1. If a dry air parcel is displaced upward in a stable atmosphere, what happens to the parcel when it is released?
a. It returns to its original position
b. It remains where it is
c. It accelerates upward
Correct. A stable air parcel always seeks to return to its original position, regardless of whether the initial displacement is up or down.
Incorrect. A displaced parcel that remains where it is after being displaced indicates a neutral atmosphere.
Incorrect. A displaced parcel that accelerates away from its original position after some initial displacement indicates an unstable atmosphere. In an unstable atmosphere, a parcel displaced downward accelerates downward while a parcel displaced upward will accelerate upward.
2. If a dry air parcel is displaced upward in an unstable atmosphere, what is the virtual temperature of the parcel relative to the ambient virtual temperature?
a. Tv (parcel) > Tv (ambient)
b. Tv (parcel) = Tv (ambient)
c. Tv (parcel) < Tv (ambient)
Correct. The parcel will become warmer than its environment and thus positively buoyant.
Incorrect. If the virtual temperature of the parcel and its environment are the same, then they have the same density. This indicates a neutral atmosphere.
Incorrect. A parcel that cools relative to its environment when displaced upward becomes negatively buoyant. This indicates a stable atmosphere.
3. If a dry air parcel is displaced upward in a dry, neutral atmosphere, what is the potential temperature (theta) of the parcel relative to the ambient potential temperature?
a. Theta (parcel) > Theta (ambient)
b. Theta (parcel) = Theta (ambient)
c. Theta (parcel) < Theta (ambient)
Incorrect. Theta does not vary with height in a neutral environment and a displaced parcel maintains a constant theta, so long as it remains unsaturated. A parcel theta greater than the ambient theta indicates positive buoyancy and an unstable environment.
Correct. Theta does not vary with height in a neutral environment and a displaced parcel maintains a constant theta, so long as it remains unsaturated.
Incorrect. Theta does not vary with height in a neutral environment and a displaced parcel maintains a constant theta, so long as it remains unsaturated. A parcel theta less than the ambient theta indicates negative buoyancy and a stable environment.