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1

What types of cloud are tornadoes associated with?

Cb (mature stage of TS)

2

What time of year are tornadoes most likely to occur in North America?

Spring and early Summer as cold polar air is moving over a rapidly warming land mass

3

Diameters of a typical tornado?

tens or hundreds of metres

4

What is the lifespan of a tornado?

up to thirty minutes

5

What is the lifespan of the mature stage of thunderstorm?

up to an hour

6

What is the speed of movement of a tornado?

30mph

7

What is the name for a tornado over the sea?

A watersprout

8

What is the name for a tornado over the sea?

A watersprout

9

How do tornados move?

With the TS they are associated with

10

Typical windspeed inside a tornado?

300mph

11

What kind of pressure at the centre of a tornado?

Very low

12

What is an area typically associated with Tornados?

central plains of the USA

13

What is a funnel cloud?

A tornado type cloud that does not reach the ground.

14

What conditions trigger tornados?

Very large Cb clouds

15

What is required for very large Cb?

moist, unstable air and convective lifting

16

What is a watersprout?

similar to a tornado but takes place over the sea and does not reach the same intensity.

17

What is the name of the Cold Air Outbreak in Australia?

Southerly Buster

18

What is the name of the Cold Air Outbreak in South Africa?

South Westerlies

19

What is the name of the Cold Air Outbreak in South America

Pamperos

20

What is the name given to Cold Air Outbreaks in the NH?

Generic name of Cold Air Outbreaks!

21

When does the ITCZ pass over the equator?

Spring and Autumn equinoxes

22

When are the spring and autumn equinoxes?

March and September

23

When are the long rains?

April (the spring equinox)

24

When are the short rains?

October (the autumn equinox)

25

Where does RVR appear?

Only in METAR, it is not forecast.

26

What is the size of drizzle

Between 0.2mm and 1mm diameter

27

What are ice pellets?

precipitation which leaves the clouds as liquid (i.e. rain or drizzle) and freezes as it falls through a cold layer

28

What is the difference between ice pellets and hail?

Ice pellets are formed outside of the cloud while hail is formed inside the cloud.

29

Size of raindtrops

1mm to 5.8mm (bigger drops would break up)

30

How is hail formed?

Ice Crystal at the top of the cloud falls and gathers moisture as it does so.

31

Which cloud is Hail associated with?

Only Cb..

32

Where will the largest hailstones be found?

In Cb over continental interiors rather than over the sea because the convective and orographic triggers will be stronger over the land than sea.

33

What is the consequence of a very high freezing level (16,000ft) in equatorial regions?

Hail will melt before it reaches the ground

34

Highest level of encountering hail?

Up to 45,000ft

35

How long is the dissipating stage of a Thunderstorm?

about 2 hours typically.

36

Why is the anvil created?

Upper winds spread the ice crystals

37

Formula for PGF/Isobar spacing?

PGF = 2wVp Sin ( Lat )

38

What causes a halo around the sun or moon?

Refraction of light passing through ice crystals of cirrostratus on a warm front.

39

What is a blocking anticyclone?

A WARM quasi-stationary anticyclone that has broken away from the Azores high can disrupt the passage of the travelling lows over the North Atlantic and their associated fronts. The influence of warm highs extends into the upper troposphere these stable features will affect the sub tropical jetstream often changing its direction to flow north/south for thousands of miles. Can lead to heat waves in summer and long periods of cold weather in winter.

40

What is the temperature of a blocking anti-cyclone?

WARM!

41

What type of cloud does drizzle come from?

Stratus

42

In general is visibility greater in rainfall or drizzle?

Greater in rain as small water droplets in drizzle indicate very little lifting action but greater size raindrops indicate more lifting action and unstable air. Unstable air clears pollution vertically so visibility is better

43

Where does coalescence produce only very light rain or drizzle?

Mid-latitudes

44

What is the most northerly latitude of the ITCZ in July over Africa?

15°N

45

What is the final northerly position of the ITCZ in July in China?

30° - 35°N

46

When are there more warm occlusions?

WINTER

47

When are there more cold occlusions?

SUMMER

48

Where is the sub-tropical high pressure belt located?

Centred around 30°N / 30°S

49

Formula for Tailwind or Headwind?

Cos (angle) X Speed

50

Formula for hPA decrease with altitude?

96 * (Temperature (°K) / Pressure (hPa))

51

Formula for RH

100 - 5 (Temperature - Dew Point)

52

What are the locations of the 0° isotherm?

Poles = Ground level
Temperate Latitudes = Ground to 10,000ft
Tropics = 10,000ft - 16,000 ft

53

What are the locations of the -45° isotherm?

Arctic - 18,000ft over India
Equator - 37,000ft (Jan) - 40,000ft (July)

54

How do you convert between Kts and Km/h

1.85

55

What is the visibility for fog?

< 1000m

56

What is the visibility for mist?

1000 - 5000m

57

What are the amounts that the surface wind will differ to the free flow wind?

Over land, 30° and 50%
Over sea, 10° and 70%

58

What are the amounts that the surface wind will differ to the free flow wind?

Over land, 30° and 50%
Over sea, 10° and 70%

59

What is the cause of convergence around a low?

Surface friction

60

What is the cause of divergence around a high?

Surface friction

61

What happens to he pressure change across 100m as you go up in the atmosphere?

As you go higher up there is less change in pressure per 100m

62

What happens to he pressure change across 100m as you go up in the atmosphere?

As you go higher up there is less change in pressure per 100m

63

What wind speeds are typically quoted for radiation fog?

2 - 8 kts

64

What winds are are typically quoted for advection fog?

15 Kts

65

Formula for Density?

Density = Pressure / Temperature

66

What is the average height of the tropopause?

11km

67

What is the height of the tropopause in ISA

11 KM

68

What is the average atmosphere condition?

Conditional instability

69

What is the average atmosphere condition?

Conditional instability

70

How do we find the actual ELR?

Use of a raido sonde.

71

What does the wet bulb, dry bulb spread tell you?

About the humidity of the air
It indicates RH

72

What is the hair hygrometer used for ?

To measure humidity

73

Where does the wet bulb temperature lie?

Between the dew point and the OAT

74

What is a psychrometer?

A wet bulb and dry bulb thermometer together

75

What is the SVP over ice compared to supercooled water?

SVP less over ICE than over supercooled water at the same temperature

76

What does SVP depend on?

TEMPERATURE & SURFACE

77

What conditions do we expect to find the middle of a warm sector?

Tropical Maritime
low stratus, poor visibility, drizzle
In summer the cloud may lift and disperse but in winter the cloud base would remain low over the land

78

What conditions are likely for the formation of mist/fog?

Temperature & dew point close together

79

What is the Mediterranean climate?

Hot dry summers and cold wet winters

80

When does freezing fog exist?

if the fog droplets are supercooled.

81

Where do we find the squall line?

Ahead of a cold front

82

What is a squall line?

A line of Cb associated with an advancing active cold front

83

What is a squall?

An increase in wind strength lasting for several minutes.
Describes the increased wind produced by the gust front which precedes a TS

84

What will happen when flying into freezing or supercooled rain?

Clear ice will form

85

The pressure group in a METAR message represents what?

The QNH rounded DOWN

86

What are the relative speeds of the cold and warm fronts?

The warm front moves at about 2/3 speed of the cold front

87

What is the primary use of satellites?

to locate FRONTS in areas with few observation stations

88

What is the difference between Ns and Cb precipitation?

Ns will give continuous precipitation whereas Cb will give showers

89

What is the issue with heavy precipitation immediately ahead of an airbourne radar?

It may hide precipitation further away

90

What might we find in the warm sector in the Summery months?

Fair weather Cu

91

What does AIRMET apply to?

Low level operations only
Below FL100 or FL150 in mountainous areas

92

What is MWO?

Meteorological Watch Office

93

What is a MO

A Meteorological office

94

What does a WMO issue?

AIRMETs and SIGMETs

95

What does a MO issue?

Aerodrome forecasts and briefing documents

96

What is VOLMET?

HF and UHF
METAR & TAF

97

How is Temperature and Dew point rounded in METAR?

Rounded UP Up Up
*** Careful of rounding negative figures ***

98

How is sustained windspeed measured?

average of 10 minutes

99

Tropical Storm windspped?

> 33 Kts

100

Cyclone/Hurricane/Typhoon windspeed?

> 63 Kts

101

Relationship between cloud bases and wet/dry bulb temperatures?

the further away the wet bulb and dry bulb temperatures the higher the cloud base will be.

102

What happens to windspeed at latitude increases?

Decreases

103

Consequences of sinking air?

Dissipate cloud and trap pollution, giving poor visibility

104

Where do the trade winds blow from?

Sub Tropical Highs

105

What kind of fog might you get on either side of a warm front?

frontal fog ahead
advection fog behind

106

What is a cold air pool?

very cold upper air and warm surface air

107

What does a stormscope detect?

Electrical discharges

108

Mean temperature in polar climates?

+10

109

What is the typical latitude of the prevailing westerlies?

40° - 60°

110

Where does a microburst occur?

Under a TS

111

What causes frontal fog?

high relative humidity

112

What is a consequence of frontal fog

reduction in visibility

113

What is mixed ice?

mixture of rime ice and clear ice

114

Where is rime ice typically found?

In Ns

115

What weather is associated with a stationary high pressure region over land in the winter?

High pressure is associated with stable, sinking air. Without convective or frontal lifting there will be little or no cloud and precipitation. Any cloud formation in winter will be stratus rather than cumulus and the precipitation will be drizzle (or granular snow) rather than rain (or snow).

116

What is a stable layer at some height in the low troposphere of an older high at mid-latitudes?

A subsidence inversion

117

Which clouds can produce large water droplets?

large Cu which will contain both water droplets and ice crystals

118

What can occur over land in a col in summer?

Air Mass Thunderstorms
Lack of turbulence --> surface heating --> convective activity
Isolated, Thermally generated CBs across the area

119

What can occur in a col in winder over land?

Radiation fog

120

What are the typical col conditions?

light winds, clear skies, inversion at low level

121

What are the ATIS wind direction?

Magnetic

122

What will a sea breeze do in the NH?

Veer and increase in strength by the afternoon

123

What is the minimum Jet Stream speed?

60 kts

124

What does adiabatic mean?

heat does not enter or leave the system

125

How long does TEMPO last for ?

no more than one hour on any one occasion and the total time spent in those conditions will not add up to more than half the period

126

When will gusts be reported in a metar?

when the gust is at least 10 Kts more than the wind

127

METAR validity

only at time of observatoin

128

What does a SNOWTAM include?

information abut breaking and runway surface contamination

129

Where does breaking information occur?

in the supplementary info in ATIS & METAR

130

Where do the feathers on the wind arrow point?

towards the low pressure

131

What is a polar low?

small short lived depression that can bring frequent heavy wintery showers esp costal areas

132

Where does the sun set?

In the west in both hemispheres

133

PIREP

SPECIAL Air report

134

AIREP

Routine Air report

135

Polar ice cap is the source of which kind of air?

Arctic

136

When does a thermal low form?

Strong surface heating

137

Can a thermal low form over land?

Yes

138

Can a thermal low form over sea?

Yes

139

Can a polar low form over the land?

No

140

Can a polar low form over the sea?

Yes

141

Where does a polar low normally form?

the the arctic Maritime airmass over the North Atlantic Ocean

142

When does Rime ice form?

less that -7°C in Stratus and less that -23°C in Cumulus

143

When is there no risk of icing?

less than -45°C

144

When does hoar frost form?

when the airframe is at a temperature below 0°C and it climbs into warmer, moister air there will be direct sublimation => HOAR FROST

145

How does hoar frost form

Water vapour turns directly into water droplets on the aircraft surface: Sublimation

146

How much should you avoid a Cb by?

5000ft and 10NM normally

147

what are the air masses that are observed most frequently over Europe?

maritime Tropical and maritime Polar

148

How often does the airfield windshear alert system update?

every minute

149

Where do easterly waves form?

Close to ITCZ
5° - 20° N/S

150

What weather is associated with an easterly wave?

Severe weather;
A line of Cb and TS aligned N - S from TRAILING EASTERLY EDGE

151

What is a line of active Cb know as?

A tropical tornado

152

What percentage of easterly waves turn into TRS?

1/10

153

What is an easterly wave described as?

A ripple in the isobars which are otherwise parallel to the ITCZ

154

What kind of pressure is associated with an easterly wave?

a trough of low pressure

155

Where is the polar front jet stream speed greatest?

Between a trough and a ridge
Strongest wind will occur where you have the greatest difference in temperature and pressure

156

How much should you avoid a TS by at FL300

20NM

157

What is rain ice?

a form of very heavy clear icing encountered when aircraft are flying the rain ice triangle

158

How server is the rain ice?

Very; rain is just supercooled before hitting the aircraft, giving the worst possible clear ice with a high rate of accretion

159

What is the visibility in a heavy dust storm?

< 500m

160

What causes a sea breeze to veery?

As the breeze develops, the Coriolis force causes it to veer

161

Where are blocking anticyclones located typically?

between 50°N and 70°N

162

What wind do the isobars indicate?

the free flow wind, the surface wind will back compared to this

163

What does the advection of warm air aloft indicate?

- indicates the approach of a warm or cold occlusion
- both in NH and SH

164

When can lightning appear in a thunderstorm?

Mature stage

165

What causes lightning?

Build up of electrical potential in the cloud; upper cloud collects a positive charge while the lower cloud collects a negative charge - at a critical level this discharges as lightning.

166

What does a doppler radar do?

Record the movement of raindrops so do show turbulence in cloud

167

What can be expected around areas of convergence and divergence associated with a low?

Turbulence, Convergence results in cloud but divergence does not likely to be CAT over the divergence area

168

When can advection fog be formed?

Day OR Night

169

Visibility in blowing snow?

Whiteout, down to virtually zero

170

What are the characteristics of stable air?

Poor visibility and stratiform cloud

171

DALR close to SALR

just below tropopause where cirrus is found

172

Where is mixed ice normally found?

Ns

173

What is the vertical structure of the atmosphere?

---

174

What is the Tropopause height at different latitudes?

---

175

What are the DALR, SALR and ELR?

---

176

What is the Harmattan?

Dry, dusty, NE wind from the Sahara [ITCZ RETREAT]

177

What is the Haboob?

Sand storm associated with TS in Sudan

178

What is an example of a Foehn wind?

Chinook, [ Canadian Prairies]

179

What is the Mistral?

Northerly, from France, blowing from RHONE VALLEY, and past FRENCH ALPS. Valley wind with Katabatic enhancement (winter)

180

What favours the formation of the Sirocco?

Low pressure area in the Med.

181

What are the characteristics of the Sirocco, Ghibli and Khansin?

Dry, dusty, stabe. Blow out of the WINTER high pressure area over the Sahara in N Africa. Cause gradient wind dust storms from Algeria to Egypt. Sirocco may reach across Med to Europe bringing low stratus, advection fog and drizzle

182

What is the Bora?

Cold northerly, pure katabatic wind [ALPS]
Funnelled into river valleys
blows down mountains
comes out at Adriatic over Trieste

183

Are cold air pools more prevalent over land or sea?

Land

184

How long does a cold air pool usually last?

for the life of the system they are sitting above

185

diameter and lifespan of typical microburst ?

4km and 1.5 minutes