse rate
Stability of a warm dry air mass depends on the relationship between:
Dry and environmental lapse rate
Vertical distance between any two pressure levels is less in ____ air and more in ____ air
Les in cold air and more in warm air
What does a summer with flat terrain imply? (keyword)
INVERSION!
Lenticular clouds are found:
Below wave crest! So on the ‘up” part of the wave crest, but below where the wind is
406 ELT are:
- Satellite-based
- ELT sends unique signal to satellites in orbit
- Improves accuracy to within approximately 5km
How often are Upper Air Analysis charts issued?
Twice a day at 0000Z and 1200Z, 3 hours after data is recorded
As a cold front approaches a stable warm air mass, the cold front will:
Be steeper and advance more quickly; less turbulent resistance
What will happen to your temperature as you fly through a jet stream?
Decrease
jet is always on the cold side!
Fog that forms in the cold air section of a warm front because of:
**Cold* air becomes saturated from rain falling from warm air
Flying through a jet stream and temperature decreases, what shall you do?
Descend!
if temps increased, climb the aircraft to escape CAT
What causes coriolis force?
Earth’s rotation
What front rarely appears during summer months in Canada?
Continental Arctic front
What is a contour line?
Constant pressure slope of pressure surface
What weather conditions can you expect from a TROWAL?
TROWAL is usually an area of intense lift; hence it being unstable.
Expect heavy/prolonged precipitation
Heaviest snowfall amounts in winter are also associated along a TROWAL axis
you are at an airport which experiences the passage of a cold front in the early afternoon. Shortly afterwards, the clouds scatter out leaving a clear sky. During the next 12 hours, you would expect the temperature to:
increase slightly then decrease!
Counter-intuitive
It clears up behind the cold front for an hour or two (warming things up slightly) and then clouds over (so it starts to cool down)
So, not really anything to do with the cold front itself, more of the environment it leaves. Initially it will clear the sky (warm), when clouds will form (cool)
How is an occluded front formed?
When a cold front catches up to a warm front and begins to under-cut it.
Occlude - to close up or block off
What marks the onset of the mature stage of a storm?
Rain reaching the ground
DOWNDRAFTS!
What fronts are most prevalent in winter months in Canada?
Continental Arctic
Maritime Arctic
If temp increases in CAT, you should ____
If temp decreases in CAT, you should ____
If temp stays the same in CAT, you should ____
CLIMB IF TEMP INCREASES
DESCEND IF TEMP DECREASES
CLIMB OR DESCEND
Snowflakes that receive a coating of rime ice as it falls through layer of supercooled water droplets and reaches the earths surface will be reported as:
Snow pellets! Riming is associated with a “shell” and the supercooled water droplets GS
snow pellets are heavier due to the supercooled water droplet shell
You see RIME, think RIMING. Snow with ice shell sounds a lot like a snow pellet!
Drizzle that falls through a below-freezing layer and freezes before reaching earths surface is reported as:
Snow grains! Drizzle are thin/small wispy rain parts. When it goes to a below-freezing layer, it gets slightly heavier and falls to ground called SG
Dissipating part of a storm is characterized by:
DOWNDRAFTS!!! Not just rain hitting surface like from CPL; downdrafts are super dangerous!
What causes jet streams to accelerate and decelerate?
Centrifugal forces
