Moist adiabatic processes

temperature fall and water vapor condensation that makes the rate of the temperature fall less than 1°/100 m.

So, Ti0, RH<100%

Initial level

Lifting Condensation level

The rate of temperature variation of the ascending saturated air without heat influx or outflow is called MOIST ADIABATIC LAPSE RATE

air decreases with height, but slower that at dry adiabatic process ( ).
Due to condensation, the particle specific humidity Sm decreases with height
Relative humidity remains equal to 100%.

Adiabatic ascent of the moist air till attaining saturated state is called DRY STAGE.
Further ascending of the saturated air above the condensation level is called MOIST STAGE

Condensation level

Dry stage

Moist stage

of the saturated air has got some amount of heat dq. This heat will be laid out for:
Inner energy increase
Expansion work
Evaporation of some amount of water
Reason for evaporation

The parcel becomes non-saturated +

evaporation

As we know,

adiabatic lapse rate depends on pressure and temperature only and does not depend on humidity

pressure

air

Unstable atmosphere

Stable atmosphere

Neutral atmosphere

Moist, saturated air

Absolute instability

Absolute stability

Conditional instability

The air is unstable, it is saturated

Combine criterion of instability

parcel, the water vapor containing in it had been condensed due to adiabatic ascent and the heat obtained has been laid out to rise up the air parcel temperature,

Θ, e

Θ+dθ, e=0

Θe, e=0

1000 hPa

Equivalent-potential temperature

Θp.p, e=0

Initial level

Pseudo-potential temperature

temperature and the humidity. Θp.p is the temperature that an air mass package will have after condensation and falling out of all water vapour due to upward motion followed by dry adiabatic downward motion to the starting position. In practise the combination of Θp.p and the wind barbs should be used.

Θ, e

Θ+dθ, e=0

Θe, e=0

1000 hPa

Equivalent-potential temperature

Θp.p, e=0

Initial level

Pseudo-potential temperature