Chapter 8 - Stability Flashcards
What is the adiabatic process?
A parcel of air in the atmosphere can heat up or cool down without any transfer of energy. This is caused by it expanding or compression.
i.e A parcel of air rises - it expands and cools
What is the ELR lapse rate according to ISA
- 98 degrees per 1000 ft
0. 65 degrees per 100m
What is the DALR? with figures
Dry adiabatic lapse rate
3 degrees / 1000ft
1 degrees / 100m
What is the SALR? with figures
Saturated adiabatic lapse rate
- 8 degrees / 1000ft
- 6 degrees / 100m
Why is the SALR smaller?
because the parcel of air is saturated - when it cools more it start to condense. If it’s condensing the its releasing latent heat which keeps the air in the parcel warmer.
SALR can vary with temperature a lot why?
Because warm air can hold more water vapour than cold. if more WV = condensing = more latent heat = smaller LR
If less WV condensing - increases exponentially with height.
If the parcel of air subsides and sinks =
Stability
Neutral stability =
When either the DALR or SALR are cooling at exactly the same as the environment
Absolute instability =
is when the ELR is greater than the DALR and SALR
What weather condition are associated with absolute instability? For Cloud, Precipitation, Vis, Turb, press systems?
Cloud = cumulative Precipitation = showers Visibility = Good out of showers Turbulence = moderate to servere Pressure systems = Low/depression/ cyclone
Absolute stability =
is when the SALR + DALR are greater than the ELR therefore making them sink creating stability
What weather condition are associated with absolute stability? For Cloud, Precipitation, Vis, Turb, press systems?
Cloud = Stratiform Precipitation = Drizzle Visibility = Low Turbulence = light to moderate Pressure systems = High/ anti cyclone
Conditional instability =
Occurs when it doesn’t matter if the air is dry or saturated. The air is stable or unstable depending on whether it is dry or saturated
What does a Tephigram show?
Shows the amount of energy in the air - its stable or unstable
What are the lines on a Tephigram showing?
Px levels Temperature DALR SALR Dew point
