Humidity & Stability Flashcards
The term that defines different characteristics between bits of air
PARCEL OF AIR
The measure of how much water content is contained within a parcel of air
HUMIDITY
If there is more water vapour per parcel of air, it is said to be what
MORE HUMID
The amount of weight of water vapour per parcel of air is known as what
ABSOLUTE HUMIDITY
Ability for air to contain water vapour is dependant on what 2 factors
- Pressure
- Temperature
The biggest influence on humidity is what
TEMPERATURE
The amount of water vapour per parcel of air expressed as a percentage
RELATIVE HUMIDITY
The term used when a parcel of air reaches 100% humidity
SATURATED
Cannot carry any more water vapour
what is the relationship between relative humidty and the volume of water vapour
Amount of water vapour generally remains the same
Relative humidity depends on temeprature
Parcel cools, relative humidity INCREASES
Parcel heats, relative humidity DECREASES
What happens to water vapour when 100% humidity is reached
CONDENSES
rain, cloud, mist
What is the dew point
Temperature at which 100% relative humidity occurs in a parcel of air
A means to measure ELR in the atmosphere
RADIOSONDE BALLOON
What does DALR stand for
What does it measure
What are teh rates (ft and m)
- Dry Adiabtic Lapse Rate
- Lapse rate of DRY AIR
- -3℃ per 1000 ft / -1℃ per 100m
What does SALR stand for
What does it measure
What are the rates (ft and m)
- Saturated Adiabatic Lapse Rate
- Lapse rate of saturated air (100% humidity)
- -1.8℃ per 1000ft / -0.6℃ per 100m
What is the lapse rate of DALR in meters and feet
- -3℃ per 1000 ft
- -1℃ per 100m
What is the lapse rate of SALR in meters and feet
- -1.5℃ per 1000ft
- -0.6℃ per 100m
-1.8℃ per 1000ft in ATPL
What is the adiabatic process from gas to solid and solid to gas
GAS – gives energy –> LIQUID – gives energy –> SOLID
SOLID – requires energy –> LIQUID – requires energy –> GAS
Vapor DIRECTLY to solid = Deposition
Solid DIRECTLY to Vapor = Sublimation
What is ELR
ENVIRONMENTAL LAPSE RATE
What state is a parcel of air if it is cooling SLOWER than the surrounding atmosphere
ABSOLUTE INSTABILITY
Parcel of air cools at a lesser rate than ELR
In ascent its temperature increases relative to the surrounding air
Parcel does not resist vertical motion
REMEMBER Urban District Councils Shovel Shit
In relation to vertical movement, how will a parcel of air with absolute instability behave
DOES NOT RESIST VERTICAL MOTION
Will rise quickly and accelerate
What state is a parcel of air if it is cooling more quickly than the surrounding atmosphere
ABSOLUTE STABILITY
SALR is LESS than ELR i.e. -1.5℃ < -1.0℃
Parcel of air will not rise as its temperature is cooler than surrounding atmopshere
It sinks down
Parcel of air resists vertical movement
In relation to vertical movement, how will a parcel of air with absolute stability behave
RESIST VERTICAL MOTION
Will sink back down and resist rising
If a parcel of air’s lapse rate is between the DALR and SALR, what state is it said to be in
CONDITIONAL INSTABILITY
If DALR = -3℃ and SALR = -1.5℃
ELR would be (for example) -2℃
DALR < ELR < SALR
What is the process of a parcel of air warming as it descends
ADIABATIC WARMING
What is the process of a parcel of air cooling as it ascends
ADIABATIC COOLING
The following are signs of what sort of stability
Occurs by atmospheric heating from below
Air moves vertically upwards
Cumulous or heaped type clouds
Turbulent flying conditions
Showers, heavy rain, but good visibility
INSTABILITY
The following are signs of what sort of stability
Occurs by atmospheric cooling from below
Vertical movement but limited to lower layers i.e. vertical movement stops
Stratus or layer type clouds covering large areas
Smooth flying conditions
Precipitation can last for a long time
Visibility can be poor
STABILITY
The 2 sides of a hill or mountain are known as what
Which side is warmer
LEE SIDE & WINDWARD
WARMER lee side > windward COLDER
