u13

Question 1

what is an airmass
characteristics
where is the best source region

Answer 1

airmass = body of air with same temperature and moisture in the horizontal
uniform temp/pressure = low wind variation
high P, large, flat area

Question 2

t/f: since an airmass has uniform temperature and moisture, it doesn’t experience any weather phenomena

Answer 2

false it still has weather

Question 3

weather in an airmass is determined by what 3 things

Answer 3

moisture
stability
cooling or heating processes present

Question 4

which air masses are most common in canada (from north to south) and when do they form:

Answer 4

cA = winter
mA = summer and winter
mP = summer and winter
mT = summer

Question 5

which air masses are uncommon to see in canada and why

Answer 5

cP: forms in southern canada and moves downwards to USA
cT: only few locations it can form in (arizona) and even if it tries to move upwards to canada it’s blocked by the rocky mountains

Question 6

continental arctic airmass (cA)
- characteristics
- from where
- season it appears in canada and why doesn’t it show up year round

Answer 6

cold and dry
arctic circle
moves downwards to canada in winter
not summer because 24h daylight warms the arctic

Question 7

maritime arctic airmass (mA)
- characteristics
- where does it appear in winter
- where does it appear in the summer
- what type of weather does it bring to the prairies

Answer 7

cold and moist
winter = along coast
summer = through middle of canada (from cA passing over numerous lakes in northern canada it becomes mA)
moist air from pactific passes over rockies (looses moisture) = brings dry air into prairies = clear and nice weather

Question 8

maritime polar airmass (mP)
- characteristics
- from where
- what season
- type of weather it brings

Answer 8

cool and moist
along coast summer
summer and winter
cloudy and damp weather

Question 9

maritime tropical airmass (mT)
- characteristics
- from where
- what season
- type of weather it brings

Answer 9

hot and moist
gulf of mexico
mostly summer but sometimes winter
hot humid days

Question 10

when an airmass moves, it takes on the characteristics of the surface they pass over. that airmass gets modified from _________

Answer 10

below

Question 11

what happens when cA airmass moves over a warm ocean?

Answer 11

cA gets heated from below + moisture added to it = lower levels of airmass warm and rise -> clouds = unstable

Question 12

what happens when an mT airmass moves over nunavut?

Answer 12

warm, moist airmass moves over a cold surface = inversion = lower levels cool and form fog/stratus clouds = stable

Question 13

at the tropopause, the temperature of the WARM airmass is ________ than a COLD airmass. why?

Answer 13

COLDER

warm airmass reaches higher troposphere heights = more adiabatic cooling

Question 14

cold air masses move ______ than warm airmass

Answer 14

faster

Question 15

weather at a front is determined by:
_______ of the warm airmass
_______ of the cold airmass
______ of the front

Answer 15

stability and moisture
speed
slope

Question 16

name of a front is determined by the motion of _____ air

Answer 16

cold

Question 17

at the front is a ______ pressure zone

Answer 17

low

Question 18

cold front:
- slope
- speed
- depth
- order of clouds you see as a cold front passes over your town
- how long does it last
- cold front causes the wind to ______

Answer 18

steep (1.5%)
fast
50NM
CB, NS, AS, CI
fast front = short time for bad weather
wind Veers

Question 19

warm front:
- slope
- speed
- order of clouds you see as a warm front passes over your town
- how long does it last

Answer 19

shallow (0.5%)
slow
CI, CS, AS, NS
slow moving front = weather lasts a long time

Question 20

as the cold front passes over your town, what happens to the dew point and why

Answer 20

dew point DECREASES (the temp would have to fall lower in order to be saturated)

because as the cold front passes, CB created and lots of rain falls. so the air is getting drier = decrease dew point

Question 21

as the warm front passes over your town, what happens to the dew point and why

Answer 21

dew point INCREASES (the air will be saturated at higher temperature)

because as the warm/moist front passes, water vapour is added to your air so the air will be saturated at higher temperature = increase dew point

Question 22

ice pellets and freezing rain occur ________ of a winter warm front

Answer 22

right ahead

Question 23

what is an occluded front (aka trowal)

explain the weather at a trowal (ahead and behind the trowal)

Answer 23

when a cold front catches up to a warm front and overtaking it and pushing it upwards (trough of warm air aloft)

ahead of the trowal = warm front weather
behind the trowal = cold front weather

Question 24

what is a stationary front and what’s the weather like there

which direction does wind flow in relation to the front

Answer 24

unmoving front = prolonged clouds and precipitation

wind flows parallel to front

Question 25

when flying through a stationary front directly perpendicular to it, how do i adjust my heading to account for wind

Answer 25

wind VEERS in a front (now coming from my right) so adjust heading right

Question 26

frontogenesis vs frontolysis. explain how the temperature gradient is affected during these processes, and what does that mean

Answer 26

frontogenesis = front being formed - there’s a drastic temperature difference between the two air masses and a front is about to form frontolysis = front dissipating - temperature difference between the air masses is decreasing (one of the airmasses is being modified)

Question 27

t/f. an upper front is an occlusion

Answer 27

false an upper front is when frontal weather gets pushed aloft but it’s caused by terrain (warm front forced upwards by a mountain but cold air stays on surface)

Question 28

when an upper warm front passes over a town, what changes would an observer on the ground feel? wind temperature precipitation

Answer 28

surface wind = no change surface temperature = no change precipitation = will see

Question 29

when an upper warm front passes over a town, what changes would a plane in the sky feel? wind temperature precipitation

Answer 29

winds = veer temperature = gets warmer precipitation = will see

Question 30

explain frontal fog/precipitation fog

Answer 30

a warm front makes rain = rain falls into cold air below = cold air gets saturated = fog forms

Question 31

a fast moving cold front - occurs when - weather it causes - what creates a protruding nose of cold air

Answer 31

summer intense thunderstorms surface friction creates protruding nose of cold air

Question 32

explain how an upper cold front would form

Answer 32

- mA air forced over a mountain - cA is on the other side of the mountain - cA is colder/denser than mA, so the mA sits on top = upper cold front

Question 33

explain how an upper warm front can form due to daytime heating

Answer 33

there’s a warm front on the surface daytime heating -> the temperature difference between the warm and cold airmass doesn’t exist anymore at the surface but there’s still a temp difference between the airmasses aloft, so aloft, the warm front still exists = “upper warm front”

Question 34

what is the weather like at an occluded front in winter

Answer 34

in winter, freezing rain and severe icing because rain aloft of the occluded warm air falls through freezing temperatures near the cold surface

Question 35

what are frontal waves and how are they formed what are stable vs unstable frontal waves

Answer 35

frontal wave = wave like disturbances on stationary fronts. normally wind flows parallel to stationary front, but if upper winds shift or front starts to move then a wave will form stable frontal waves don’t get worse unstable frontal waves get so big that the cold front can catch up to the warm front and form a trowal