Meteorology Flashcards
How is temperature rounded when reported?
Rounded normally
e.g. 2.2 = 2 and 2.5 = 3
When does the daily min and max temps occur?
Max = Noon + 2hrs Min = Sunrise + 30mins
Outline the ISA conditions?
Temp = 15 Celsius
Pressure = 1013.25 hPa
Density = 1.225kg/m^3
Lapse rate = 1.98 Celsius per 1000ft
When flying from high to low pressure what will happen to true altitude?
Decrease
What is QFE?
The pressure that when set will indicate HEIGHT above ground
What is QNH?
QFE changed to indicate altitude AMSL using ISA lapse rates
What is QFF?
Same as QNH but using the actual pressure lapse rate
What is an isobar?
Lines of equal pressure
What is QNE?
The height indicated at an airfield when 1013 is set on the altimeter
How does an altimeter read in air of different temperatures?
Cold air = over reads
Warm air = under reads
When is the SPS set when climbing?
When passing the transition altitude or when cleared to a FL
What is the minimum gap between the transition altitude and transition level and what is this called?
500ft and is called the transition layer
When ATIS/ATC give wind direction is this in mag or true?
Magnetic
On METARs is wind direction given in magnetic or true?
True
What direction are veer and back respectively?
Veer = clockwise Back = anti clockwise
What is buys ballots law?
Back to the wind the low pressure is on your left (in the northern hemisphere)
What is wind shear?
The rate of change of the wind in a specific area
What is required for mountain waves to form?
Stable sandwich
Wind blowing within 30 degrees of perpendicular to ridge
Min wind speed of 15 kts and increasing with height
Where can clear air turbulence be found?
Troughs, ridges, jetstreams and when isohypses diverge/converge (always above friction layer)
How can mountain waves be avoided?
Fly parallel to the ridge
Fly at elevation x2
When is thermal turbulence the greatest?
During early afternoon
What causes mechanical turbulence?
Air flowing over the earths surface and terrain obstructing the normal airflow
What is the dew point?
The temperature at which water vapour begins to condense
What is the value of the DALR?
3 Celsius per 1000ft
What is the value of the SALR?
1.8 Celsius per 1000ft
When does absolute instability occur?
When the ELR is greater than DALR
When does absolute stability occur?
When the ELR is less than the SALR
When does conditional instability occur?
When the ELR is between the DALR and SALR
What is the average ELR?
2 Celsius per 1000ft
What altitudes are classed as low, medium and high level cloud levels?
Below 6500ft = low
6500-23000ft = medium
23000ft and above = high
What altitudes can nimbostratus clouds be found?
Low and medium levels
What is virga?
Precipitation that doesn’t reach the ground
How is cloud cover defined? (octas)
0 = clear skies 1-2 = few 3-4 = scattered 5-7 = broken 8 = overcast
What the four ways CBS can be defined as?
ISOL = individual OCNL = well separated FRQ = little or no separation EMBD = embedded
Define cloud base?
The height of the lowest cloud above an airfield
Define cloud ceiling?
The lowest height of a BK base (below 20000ft) above ground or water
What visibility does fog (FG), mist (BR) and haze (HZ) give?
Fog = less than 1km Mist = 1km to 5km Haze = 1km to 5km (only formed from solid particles not water particles)
In order what precipitation causes the lowest visibility? (highest to lowest)
Hail (GR) (highest) Rain (RA) Drizzle (DZ) Sleet (RASN) Snow (SN) (lowest)
What is the visibility in hill fog?
Less than 200m
What are the 3 categories for rain intensity?
Light
Moderate
Heavy
What are the categories for the intensity of icing?
Light
Moderate
Severe
What can be assumed when a CB or TS is forecast?
Mod/severe icing and turbulence
Hail
When avoiding a TS visually how far must you avoid it by?
10nm
If you wish to overfly a thunderstorm by how much must you overfly?
5000ft
What is a front?
Where two air masses of different temp and humidity meet
How fast does a cold front move?
Full geostrophic wind speed
How fast does a warm front move?
2/3 geostrophic wind speed
What does the letters D, N and U mean when associated with RVRs in METARs and TAFs?
D= decreasing N = constant U = increasing
When are wind gusts reported?
When +10kts from mean wind speed
What does CAVOK mean?
No cloud below 5000ft or highest MSA
Vis +10km
No CBS
What does a TEMPO mean?
Less than 1hr in each instance
No more than 50% of forecast period in total
What weather is associated with a cold front?
Unstable weather
CBS
TCUs
Precipitation 50nm either side of front
What weather is expected at a warm front?
Lowering cloud base towards the front Stable CI CS AS NS Precip 200nm ahead of front
