Moisture In The Atmosphere Flashcards
What are the 4 key factors of Evaporation?
- The amount of moisture the air contains
- The availability of moisture
- The availability of heat energy
- Wind speed
Define Partial Pressures
Each element adds partial pressure to the total as a result of moisture in vapour form
Define Vapour Pressure and what is its symbol?
The amount of water in the air that exerts a partial pressure.
Symbol = e
Define the Saturated Vapour Pressure and what is its symbol?
The maximum amount of water vapour the air parcel can hold (this increases with temperature)
Symbol = es
What must be true for saturated air?
e=es
What is humidity?
An indicator of how much moisture is in the air
What is the dew point and the symbol?
At a constant pressure is where condensation occurs and dew forms at that temperature.
Symbol = Td
What does a high dew point indicate?
Moist Air
What does a low dew point indicate?
Dry Air
What is the Adiabatic Processes?
- No heat energy is exchanged between the air and parcels outside of the air.
- The air parcel rises and does work
- The air parcel cools and SVP decreases as internal heat energy is lost
- Eventually condensation occurs when e=es
- Opposite occurs for descending air
What is the 1st Law of Thermodynamics?
The conservation of energy.
Change in heat (dq) = changes in internal energy (du) + changes in work done (dw)
For adiabatic processes dq = 0
Features of Stable Air
Cold, dry air below, forced convection, stratiform clouds
Features of Unstable Air
Warm, moist air below, free convection, cumuliform clouds
Potential instability occurs when…
A lager of air has an unsaturated top and a saturated bottom causing a flip and downpours
What is the dry adiabatic lapse rate?
9.8 degrees C / km
