• Condensation and Freezing of water in the atmosphere
2) CCN = cloud condensation nuclei
4) Homogeneous condensation occurs at relative humidity values greater than 440%. Condensation upon CCN, heterogeneous condensation, occurs at much lower relative humidity values.
5)The rate of evaporation increases as the size (radius) of a drop decreases.  This means that if a drop is to be in a state of equilibrium (neither grow in size or shrink in size) the relative humidity must be greater than 100%.  This discourages the formation of very small drops.
The second compilation is with respect to the purity of the water.  CCN that will dissolve in water and form a solution actually lower the rate of evaporation from the liquid water.  Thus for a drop to be in equilibrium, this solution effect will reduce the relative humidity needed for the drop to neither shrink or grow in size.
6)Pure liquid water can be cooled to -40C before it freezes.

• Cloud Formation
5) The rate of cooling for "dry" air is dependent upon the mixture of gases in the parcel and these are invariant with respect to location and time.  So, the "dry" rate is the same for Northern Canada and Southern Florida.  The saturated cooling rate is dependent upon the amount of water vapor that condenses.  In class we discussed how for high temperatures the rate of condensation is larger since there is more water vapor in warm saturated air than in cold saturated air.  Thus, the latent heating is larger, and the net cooling rate is slower for warm air than for the case of lower temperatures.  So, the saturated cooling rate for Northern Canada would be greater since the temperature would be less than the temperature for Southern Florida.
6) The temperature is equal to the dew point when the air is saturated, so we want the parcel to be cooled to 0C.  This means we must cool the air 25-0=25 C.  The air parcel starts out unsaturated, so the cooling rate is 10C/km.  Thus the parcel would need to be lifted
(25 C)/(10 C/km) = (25 C)/(10 C) x 1 km = 2.5 km.
The condensation level is defined as the elevation at which a parcel of air would first be saturated if it was lifted from the surface and cooled at the dry adiabatic lapse rate.  So, the parcel is first saturated 2.5 km above the surface and the elevation of the surface in Tucson is ~0.8 km, so the elevation of the Condensation Level would be 0.8 km + 2.5 km = 3.3 km above sea level.

   8) The first table is for the parcel as it travels up the mountain on the west side.
       Altitude (km)        Parcel Temp.        Parcel Dew Point.
            0                        30 C                        20 C
            1                        20 C                        20 C    <<<< LCL
            2                        14 C                        14 C
            3                        8 C                            8 C   - now at the top of the mountain

      This next table is for the parcel as it travels down the east side of the mountain
       Altitude (km)        Parcel Temp.        Parcel Dew Point.
            3                        8 C                        8 C     -- the parcel is saturated AND there are liquid droplets (a cloud) which provide a source
            2                        14 C                    14 C         of water vapor via evaporation as the parcel travels down the mountain and warms up.
            1                        20 C                    20 C     <-Now all the cloud drops have evaporated since the dew point of the parcel is equal to
            0                        30 C                    20 C        the original value (what we started with journey with).  So from here on the rate of warming
                                                                                  would be the dry rate (10 C/km).
The end result is that the air on the east side of the mountain has the same temperature and dew point as the air on the west side of the mountain.
 

   9) Now whenever condensation occurs, the liquid water is lost from the parcel via precipitation.
       The first table is for the parcel as it travels up the mountain on the west side.
       Altitude (km)        Parcel Temp.        Parcel Dew Point.
            0                        30 C                        20 C
            1                        20 C                        20 C    <<<< LCL
            2                        14 C                        14 C
            3                        8 C                            8 C   - now at the top of the mountain

      This next table is for the parcel as it travels down the east side of the mountain
       Altitude (km)        Parcel Temp.        Parcel Dew Point.
            3                        8 C                            8 C  --- since there is no source of water for evaporation, the warming rate will be the dry
            2                       18 C                           8 C       rate of 10 C/km, and the dew point will not change.
            1                       28 C                           8 C
            0                       38 C                           8 C
In this case the air on the east side is warmer and drier than the air on the west side since condensed water left the parcel via precipitation.  As a matter of fact, the air at 0 km on the west side had a relative humidity of (14g/kg)/(26.g/kg)*100% = 53%, while the air on the east side at 0 km has a relative humidity of (6.2g/kg)/(42.2g/kg)*100% = 15 %.

As mentioned earlier, the real atmosphere is somewhere in between the cases a) and b).
 
 

• Stability of the Atmosphere
2) The net force is equal to the difference in density of the surrounding fluid and the object.
4) The buoyant force is proportional to the weight of the displaced fluid.  This does not change due to condensation.
The weight of the parcel is proportional to the density of the parcel.  This decreases since the latent heat given off by the water during condensation is absorbed by the air in the parcel and thus increasing the temperature of the parcel.
The net force is proportional to the difference between the density of the displaced fluid and the density of the parcel.  This difference is increased by the release of latent heat.  So the net force would be greater.
7) The level of free convection is the level at which an air parcel would become buoyant due to the fact that the parcel is warmer than the environmental air.  At this level the parcel would be "free" to "convect" (rise).
• Precipitation

a) condensation - drops are first formed via condensation and also during the ice-crystal process
b) ice-crystal process - since the saturation mixing ratio over ice is lower than over liquid water, water will tend to evaporate from the liquid droplets and condense upon ice crystals.  The number of ice-crystals is less than the number of liquid droplets, so this process tends to move the water from many liquid drops to a few ice-crystals and thus concentrate the water into relatively big ice-crystals.
c) accretion - this specifically refers to ice-crystals freezing super cooled water droplets when coming in contact with them as the two fall through the atmosphere.