Meteorology Flashcards

1
Q

List four types of turbulence

A
  1. Convection turb,
  2. Orographic turb,
  3. Jetstreams/CAT,
  4. Wake turb.
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2
Q

What is an ISOTHERM?

A

A line joining places of equal temperature.

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3
Q

What causes clouds to stop rising?

A

When the surrounding air is warmer than/same temp as the cloud air.

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4
Q
Describe:
IAS
CAS/RAS
EAS
TAS
GS
A

IAS - measure of dynamic pressure.
RAS/CAS - corrected for instrument and pressure errors (IAS with a perfect gauge).
EAS - corrected for compressibility.
TAS - actual speed of aircraft through air mass. Corrected for density.
GS - TAS ± wind component for speed across ground.

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5
Q

How does a thunderstorm form?

A
  1. High moisture content,
  2. Trigger lifting
    - convection
    - turbulence
    - frontal
    - orographic
  3. Adiabatic cooling of the rising air
  4. Unstable atmosphere - once air starts to rise it continues - ELR must be greater than SLR for over 10000’.
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6
Q

Speed of sound at ISA sea level?

A

661kts.

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7
Q

As an aircraft moves from warm air to cold air, the altimeter will over or under read?

A

Over read - i.e. the aircraft will be lower than the displayed altitude.

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8
Q

How many feet of density altitude variation is there from pressure altitude per degree of temperature?

A

+120’ of altitude for every 1°c increase in temperature.

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9
Q

What is veering and backing with respect to wind?

A

Veering is wind increasing on the compass, Backing is decreasing.

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10
Q

At what speeds do cold and warm fronts move with respect to the geostrophic wind?

A

Warm fronts move slower at about 2/3 for the geostrophic wind due to the stable colder air being harder to move. A cold front moves at the same rate as the geostrophic wind.

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11
Q

What hazards are associated with CB’s?

A
  1. Torrential rain
  2. Hail
  3. Severe turb (3000fpm downdrafts / 6000fpm updrafts)
  4. Severe icing
  5. Wind-shear and microbursts
  6. Lightning
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12
Q

Calculate Mach Number

A

MN=TAS/LSS

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13
Q

What are the two cases where wind is reported in magnetic?

A

ATIS, upper winds.

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14
Q

What temps is lightning likely?

A

+10° - -10°

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15
Q

What are the different types of fog?

A
  1. Radiation fog
    - Cloudless night
    - Moist air
    - Winds 2-8 knots
  2. Advection fog
    - warm moist air flows across colder surface
    - light winds
    - e.g. valley fog
    - can be reversed - sea fog is cold air over warm water.
  3. Frontal fog
    - formed in the cold air ahead of a warm occluded front.
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16
Q

In what direction does Coriolis force act?

A

To the right in the northern hemisphere and to the left in the southern hemisphere.

17
Q

What is the adiabatic process?

A

One in which heat is neither added nor removed from a system. Any expansion or compression of gases changes the temperature (expansion cools) but the overall energy amount remains the same.

18
Q

What is the definition of CAVOK?

A

NSC below 5000’
Vis > 10km
No precip, TS, FG, SN

19
Q

How are clouds formed?

A
  1. Moisture present
  2. A lifting action:
    - convection
    - turbulence
    - frontal
    - orographic
  3. Adiabatic cooling of the rising air.
20
Q
Met decodes:
FG =
BR =
VA =
GR =
GS =
SN =
SQ =
TS =
SG =
PRFG =
PL =
MIFG =
FU =
BCFG =
A
FG = Fog
BR = Mist (Brume)
VA = Volcanic Ash
GR = Hail (GS = Small hail)
SN = Snow
SQ = Squall
TS = Thunderstorm
SG = Snow grains
PRFG = Partial Fog (covering part of aerodrome)
PL = Ice pellets
MIFG = shallow fog
FU = smoke
BCFG = fog patches
21
Q

What is a jetstream

A

A very fast upper thermal wind. Must be greater than 60kts.

Typically 1500nm long, 200nm wide and 12000’ deep.

Typically at the polar front and inter-tropical front.

22
Q

What is a thermal wind?

A

A wind generated by difference is temp. Parallel to isotherms.

23
Q

What is the ISA standard Atmosphere?

A

Temp: 15°c at sea level reducing by 1.98°c per 1000’ to 36090’ then steady -56.5°c.
Pressure: 1013.2 HPa at sea level
Density: 1225gm/m3
Speed of Sound: 340.3 m/s

24
Q

What is gradient wind?

A

Geostrophic wind plus centrifugal force from the low pressure side.

25
Q

How many feet does altitude deviate per hectapascal?

A

-30’ for every increase of 1 HPa (up to around 5000’)

26
Q

What is geostrophic wind?

A

Balanced wind between pressure gradient and Coriolis from a westerly direction.

27
Q

Describe Density Altitude

A

Altitude taking into account temp deviation from ISA IOT compare against pressure altitude for that same actual height.

More humid air also = higher DA.

28
Q

What is the dry/wet adiabatic lapse rate

A

3°/1.5° per 1000’

29
Q

How do you calculate the local speed of sound?

A

LSS=38.94 x square root of absolute temperature.

30
Q

As an aircraft moves from high pressure to low pressure the altimeter…

A

Over reads

31
Q

Describe upper winds

A

Caused by pressure differences at altitude which in turn are caused by temperature differences across different parcels of rising air. The sum of the thermal wind and geostrophic wind. (Westerly).