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Meteorology Flashcards

1
Q

Vertical divisions of the atmosphere

approximately

atmosphere contains

A

78% by volume of nitrogen , 21% of oxygen with the remaining 1% consisting of argon , neon , helium and carbon dioxide

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2
Q

Vertical divisions of the atmosphere

force

amount of

A

exerted on a given area is called atmospheric pressure

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3
Q

Vertical divisions of the atmosphere

of the mass

3/4

A

of air is contained in the levels below 8km

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4
Q

Vertical divisions of the atmosphere

This reigon is known as the

A

tropo-sphere

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5
Q

Vertical divisions of the atmosphere

Overlying this is the

A

stratosphere

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6
Q

Vertical divisions of the atmosphere

Only reigons of the atmopshere

A

in which aircraft can operate unless they are powered by rockets

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7
Q

Vertical divisions of the atmosphere

Usually the temprature of air decreases with altitude within the

A

troposphere at a rate of approximately

2 degree C / 1000 feet

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8
Q

Troposphere

At the upper boundary of the troposphere the

temprature

A

remains constant with an increase in altitude

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9
Q

Troposphere

When this occurs temp is said to be

A

isothermal

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10
Q

Troposphere

Level at which this occurs at is known as the

A

tropopause

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11
Q

Troposphere

Temp in tropopause usually in the reigon of

A

-57 deg C

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12
Q

Troposphere

Troposphere varies in height

Over the equator

A

height of approximately 18 km (60 , 000 feet)

temp may be low as -80

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13
Q

Troposphere

Troposphere varies in height

Over the poles

A

height of approximately 8km
(26 000 feet)

Temp around -50 deg C

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14
Q

Stratosphere

extends vertically beyond the the tropopause to an altitude of approx

A

50 km above the earths surface

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15
Q

Stratosphere

Layer is generally characterised by

A

clear skies since very little water vapour is present

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16
Q

Stratosphere

In the lower levels of the stratosphere

temprature

A

is isothermal

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17
Q

Stratosphere

Within upper levels of the stratosphere

temprature

A

may increase significantly with an increase in altitude

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18
Q

Atmospheric stability

Weather we experience everyday largely result of

A

vertical motion within the atmosphere

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19
Q

Atmospheric stability

Motion may be either

visible or invisible

A

visible to the eye (as cloud forms)

invisible ( when dry air descends)

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20
Q

Atmospheric stability

Stable atmosphere

A

Parcel of stable rising air descends again

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21
Q

Atmospheric stability

Unstable atmosphere

A

Parcel of unstable rising air continues to rise

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22
Q

Neutrally stable atmosphere

A

Parcel of neutrally stable air rises and remains at a new position

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23
Q

Humidity

Humidity used to describe

quantity

A

of water vapour present in a particular volume or parcel of the atmosphere

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24
Q

Relative humidity

Refers to the ratio of the mass of

A

water vapour present per unit volume of air to that required to saturate the air

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25
Q

Relative humidity

Term expressed as a

A

percentage

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26
Q

Relative humidity

RH may change if there is a change in

temp

A

of the parcel of air without a change in the water vapour content

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27
Q

Relative humidity

As parcel of air cools ability to hold

A

water vapour decreases and so relative humidity increases

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28
Q

Relative humidity

RH of air increases ability to

A

accept more water vapour decreases

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29
Q

Relative humidity

Air can no longer

accept

A

any more water vapour. It is said to be saturated or its relative humidity has reached 100%

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30
Q

Dew point

Temprature to which a parcel of air

saturated

constant

A

must be cooled at a constant pressure for it to become saturated

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31
Q

Adiabatic process

A process which takes place where

transfer

no

A

no heat transfer takes place between the environment and a parcel of air.

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32
Q

The Environmental lapse rate

Rate at which temp of

atmosphere

A

atmosphere changes with altitude

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33
Q

The Environmental lapse rate

If temp of atmosphere was to decrease with altitude

ELR positive or negative

A

ELR would be positive

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34
Q

The Environmental lapse rate

If temp was to increase with altitude

ELR positive or negative

A

ELR would be negative

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35
Q

Inversions

A temp inversion is a

layer

A

narrow layer of the atmosphere where temp **increases **with height

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36
Q

Inversions

Inversions typically prohibit

extent

A

the vertical extent of clouds

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37
Q

Inversions

When inversion layer near to surface of earth

visbility

A

surface visiblity may be reduced due to smoke haze or fog trapped beneath or within this layer.

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38
Q

Inversions

Because vertical movement of

A

air cannot take place , thermals do not occur and flight conditions are smooth

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39
Q

Dry adiabatic lapse rate

A small parcel of rising air usually cools

differently

A

adiabatically at a value different to that of the ELR.

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40
Q

Dry adiabatic lapse rate

atmosphere is equivalent to

If parcel of air is unsaturated

A

3 deg C per 1000 feet

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41
Q

DALR

A

3 deg / 1000 feet

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42
Q

Saturated adiabatic Lapse Rate

When parcel of air reaches the temp at which RH reaches

A

100% the air is said to be saturated

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43
Q

Saturated adiabatic Lapse Rate

Temprature at which this occurs

and the height

A

is dew point

saturation or condensation level

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44
Q

Saturated adiabatic Lapse Rate

If parcel of air continues to rise above this height

A

water vapour begins condensing into droplets

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45
Q

As it does condense into droplets

gives up

A

it gives up its latent heat of vaporisation into the parcel of air warming it

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46
Q

Saturated adiabatic Lapse Rate

Rising parcel of air cools at a rate of

A

3 deg C / 1000 feet

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47
Q

Saturated adiabatic Lapse Rate

But is warmed due to

A

latent heating at rate of 1.5 deg C / 1000 feet

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48
Q

Saturated adiabatic Lapse Rate

The nett result is the rising parcel of air cools at

A

1.5 deg C / 1000 feet

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49
Q

Saturated adiabatic Lapse Rate

SALR =

A

1.5 deg C / 1000 feet

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50
Q

Unsaturated air

The atmosphere is stable if the

ELR

A

ELR is less than the DALR

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51
Q

Unsaturated air

In an unstable atmosphere the

ELR

A

ELR is greater than the DALR

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52
Q

Unsaturated air

when temp of parcel =

temp of

A

temp of enviroment the parcel will stop rising

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53
Q

Cloud base , Tops and Freezing level

base of cloud

can be what

A

can be calculated if the dew point temprature is known

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54
Q

Cloud base , Tops and Freezing level

Initially , the rising parcel of air

what does it do

A

cools at the dry adiabatic lapse rate.

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55
Q

Cloud base , Tops and Freezing level

Once the dew point temp has been reached the parcel of air then

A

cools as it rises at the saturated adiabatic lapse rate until temp of parcel of air at particular altitude is the same to the enviroment at that height.

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56
Q

Cloud base , Tops and Freezing level

The freezing level of the cloud can be determined by calculating

height

A

the height within the cloud where the temp is 0 deg C

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57
Q

Cloud formation

Whenever a parcel of air containing

what

A

water vapour rises and cools , there is a possibility of cloud formation.

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58
Q

Cloud formation

4 methods of cloud formation are

A
  1. convection
  2. forced ascent
  3. fronts
  4. wide spread ascent
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59
Q

Convection

A convective cloud forms when a parcel of air

A

ascends as a result of being heated by the earth’s surface

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60
Q

Convection

Convection produces what type of clouds

A

a cumuliform type of cloud , either cumulus or cumulonimbus

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61
Q

Forced ascent: Mechanical Turbulence

Usually experienced within region of atmosphere known as the

A

friction layer

62
Q

Forced ascent: Mechanical Turbulence

Caused by air moving over

A

irregular surface of the earth

63
Q

Forced ascent: Mechanical Turbulence

This layer typically extends up to

A

2000 - 3000 feet above the earth’s surface

64
Q

Forced ascent: Mechanical Turbulence

Air is thoroughly mixed causing

temp

A

temp and humidity to be fairly uniform

65
Q

Forced ascent: Mechanical Turbulence

This mixing may lead to the formation of what types of clouds

A

formation of stratus and strato-cumulus cloud

66
Q

Forced ascent: Mechanical Turbulence

In some cases moderate

to

A

to severe low level turbulence

67
Q

Forced ascent: Orographic Uplift

Clouds may form as a consequence of air being forced to rise

over what

A

over obstructions like mountains or hills

68
Q

Forced ascent: Orographic Uplift

What cloud will form if moist air is forced to rise in a stable atmosphere

A

Stratus cloud

69
Q

Forced ascent: Orographic Uplift

Stratus cloud characterised by a

A

flat base and relatively little vertical extent.

70
Q

Forced ascent: Orographic Uplift

After air has been forced to flow up and over the mountain it will flow in a

A

wave pattern on the leeward side before settling back into a steady flow

71
Q

Forced ascent: Orographic Uplift

This wave pattern is known as a

A

standing wave or mountain wave

72
Q

Forced ascent: Orographic Uplift

If the air is moist and stable what clouds will form in the crests of the wave

A

lenticular (or lens shaped) clouds

73
Q

Forced ascent: Frontal lifting

Clouds also form when there is an interaction between

two

A

two dissimilar air masses

74
Q

Forced ascent: Frontal lifting

As cold air (which is more dense) encounters warm air

A

the cold air moves under the warm air in the form of the wedge

75
Q

Forced ascent: Frontal lifting

The boundary between the two air masses is called

A

a cold front

76
Q

Widespread Ascent and frontal lifting

Widespread ascent occurs due to the

flowing

A

flowing together (convergence of surface air)

77
Q

Widespread Ascent and frontal lifting

Can occur in high or low pressure areas

A

Can occur in low pressure areas

78
Q

Widespread Ascent and frontal lifting

Occurs along a warm front , where warm air

gradually

A

gradually rises up and over colder air

79
Q

Widespread Ascent and frontal lifting

Also along a cold front where air is

forced

A

forced violently upwards

80
Q

LOW

Low pressure systems referred to as

A

cyclones or depressions

81
Q

LOW

Circulation around a low in the southern hemi is in the

A

clockwise direction

82
Q

LOW

When warm air at the surface warms due to

A

surface heating it becomes less dense and rises

83
Q

LOW

When the air rises the air at the

A

surface flows in to fill the space left by the rising air

84
Q

LOW

The rising air carries

A

water vapour from the surface and as it rises, it cools and expands.

85
Q

LOW

Once the rising column of air reaches the dew point temp

A

the water vapour in the column condenses to form clouds.

86
Q

LOW

Weather associated with low pressure systems is

A

often unstable and may be associated with rain and wind.

87
Q

HIGH

High pressure systems are also known as

A

anti cyclones

88
Q

HIGH

In southern hemi wind circulation is

A

anticlockwise

89
Q

HIGH

A high pressure system starts with

cold air

A

cold air at high altitude which starts sinking

90
Q

HIGH

As the air sinks the pressure at the surface

A

rises just as pressure increases the further down in the ocean you go

91
Q

HIGH

When the sinking air reaches the surface it

spreads

A

spreads out in all directions to make way for more air from above

92
Q

HIGH

Weather associated with a HIGH is

A

stable

93
Q

HIGH

Air in a high pressure area compresses and

A

warms as it descends

94
Q

HIGH

This warming inhibits the formation of

A

clouds meaning the sky is normally sunny in high pressure areas. But haze and fog still might form.

95
Q
A
96
Q

Ridge

Defined as an elongated

area

A

area of high pressure extending along an axis often callled the ridge axis

97
Q

Ridge

The pressure is always lower on

either

A

either side of the ridge axis

98
Q

Trough

An area of elongated

pressure

A

low pressure extending along an axis. This is often called the trough axis.

99
Q

Trough

Pressure always

higher or lower

A

higher on either side of the trough axis.

100
Q

Trough

Trough associated with what flying conditions

A

bad

101
Q

Col

region between two

highs or lows

A

highs

102
Q

Col

area of

what weather

A

‘nil weather’ and flying conditions are good

103
Q

Sea Breeze

During warmer months of the year

at what times?

an onshore or offshore wind is experienced ?

A

an on-shore wind is often experienced n the late morning or early afternoon

104
Q

Sea Breeze

What is it caused by

A

Caused by differential heating of the land and sea.

105
Q

Sea Breeze

During the day , the land (and air close to it)

what happens to it

A

warms rapidly as it absorbs solar radiation.

106
Q

Sea Breeze

During the same period of time temp of

ocean

A

the ocean only rises slightly.

107
Q

Sea Breeze

Water requires much more

to raise

A

heat to raise its temperature than does the earth.

108
Q

Sea Breeze

As the heated air over the land becomes

dense

A

less dense and rises , it is replaced by cooler and more dense air from over the ocean

109
Q

Land Breeze

Associated with what areas and at what time

A
  • Associated with coastal areas an occurs at night
110
Q

Land Breeze

During evening land

land cools faster or slower than ocean

A

cools at a faster rate than the ocean.

111
Q

Land Breeze

As a result the temp of the land will be signifcantly

lower or higher than that of the sea?

A

be lower than that of the sea

112
Q

Land Breeze

This causes air close to the land surface

heat or cool

A

to cool and its density and pressure to rise

113
Q

Land Breeze

Higher pressure over the land flows into

what does the less dense air do

where the lower pressure area of the

A

the lower pressure area over the sea where the less dense air now rises.

114
Q

Land Breeze

What flow is established

A

A circular flow is established

115
Q

Katabatic Winds

When do they form , do they go up or down hills or mountains

A
  • Form in the evening, come down into valleys or slopes of hills or mountains.
116
Q

Katabatic winds

What nights is it usually strongest

A

on cloudless nights when the land surface loses its heat by radiation.

117
Q

Katabatic winds

Near tops of mountains the air close to the

conduction

A

ground is cooled by conduction

which results in it becoming more dense than the surrounding air

118
Q

Katabatic winds

The colder more dense air

what does it displace

does it slide up or down the mountain

A

slides down the mountain and displaces the less dense air below it.

119
Q

Katabatic winds

Through the descent the air continues to lose

A

heat to the environment

120
Q

Strength of Katabatic winds are related to the surface over which they travel.

A

If the surface was rough and undulating, the strength would be minimal.

121
Q

Anabatic winds

When does it form , do the winds go up or down

A

Forms during the day and flows up hill slopes.

122
Q

Anabatic winds

When are they strongest

A
  • Anabatic winds are strongest on warm cloudless days.
123
Q

Anabatic winds

In these situations, the earth is able to be

solar radiation

heated or cooled

A

to be heated to a significant value by solar radiation.

124
Q

Anabatic winds

Air in contact with the surface of the slopes

becomes wamrer or colder

A

becomes warmer than adjacent air.

125
Q

Anabatic winds

It rises and is replaced

cool or hot air

by what air

A

by the cooler, more dense air.

126
Q

Foehn Winds

May form as a result of moist air being forced to rise over

A

a mountain barrier

127
Q

Foehn winds

If sufficient moisture is present during the forced ascent

A

the water will condense into cloud

128
Q

Foehn winds

Precipitation generally occurs

on which side the windward or leeward

A

on the windward side of the mountain range

129
Q

Foehn winds

Once over the mountain range , the air which is colder and more dense than its surroundings

how is it warmed

will rise or descend

A

will descend and is warmed due to adiabatic heating

130
Q

Foehn winds

When the air (Foehn wind) reaches the lower slopes of the mountain

is it dry or moist

is the wind warm or cool

A

it is usually a warm , dry wind

131
Q

Air Masses

In Australia, three major air masses influence our weather: what are they

A
  • Equatorial
    • Tropical
      -Polar
132
Q

Air Masses

Equatorial Maritime what is it

A

○ Situated in Northern Australia
○ Contains large amounts of moisture
○ Considerable amount of precipitation in wet season [November - March]

133
Q

Air Masses

Tropical what is it

A

○ Tropical Pacific
§ Moist and origins in pacific Ocean
○ Tropical Indian
§ Moist originates in Indian Ocean
○ Tropical Tasman
§ Originates south of continent, cooler and contains less moisture than Pacific or Indian
○ Tropical Continental
§ Dry and forms a result of being modified as it passes over mainland Australia for extended periods of time

134
Q

Air Masses

Polar what is it

A

○ Polar Maritime
§ Originates far south of continent and considered to be coldest of all air masses. Ice, snow and very cold winds may be associated with this air mass
○ Southern Maritime
Originates as either a Polar Maritime or Indian ocean air mass. Generally cold and moist and affects southern part of continent

135
Q

Front

What is a front: The boundary between

A

two disimilar air masses is often referred to as a front

136
Q

Cold front

A cold front starts to develop when a body of advancing

A

cold air encounters a region with warmer air.

137
Q

Cold front

As the frontal system approach, the air pressure

does it drop or increase

A

continues to drop. It reaches its lowest point as the front passes, and starts to climb again in its wake.

138
Q

Cold Front

Cold air in the frontal system is much denser than the preceding warm air. As a result

A

the leading edge of the cold front easily pushes underneath the prevailing warmer air, lifting it into the atmosphere.

139
Q

Cold front

The speed and abruptness with which the warm air is forced to ascend, allow for the

A

rapid condensation of water vapor and the formation of storm clouds.

140
Q

Cold Front

This rapid development creates ideal conditions for the creation of heavy

A

downpours and thunderstorms. It is in these storm systems that severe weather conditions such as hail, lightning, and thunder can occur.

141
Q

Cold front

Air temperatures also start to drop substantially as the

A

old front approaches, reaching its lowest point as the front passes. It remains cool as the body of cold air moves in behind the leading edge of the frontal system.

142
Q

Cold front

Following the passage of a cold front there is a

A

rise in atmospheric pressure

decrease in temprature

143
Q

Cold front

Different clouds will form with passage of cold front:

if the warm air is stable

if the warm air is unstable

A

if the warm air is stable then stratiform cloud like cirrostatus and altostratus will form

if the warm air being lifted is unstable then cumuliform clouds will develop.

Such clouds may include cumulus , cumulonimbus

144
Q

Warm front

A warm front starts to develop when a body of advancing warmer air encounters

A

a region with colder air.

145
Q

Warm front

Since warm air is less dense than the cold air, it cannot

A

displace it. Instead, the leading edge of warmer mass gradually rises over the boundary of the prevailing cool air.

146
Q

Warm front

As the air continues to rise on the back of the colder air mass, it starts to

A

ool down until the water vapor can no longer be contained in gaseous form, and condensation takes place.

147
Q

Warm front

The gentle gradient at which the air rises leads to the formation of uniform

A

stratus clouds that are responsible for producing prolonged spells of soft precipitation.

148
Q

Warm front

As the warm front passes, the atmospheric conditions are characterized by

A

warmer temperatures and a decrease in air pressure.

149
Q

Australian Seasonal Weather Patterns

Summer:

A

Highs on the great lite or bottom of Australia and lows in the middle

150
Q

Australian Seasonal Weather Patterns

Winter:

A

Lows on the great lite and highs in the middle

Aviation (3 decks)

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