Stable Air [5 points] 2. An air parcel is considered to be stable when it tends

Question

Stable Air [5 points]

2. An air parcel is considered to be stable when it tends to return to its original position in the atmosphere after it has been set in vertical motion due to some sort of forcing mechanism, once that forcing has been removed (i.e., it is an air parcel that, left alone, would tend not to move vertically). Air is stable when the Environmental lapse rate (ELR) is less than the Dry Adiabatic Lapse rate (DALR). Note the ELR will vary from place to place, while the, DALR, the rate at which a parcel cools when lifted, is a constant for dry (unsaturated) air.

In the questions below, the “Steps” are simply for your own use in computing answers to a, b, etc. Further, be sure your numeric responses are mathematically supported: e.g., if the ambient atmosphere started at a temperature of 20 °C, and the ELR was 9°C/1000m, then if you ascend 2000 m, you have lost 18°C (2 x 9 °C) and reached an ambient temperature of 2 °C.

Step 1: Draw a line through point A on the chart of temperature vs. height (Graph A) to represent an ELR of 9 °C/1000m. Do not hand in the graph – this is for your own use!

a) If an air parcel is forced to rise from Point A, what would be its rate of cooling if it remains dry? [1 point] Step 2: Draw a line on Graph A to show this rate of cooling with altitude.

b) Is the rising parcel of air cooler or warmer than the ambient atmosphere at the same altitude above (not at) Point A? You can assume the parcel was at the ambient air temperature when it started out. [1 point]

c) What is the difference in temperature between the rising air parcel and the ambient atmosphere at an altitude of 5000m? [2 points]

d) If the impelling force were to be removed, would the air parcel tend to return to its original position (Yes/No)? [1 point]

Explanation / Answer

a) When the air parcel is forced to move up from point A at a state of being dry,it would cool at the rate of 9.8 °C/1000m

b)The rising parcel is cooler than the ambient temperature.

c)There will be a difference of -4°C between the rising parcel and ambient atmosphere.at an altitude of 5000m.

d)The air parcel being cooler than its surrounding will tend to return to its original position if the impelling force is removed.

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.