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PPL/RPL > Meteorology > Flashcards

Meteorology Flashcards

1
Q

The equatorial trough is a region of low pressure caused by..?

A

Warm air rising neat the equator

The solar radiation is more intense near the equator. The surface of the earth becomes hot and the air in contact with the hot surface is heated by conduction. Hot air expands and becomes lighter so it rises causing the surface pressure to drop.

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2
Q

The layer of the atmosphere in which most convection takes place

A

The troposphere

Temperature within the troposphere decreases as height increase.rising air will continue to rise only if it remains warmer (lighter)than the environment.

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3
Q

Vertical movement within the atmosphere becomes less vigorous above the height of the tropopause because. ?

A

The environment longer gets colder with increased height.

Tropopause beginning of the isothermal layer. Above that the temperature increases with height. ( rising air can no longer remain than the environment, so it tend to rise)

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4
Q

What is the belt of high pressure that frequently appears over the Australian continent?

A

The sub-tropical Ridge

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5
Q

The equatorial trough features extensive cloud and weather because..?

A

It is a region where converging airstreams rise over warm ocean due to the intensity of solar radiation.

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6
Q

There is very little convection within the stratosphere because..?

A

The air at the top of the layer is Warmer than the air at the bottom.

Temperature in the stratosphere either remains constant or increases as height increases. Rising warm air quickly encounters air that is the same temperature and tend to rise.

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7
Q

What force does pressure gradient acts up on ?

A

At right angles to the isobars towards the lower pressure.

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8
Q

What strength do the pressure gradient depend on most?

A

The spacing of isobars

The closer the isobar spacing, greater is the rate of change of pressure as you move across them.

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9
Q

In the Coriolis effect which direction does the wind tend to flow?

A

Flow anticlockwise about a high.

To the left in the southern hemisphere.. turning left is also turning clockwise.

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10
Q

Surface wind , when compared to gradient wind flow, is found to be..?

A

Veered to the right and slower

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11
Q

Compared to the gradient wind flow, the surface wind over land will have veered or backed ?

A

Veered by 30° and slowed by two thirds.

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12
Q

The term geostrophic wind

A

The steady flow of wind along straight isobars

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13
Q

Where does anticlockwise and clockwise flow occurs?

A

Anticlockwise - high in the southern hemisphere

Clockwise - low in the southern hemisphere

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14
Q

Compared to the gradient wind, the surface wind is always deflected in what direction?

A

Across the isobars and towards the lowest pressure

Surface wind always favour of the pressure gradient.(away from high or towards low - always to the right in the southern hemisphere)

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15
Q

Backing wind

A

It is changing direction anticlockwise
Eg. Change from southerly to easterly

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16
Q

Compared to the gradient wind, the surface wind direction in the southern hemisphere is found to be .?

A

Further to the right in both highs and lows.

High pressure system the air flowing out at the surface,

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17
Q

In which conditions are well developed cumuliform clouds most likely firm?

A

Latitudinal heating of a fast moving cold moist air stream.

When the temperature at the bottom of an air mass is much warmer than at the top, strong convection is triggered. When cold moist airstream moves north in the southern hemisphere, the increasing surface temperature warms its lower layers producing cumuliform cloud.

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18
Q

Which cloud type is most likely to produce virga?

A

Thin altrostratus

Virga occurs when the water droplets or snowflakes which leave the cloud base, evaporate before reaching the ground. It observed when the droplets are small and have long way to fall. Altrostratus are weak and can support only small droplets. Small droplets falling are more likely to be evaporated before reaching the ground.

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19
Q

What weather is encountered in nimbostratus cloud?

A

Heavy continous rain or snow

Moderate showers

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20
Q

Most common way for cumulus cloud to form?

A

Rising air being cooled by expansion

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21
Q

Latitudinal heating of a cold air stream produces what weather?

A

Instability, possibly thunderstorms

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22
Q

What cloud is low ceilings and reduced visibility ?

A

Nimbostratus

Low base and continuous rain create worst conditions that a VFR pilot cope with.

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23
Q

What cloud types belong to the high étage?

A

Cirrostratus

Cirro indicates high cloud

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24
Q

What cloud type is turbulence in the surface layers of the atmosphere most likely to produce?

A

Stratocumulus

The rising air in the turbulent layer reaches its dew point temperature and cloud forms. Once formed, the cloud dissipates as the air sinks and warms.
The cloud layer is continually being formed and dissipated between the condensation level and the top of the turbulent layer.

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25
Q

What cloud type is responsible for the halo phenomena

A

Cirrostratus

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26
Q

What variation in wind and temperature normally occur with the passage of cold front?

A

The wind backs and temperature falls

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27
Q

Squall line

A

A low cloud moving rapidly in the warm air ahead of a cold front.

Associated with line of thunderstorms which form in the warm air along the front.

28
Q

What conditions are most likely to produce radiation fog?

A

Nil cloud and light wind

No cloud allows maximum heat loss during night due to terrestrial radiation. The light wind ensure that enough cold air is mixed near the surface to cause the fog to form

29
Q

During what stage of a thunderstorm would lighting be most frequent?

A

The mature stage

Static electric charge which produce the lighting becomes greatest in the turbulent air within the cloud during the mature stage.

30
Q

What is lifting of fog caused by?

A

An increase in wind strength

31
Q

What phenomena in a thunderstorm cause low level wind shear at some distance away from the cell?

A

Downdraft

32
Q

Where are tornadoes most likely to be encountered?

A

Active thunderstorms

33
Q

What area is a tropical cyclone likely to form?

A

Over pacific ocean at 15°S
Further south of the Ocean is not warm enough to provide water vapour. North is not enough Coriolis effect to cause circulation. Cyclones never form on land

34
Q

During the mature stage of a tropical cyclone what happened to the central pressure?

A

Remains constant

35
Q

When would you expect the effect of a land breeze to be strongest?

A

Just before sunrise

36
Q

What cloud type is clear ice most likely during flight above the freezing level?

A

Nimbostratus

37
Q

Where in the vicinity of mountain waves is the rotor zone located

A

The air at the crest of the wave curls under to produce rotor zone. Lenticular clouds form.

38
Q

What process is involved in the formation of hoar frost?

A

Deposition of ice directly from the water vapour mixed with the air.

39
Q

What conditions produce mountain wave activity?

A

A stable layer of air near the height of the Ridge. Stable air is required to allow wind to readily flow down the Lee side of the mountain.

40
Q

Under which conditions is the formation of clear ice on an airframe ?

A

During flight above the freezing level in nimbostratus cloud.

41
Q

During a flight what cloud type are likely to form clear ice?

A

Thick altrostratus cloud

42
Q

What synoptic situations can produce radiation fog?

A

Near the centre of a high pressure system.

43
Q

What pressure system gives rise to a subsidence inversion?

A

Anticyclone

44
Q

What conditions produce advection fog?

A

Warm air passing over a cold surface

45
Q

Name one prerequisites for the formation of a thunderstorm

A

There must be enough water vapour present to allow the development of a large cloud mass.

46
Q

What hazard is to be encountered when flying above an active squall line?

A

Severe turbulence

47
Q

What does thunderstorms occur well after a cold front has passed?

A

The surface over which the cold air is passing is increasingly warmer than the cold air mass.

48
Q

When does adoption fog form?

A

Warm air passes over a cold surface

49
Q

What weather conditions would be likely after the passage of a warm front in the southern hemisphere?

A

Nil. Stable

50
Q

One hazard that can be indicated by the presence of virga?

A

Micro brust activities

51
Q

What hazard can dust storm produce?

A

Severe visibility restrictions over a widespread area to heights above 10,000ft.

52
Q

What synoptic situation is most likely to produce a subsidence inversion?

A

A high pressure system

53
Q

Clear ice occur?

A

After leaving the freezing level on climb in nimbostratus cloud.

54
Q

Causes of slant visibility fog?

A

The runway is visible from over the top but not in the circuit area or on final.

55
Q

What synoptic situations produce a line of severe thunderstorms?

A

Convergence along a trough line.

56
Q

What conditions would be most conducive to the formation of the thunderstorms?

A

Latitudinal heating causes vigorous convection and instability.

A cold stream moving towards the equator

57
Q

What hazard is likely to occur during cumulus stage in thunderstorms?

A

Severe airframe icing
Only updrafts present

58
Q

The runway at a coastal aerodrome runs parallel to the coast. When would the crosswind component be likely to be strongest?

A

The sea breeze is strongest in the early afternoon

59
Q

What factor is the most influential as it whether rime ice or clear ice will form?

A

The size of the superposed droplets.

Small - Rime ice
Big - clear ice

60
Q

TAF YBBN 131845Z 1320/1408 18015KT 9999 RA/SHRA SCT010 SCT020 OVC100
TEMPO 1320/1402 3000 +RA BKN010
INTER 1402/1408 3000 BKN010
T10 12 16 17 Q1023 1024 1022 1020

The visibility forecast for an arrival at 2300Z

A

10km or better, with reductions to 3000m for periods of 30 mins or more but less than one hour

61
Q

TAF YKRY 061830Z 0620/0708 12005KT 9999 BKN008 OVC100
FM 062300-SHRA BKN030
T11 13 18 20 Q1023 1025 1024 1022

Rain showers are forecast?

A

From 2300 to the end of the forecast validity period.

62
Q

TAF YCAS 120045Z 1220/1308 18010KT 9000 RA BKN015 OVC100
FM 130100 SHRA BKN020
INTER 1301/1308 3000 BKN008
T10 12 16 17 Q1025 1026 1025 1022

The visibility forecast for an aircraft arriving at 0230 is?

A

3000m or 9000m or between

63
Q

The lowest cloud forecast for an arrival at 2100 is?

A

5 to 7 eights at 1500ft AGL

64
Q

AVFR aircraft plans to arrive at YCAS at 0040Z. What will apply to arrival?

AIP ENR 1.1 PARA 10.7.2.1

A

30 minutes holding fuel should be carried.

65
Q

TAF YBBN 242215Z 2400/2506 16015KT 9999 -SHRA SCT025 SCT040
T17 18 19 19 Q1020 1018 1017 1017
FM 250300Z 18020 9999 - SHRA BKN020 18/16 Q1017
RMK RF00.0/000.0 NOSIG

The cloud amount, height forecast for an aircraft arriving at YBBN at 250530 is?

A

5 to 7 eighths at 2000 ft AGL

PPL/RPL (7 decks)

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