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Cathay Pacific 2015 > Meteorology > Flashcards

Flashcards in Meteorology Deck (39):
1

Explain Jetstreams

1. Two colums of air that weigh the same, one at the pole, one at the equator.

2. The tropopause is higher at the equator, at any given altitude the air is warmer and has a higher pressure.

3. This causes a flow from the equator to the pole, which is bent by corriolous to make a westerly wind. 

4. As the greatest pressure gradiant is found at the tropopause, this is where the strongest wind will be.

5.

The Subtropical Jet is found on the poleward side of the Hadely cell

The Polar jet is found on the polar side of the ferrel cell

 

Both Jets move poleward in summer, the polar jet is more mobile then the subtropical.

2

Which Jetstream is nearest to HK?

The Sub Tropical Jet

3

ELR

-Environmental Lapse Rate

-quantified as the change in temperature per thousand feet of altitude.

-ISA ELR is 1.98°C per 1000'.

-measured by ascending a thermometer through "still" air

4

DALR

Dry Adiabatic Lapse Rate

The rate at which a rising non-saturated parcel of air cools due to expansion as it rises

Normally about 3°C per 1000'

5

SALR

Saturated Adiabatic Lapse Rate

The rate at which a rising saturated parcel of air (cloud) cools due to expansion as it rises

Normally about 1.5°C per 1000'

6

Stability

Stability is when air is forced to rise it will return to its original altitude. Big consequence is lee waves or mountain waves downwind of large obstacles to the flow.

-When the ELR is less than the SALR the air is stable.  ie ELR<1.5c/1000ft

-When the ELR is greater the DALR air is unstable ie ELR>3c/1000ft

-When the ELR is between the SALR and the DALR the air is conditionally stable.  ie ELR - 1.5c-3c/1000ft.

7

Conditional stability

When DALR is greater than the ELR, and the SALR is less that the ELR.

for example:

ELR = 2°/1000'

DALR = 3°/1000'

SALR = 1.5°/1000'

In this scenario, dry air is stable, but once saturated, becomes unstable

8

unstable atmosphere

Unstable air encourages vertical movement of air. Any parcel of air that is lifted, will continue to rise until it reaches an altitude at which it's temperature equals the temperature around it.

When the temperature in the atmosphere decreases faster than 3 degrees Celsius per thousand feet, the atmosphere's absolutely unstable.

When the ELR is greater then the DALR

http://www.boldmethod.com/learn-to-fly/weather/thunderstorm-instability/

9

ISA tropause

-56.5c @ 36,000ft

10

Temp = -56 @ FL310 what is ISA deviation?

ISA Temp = 15-(31x2) = -47°

-56 is 9 deg cooler than -47

Deviation is -9°

11

Identify Jetstream, speed of jetstream, CB's, tropopause. define XXXX and triangles

1

12

Identify Isobars, gradient meaning, low pressure system, wind direction.

1

13

Elevation 600ft and QFE is 998, what is QNH?

1018 (30'/hPa)

14

Cold Front passes, will Altimeter over read or under read?

Over read

15

Cold Front passes, will wind back or veer?

Southern Hemisphere-  Back

Northern Hemisphere - Veer

16

Warm front, will wind back or veer?

Southern Hemisphere-  Veer

Northern Hemisphere - Back

Changes are far less drastic than passage of cold front

17

Weather in a warm front? Icing? Rain? Snow? 

Snow & freezing rain.

Freezing rain can cause heavy icing as supercooled water forms ice upon contact with aircraft

18

Define CAVOK

Ceiling and Visibility OK. Used in a METAR

1. No cloud below 5000' or MSA whichever is Higher

2. Vis greater then 10Km

3. No precipetation, thunderstorms, sandstorm, duststorm, shallow fog or low drifting dust, sand or snow occurring.

19

Define Fohn wind

Warm, dry airmass moving down the lee side of a mountain as a result of humid air rising and condensing on the front side of the mountain.

Cooled at a low rate by rising at SALR, then heated at a high rate by descending at DALR.

20

Define Katabatic wind

A katabatic wind is a down-slope wind that develops as air cools in contact with cold ground and slips down the side of the hill

21

Define Anabatic wind

Anabatic wind moves up a slope as a result of conductive heating of a higher airmass. 

An example is upper cliff faces in a valley heating up with morning sun. As the local air rises, the valley air will flow upwards to replace that air.

22

Windsheer recovery technique

1. Full power

2.Wings level

2. Best rate of climb Attitude.

3. Don't change configuration until clear.

23

FG

Fog

24

BR

Mist(Brume)

25

VA

Volcanic Ash

26

GR

Hail

27

GS

Small Hail

28

SN

Snow

29

SQ

squall

30

TS

ThunderStorm

31

SG

Snow Grains

32

PRFG

Partial Fog(covering part of the Aerodrome)

33

PL

Ice Pellets

34

MIFG

Shallow Fog

35

FU

Smoke

36

BCFG

Fog patches

37

Name the three Cells

Hadley

Ferrel

Polar

38

Tropical Cyclogenisis

1. Warm water above 26.5c to depth of 50m

2. More then 500Km from the equator

3. Unstable atmosphere

4. A low level disturbance(eg ITCZ, front)

5. Less then 20Knts of windshear between ground and tropopause.

39

Hong kong typhoon season

July-Sept