Meteorology Flashcards
Most visible weather phenomenon occurs in the _____
Troposphere
The troposphere goes from ___ up to ~___ also known as the _____
MSL (mean sea level)
~11km (36,090ft)
Tropopause
Temparature decreases at a rate of ___ per 1,000ft (__ per 100m) up to a hight of ___. This is known as the _____ _____
1.98°C
0.65°C
Lapse rate
___ of water vapour is in the troposphere
90%
___ of total mass of air is in the troposphere
75%
ISA Sea level pressure
1013.25Hpa
29.92InHg
760mmHg
ISA Sea level temp
+15°C
ISA Density
1.225Kg/m³
ISA temp 11-20km (36,090 - 65,000ft)
-56.5°C
The composition of air:
78% Nitrogen
21% Oxygen
1% Other Gases
The closer to the poles you are, the _____ the tropopause, at an altitude of aprox. __ -__km
Lower
8 - 10km
The closer to the equator you are, the _____ the tropopause, at an altitude of aprox. __ - __km
Higher
16 - 18km
The closer to the poles you are, the _____ temperature is at the tropopause, aprox. __ to __°C
Higher
-40 to -50°C
The closer to the equator you are, the _____ temperature is at the tropopause, aprox. __°C
Lower
-75°C
Summer tropopause height at Latitude 30°
16km (52,000ft)
Winter tropopause height at Latitude 30°
16km (52,000ft)
Summer tropopause height at Latitude 50°
12km (38,000ft)
Winter tropopause height at Latitude 50°
9km (29.00ft)
Summer tropopause height at Latitude 70°
9km (29,000ft)
Winter tropopause height at Latitude 70°
8km (26,000ft)
Folds in the tropopause are due to
large air masses
ISA = __ - ((Alt/__) x _)
ISA = 15 - ((Alt/1000) x 2
If the actual temperature is warmer than ISA, the deviation is _____
Positive
If the actual temperature is colder than ISA, the deviation is _____
Negative
The Stratosphere extends from the _____ , up to
about ___
Tropopause
50km (164,040ft)
The Stratosphere holds __ of the atmospheres gases
19%
The Stratosphere contains the_____ ______, at __ - __km
Ozone layer
15 - 35km (49,200 - 114,829ft)
The ozone layer _____ UV radiation and emits _____ _____ _____
Absorbs
Long wave radiation
Between 20km and the stratopause, temperature _____ to __
Rises
0°C
The _____ is between the stratopause and __ - __km
Mesosphere
80 - 90km (262,470 - 295,280ft)
You can find ____ but not _____ in the lower stratosphere
Clouds
Turbulence
The _____ between the stratopause and the mesopause falls from __ to __
Temperature
0°C to -90°C
Above the mesopause, you will find the _____ which reaches a height of aprox. ___
Thermosphere
700km
Temperature in the thermosphere _____
Increases
In the thermosphere, you will find the _____ between aprox. ___ - ___
Ionosphere
85 - 600km
Potential difference (v) between the Earths surface and Ionosphere is ___ - ___
250 - 500kv
°C to °F
(°C x 1.8) + 32
°F to °C
(°F - 32) / 1.8
°C to K
+273
°F boiling point
212°F
°F freezing point
32°F
K boiling point
373k
A _____ records temperature over time and plots it on a graph
thermograph
A _____ _____ records surface temperature and humidity, must be placed __ - __ _________
Stevenson Screen
1 - 2m above the ground.
A radiosonde records 3 things:
every __
Air temperature
Humidity
Pressure
1.3 seconds
A radiosonde can reach a hight of ___
35km
Insolation
Amount of solar radiation absorbed per unit area over time
The Earth is tilted on an axis of
23.5°
In January, the Earth is _____ from the sun
91 million miles
In July , the Earth is _____ from the sun
95 million miles
The earth spins
anti-clockwise
Summer solstice
21st June, Northern hemisphere closest to the sun at 23.5°N - the tropic of cancer
Winter solstice
21st December, Southern hemisphere closest to the sun at 23.5°S - the tropic of Capricorn
Spring & Autumn Equinox
23rd March & 23rd September, Sun at same angle as equator.
Conduction
The transfer of heat by physical contact
Convection
The transfer of heat through the vertical
movement of air
Advection
The transfer of heat through the horizontal movement of air
Sublimation
Direct change of a vapour to solid, or solid to vapour
In the day, thick cloud = _____. No cloud = _____
Cooler
Warmer
At night, thick cloud = _____. No cloud = _____
Warmer
Cooler
Inversion
Temperature increasing with height
In the day, wind = _____. No wind = _____.
Cooler
Warmer
At night, wind = _____. No wind = _____.
Warmer
Cooler
_____ reduces non-linearly with height, due to the _____ distribution of the mass of air
Pressure
Non-linear
Colder then ISA, the _____ dense the air
More
Warmer the ISA, the _____ dense the air
Less
Natural inversions
form over night
Fog is caused by the temperature _____ enough to condense the _____ _____ into _____ _____
Cooling
Water vapour
Water droplets
At the bottom of a valley, visibility can be _____ and aircraft performance is _____ due to _____ air.
Poor
Better
Denser
When air is subsiding and diverging it is a _________
High pressure system
The greater the _____ of overlying air, the _____ the atmospheric pressure
Mass
Greater
Pressure reduces by ___ per ___ up to ____
1hPa
27ft (8m)
20,000ft
Low pressure areas are known as
Depressions (lows)
High pressure areas are known as
Anticyclones (highs)
Whenever a pressure variation exists, the _____ created driving the air from high to low _____ is called the ________
Force
Pressure
Pressure gradient force (PGF)
The PGF is the _____ _____ driving the flow of air and _____ the wind speed
Primary force
Determines
Trough lines
Areas of disturbances
Barometric pressure can be measured by 2 devices:
A mercury Barometer
A Aneroid Barometer
What is the QFE?
The isobaric surface pressure at the airfield reference point
What is the QNH?
The barometric pressure measured at the reporting stating which has be mathematically adjusted to MSL using the airfields elevation.
QNH = ___ +- (Elevation/___)
QNH = QFE +- (Elevation/27ft or 8m)
There is a __ height difference for every __ of ISA deviation
4%
10°C
Height
The indication above ground level, normally the height above an aerodrome QFE reference point.
Altitude
The indication above MSL
Flight levels use the pressure setting of
Mean Sea Level (1013pHa)
When the altimeter is indicating a reading lower than the true altitude it is
Over reading
When the altimeter is indicating a reading heigher than the true altitude it is
Under-reading
Cold air: _____ altitude < _____ altitude
True
Indicated
Warm air: _____ altitude < _____ altitude
Indicated
True
The barometric lapse rate
27ft per 1hpa
To determine the IA change use the equation
IA change (ft) = Difference in hPa x 27ft
Most dangerous - “____ to ____, look out below”
High
Low
Most dangerous - “____ to ____, don’t be bold”
Hot
Cold
Equation to calculate Temperature Error Correction
((ISA Devation/10) x 0.04) x altitude
OR
(4 x (Altitude/1000)) x ISA devation
Equation to calculate ISA Deviation
15 - ((alt/1000) x 2)
If an aerodrome elevation is given in the question
It must be taken into account
Due to the _____ effect, _____ occurs over the crest of high terrain, causing air speed to _____, and _____ and _____ to decrease.
Venturi Convergence Increase Pressure Temperature
In controlled airspace, controllers assign levels to ___ flights to provide _____ _____.
IFR
Terrain Clearance
Controllers have no responsibility for the _____ _____ for ____ aircraft.
Terrain Clearance
VFR
In temperatures warmer than ___, FL separation _____
ISA
Increases
In temperatures colder than ISA, FL separation _____
Decreases
What is the definition of Density ? And what is ISA density at sea level
Measure of a mass of air within a given volume.
1.225 Kg/ m3
Under ISA, 1/2 and 1/4 of MSL density occurs at what altitude?
22000 FT and 40000 FT
Density in the atmosphere is affected by
Pressure
Temperature
Humidity
The density decreases with altitude, but at a ______-______ rate. It reduces more quickly at ________ altitudes. Mimicking the pressure lapse rate with height.
Non-linear
Lower
What are the 4 main steps of the hydrological cycle
Evaporation, Condensation, Precipitation, Run-off
On average there’s approx. ___% of water vapour in the atmosphere. But it can vary from 0 to ___% . 90% of the water vapour is found in the __________
1, 5, troposphere
Humidity mixing ration tells you how much water vapour is actually in the air, it is measured in ____ of water vapour per ____ of dry air
Grams, Kilograms
g/Kg
Humidity mixing ratio won’t change unless……
You add/ remove water vapour
Saturation mixing ratio is the ______ amount of water vapour that can be in the air for a given temperature
Maximum
Warmer air can potentially ‘______’ more water vapour than colder air
Hold
Saturation mixing ratio ______ with increasing altitude and decreasing temperature. Whereas humidity mixing ratio ______ ______ constant as altitude increase and pressure and temperature decrease
Decrease
Stays constant
The ratio between the amount of water vapour that the air is holding and the maximum amount of water vapour that air can hold is called?
Relative humidity
At constant pressure, relative humidity is affected by……
Amount of water vapour
Temperature
Assuming pressure is constant throughout a clear day, what is the RH like to be _______ 30 mins after sunrise and ______ 2-3 hours after noon.
Greatest
Least
The close the ambient air temperature is to the ______ ______ temperature, the higher the humidity
Dew point
Formulas for relative humidity, using temperature and dew point
RH % = 100 - (5x (T - Td))
% difference between the dry bulb temperature and wet bulb temperature is equal to?
Relative Humidity
What is the DALR?
How does it change with height?
Dry adiabatic lapse rate
3 degrees per 1000 FT/ 1 degree per 100 m
What is SALR?
And how does the temperature vary with height?
Saturated adiabatic lapse rate
1.8 degrees per 1000 FT / 0.6 degrees per 100 m
A parcel of saturated or dry air is said to ________ ________ if it is cooler than the environment. it will sink back down to its original level even when forced to rise
Absolutely stable
ISA ELR is?
2 degrees per 1000 FT / 0.65 degrees per 100 m
When an air parcel is rising and subsiding along the saturated adiabatic lapse rate, the RH must ______ ______, until ______ ______ is removed from the parcel.
Remain constant (at 100%).
Water vapour
The ______ the saturated air, the ______ it cools, because warmer saturated air holds ______ moisture than cold saturated air,
therefore ______ condensation will take place when it is cooled, but more ______ ______ will also be released.
Warmer, slower, more, more, latent heat
The SALR increases ______ with height
Exponentially
Low pressure systems are known as
Cyclones or depressions
Low pressure are always accompanied by _____ and _____
Cloud
Precipitation
Low pressure systems have isobars that are _____ _____ than other systems.
Closer together
In Low pressure systems, air flows _____ in the Northern Hemisphere and _____ in the Southern Hemisphere
Anti-clockwise
Clockwise
As air rises, it _____, causing water vapour to _____ and _____ _____ with possible _____
Cools
Condense
Form clouds
Precipitation
With your back to the wind in the Northern Hemisphere, the low pressure system is to your _____
Left
Small scale low pressure systems can be ___ to ___NM across and usually occur over _____
1 to 20NM
Land
Large scale low pressure systems can be ___ to ___NM across
300 to 1000+NM
Small scale warm, lows can _____ during the day over land masses in _____.
Develop
Summer
Warm lows are low pressure systems in which the _____ is _____ than the surrounding environment
Core
Warmer
Warm lows can produce 3 things:
Heavy rain
Thunder Storms
Flash Floods
Large thermal lows usually form over land in summer where the _____ is present
Inter-tropical Convergence Zone (ITCZ)
In July the ITCZ is in the _____ hemisphere and ranges from latitudes ___ to ___
Northern
15-20°N
In January the ITCZ is in the _____ hemisphere and ranges from latitudes ___ to ___
Southern
0-20°S
When the ITCZ moves it affects local _____ _____ and has a large effect on the _____
Tropical winds
Inland Water warm depressions can form over _____ in winter, when colder air over _____, moves over warmer _____ or _____.
Water
Continents
Seas
Lakes
Small but intense maritime meso-scale cyclones that form in in winter, by cold polar or arctic air advected over relatively warmer water.
Polar lows
Low pressure systems in which the entire core is colder than the surrounding environment
Cold lows
Cold lows can produce 5 things:
Snowfall Thunderstorms Heavy rain Floods Windshear
Cold depressions are typically _____ _____ and move with medium airflow at _____ to _____ft.
Frontal depressions
2,000 to 3,000ft
A low-pressure area which forms in the lee of mountains
Orographic Depression
With a strong wind blowing at approx. ___ towards a mountain range at, the wind will tend to blow _____ ___ _____ of the mountain rather than _____ ___ _____
90°
Around the side
Over the top
Isobaric troughs indicate
An area of low pressure going into another system
Trough lines indicate
Areas of stronger surface convergence
High pressure systems are also known as
Anticyclones
An anticyclone is
an area of relatively high surface pressure.
Air is _____ in a high pressure system
Subsiding
As the air _____ it warms due to _____ and so cloud formation is _____, causing the weather to usually be settled with only _____ amounts of cloud cover
Subsides
Compression
Inhibited
Small
High pressure systems can be up to ____NM and are _____ _____ _____
1500NM
Slow moving systems (quasi-stationary)
Warm highs
High pressure systems in which the entire core is warmer than the surrounding environment
Pressure levels are pushed _____ in the core due to excess air in the upper troposphere as the warm air _____
Higher
Rises
Warm High pressure systems can produce 4 things:
Heatwaves
Drought
Poor air quality
High pollen count
High pressure areas are associated with _____ _____
Light winds
High pressure systems usually occur around
30°N/S
Cold highs
High pressure systems in which the entire core is colder than the surrounding environment
In high pressure systems air flows _____ in the Northern Hemisphere and _____ in the Southern Hemisphere
Clockwise
Anticlockwise
Due to the colder, _____ air, the pressure levels bulge _____ at higher altitudes
Heavier
Downwards
Cold High pressure systems can produce 6 things:
Droughts Frosts Snowfall Mist/Fog Low level cloud Poor air quality
Cold anticyclones are permanently found over the _____ know as _____ _____.
Poles
Polar Highs
Blocking high
Highs that can become stronger in summer, pushing lows around them
Blocking highs are _____ and between __ and __
Quasi-stationary
50° and 70°
Ridges are indicated by _____ extending out from the area of _____ pressure
Isobars
High
Cols
An area of relatively high pressure shown on a synoptic chart, situated between two areas of higher pressure and low pressure
Flat-Pressure Patterns
An area clear of isobars
The 3 cells from the poles to the equator
Polar cell
Ferrell cell
Hadley cell
The polar cell ranges from the latitudes ___ and ___
90°
60°
The Ferrell cell ranges from the latitudes ___ and ___
60°
30°
The Hadley cell ranges from the latitudes ___ and ___
30°
0°
At 90° you can find _____ pressure
High
At 60° you can find _____ pressure
Low
At 30° you can find _____ pressure
High
At 0° you can find _____ pressure
Low
Warm high pressure regions:
Azores high, 1020hPa, (all year)
Pacific high, 1020hPa (all year)
Cold high pressure regions:
Siberian high, 1035hPa (Jan)
Canadian high 1020hPa (Jan)
Warm Low pressure regions:
North Australian low, 1005hPa (Jan)
Asian low, 1000Hpa (July)
North American low, 1010hPa (July)
Cold Low pressure regions:
Icelandic low, 1000hPa (Jan)
Aleutian low, 1000hPa (Jan)
Icelandic low split, 1010hpa (July)
Density
Measure of a mass of air within a given volume (kg/m3 or gm/m3)
As altitude increases, density _____ at a _____ rate
Decreases
Non-linear
In ISA conditions atmospheric density is at 3/4 of MSL at _____, 1/2of MSL at _____ and 1/4 of MSL at _____
10,000ft
22,000ft
40,000ft
If pressure decreases, the mass of air within the same given volume _____
Decreases
More humid air is _____ _____ than than dry air
Less dense
In cold air density decreases ______ with height than warm air.
quicker
Equation for pressure difference:
PA diff = 120ft x ISA temp devation
If colder, it will be a ______ pressure difference. If warmer, it will be a _____ pressure difference.
Negative
Positive
There is __% of water vapour in the atmosphere
1%
Warm, air can hold _____ water vapour than cold air.
More
The HMR (Humidity mixing ratio) tells you:
How much water vapour is actually in the air measured in g/kg (or kg/kg)
The HMR’s value won’t change unless you _____ or _____ water vapour from the air:
Add
Remove
The MR is constant as altitude _____ and pressure and temperature _____
Increases
Increase
The SMR (Saturation mixing ratio) is:
the maximum amount of water vapour that can be in the air at a certain temperature, measured in g/kg (or kg/kg)
The SMR _____ with increasing altitude and decreasing temperature
Decreases
Relative humidity equation:
RH% = (HMR/SMR) x 100
At a constant pressure the RH is affected by the:
Amount of water vapour
Temprature
The RH is
The ratio (%) between the amount of water vapour that the air is holding, and the maximum amount of water vapour that the air can hold.
The RH is greatest ____________ and weakest ____________
30 mins after sunrise
2-3hrs after midday.
The closer the ambient air temperature to the dew point temperature, the _____ the humidity and the further away the ambient air temperature to the dew point temperature, the _____ the humidity
Higher
Lower
The dew point
The temperature, to which the air must be cooled for it to become saturated and start to condense
Equation to calculate RH with the dew point:
RH% = 100 - (5x (T - TD)
A Psychrometer is used to determine 3 things:
Temprature
RH%
Dew point
Adiabatic
A process that occurs without the transfer of heat or matter with the surroundings
DALR
-3°C per 1,000ft (-1°C per 100m )
SALR
-1.8°C per 1,000ft (-0.6°C per 100m)
In the tropics SALR can be _____ and in Polar regions it can be _____
- 4°C per 100m
0. 9°C per 100m
Absolute stability is when
ELR < Both DALR & SALR (they subside)
Absolute instability is when
ELR > Both DALR & SALR (they rise)
Conditional stability is when
DALR (Subsides) > ELR > SALR (rises)
Neutral Stability is when
ELR = DALR or ELR = SALR
If cooled from below, the air is _____, if warmed from below, the air is _____.
Stable
Unstable
Clouds form when the invisible water vapour in the air, _____ onto microscopic nuclei, becoming ___________ or __________
Condenses
Visible water droplets
Ice crystals
Cumulus clouds from through _____ when the atmosphere is _____
Convection
Unstable
A front is where ____________, here _____ air rises over _____ air.
2 air masses meet
Warmer
Colder
On a warm front you can find:
Stratus and Cirro clouds
On a cold front you can find:
Cumulus clouds
A cold front is _____ lifting and moves _____.
Steeper
Faster
The quicker a front is moving, the ______ _____ the uplift.
More instense
Unstable orographic uplift is when air is forces to rise by _____ and _____. The air then continues _____.
Mountains
Convects
Upwards
Stable orographic uplift is when the _____ effect takes place. _____ takes place decreasing the _____ _____. Air then _____ on the lee side.
Foehn
Precipitation
Dew point
Descends
Convergence is when
Two air masses coming from different directions meet and are forced to rise.
Turbulent layers are formed by
Air blowing over solid objects such are buildings, trees and hills.
Turbulent layers tend to form up to a depth of about
2,000-3,000ft
If the _____ _____ is reached within the turbulent layer, _____ will form at the top of the layer
Dew point
Cloud
Inversions cause an increase in _____ and _____ the upward growth of cloud by preventing further _____
Stability
Limit
Convection
Oktas leves: Few - Scattered (SCT) - Broken (BKN) - Overcast (OVC) -
1 - 2
3 - 4
5 - 7
8
Cloud base
The height of the base of the cloud is measured above ground level in ft. measured by a Ceilometer
Cloud base equation:
Cloud Base Height ft = Temp. − Dew Point X 400
The height above the ground or water of the base of the _____ layer of cloud below _____ covering more than _____ the sky
Lowest
20,000ft (6,000m)
Half
Vertical visibility is used
When the sky is obscured by precipitation, and cloud details cannot be assessed but information on vertical visibility is available.
High level clouds: name group
Cirro
High level clouds: Polar altitudes
3-8km (10,000 - 25,000ft)