ON the basis of the average temperature gradient in the situations described, cl

Question

ON the basis of the average temperature gradient in the situations described, classify the degree of stability (unstable, neutral, or stable) of the atmosphere.

(a) temperature at ground level is 70 F, temperature at 1500 ft is 80 F
(b) ground-level temperature is 70 F, temperature at 2500 ft is 60 F
(c) ground-level temperature is 60 F, temperature at 1900 ft is 48 F
(d) ground-level temperature is 25 C, temperature at 2000 m is 5 C
(e) ground-level temperature is 30 C, temperature at 500 m is 20 C
(f) ground-level temperature is 25 C, temperature at 700 m is 28 C

An explanation of how to determine the stability given the two different altitudes and temperatures would be super helpful. Thanks!

Explanation / Answer

DRY ADIABATIC LAPSE RATE.—If  a  parcelof  air  is  lifted,  its  pressure  is  DECREASED,  sincepressure decreases with height, and its temperature falls due to the expansion. If the air is dry and the process isadiabatic,   the   rate   of   temperature   fall 5 l/2°F per 1000 feet  of  lift

The vertical air temperature distribution in the atmosphere is highly variable. For dry air it ranges as follows:

a)increase of 10degree F per 1500 ft increase in height --> 6.66 degree F per 1000ft increase in elevation i.e more than Dry adiabatic lapse rate => Unstable ( Case 4 in above details)

b) 10 F decrease per 2500 F --> 4 F decrease per 1000ft increase i.e less than  Dry adiabatic lapse rate & Temperature decreases with height => Stable (Case 2)

c)12 F per 1900 ft --> 6.315 F decrease per 1000ft increase i.e more than  Dry adiabatic lapse rate & temperature decrease with height => Unstable (Case 4)

d) 20 C decrease per 2000m --> 20F decrease per 6561.68ft--> 3.0479 decrease per 1000ft i.e less than Dry adiabatic lapse rate => Stable (case 2)

Explanation: Change(increase / decrease) in degrees =  Change(increase / decrease) in fahrenheit ; Have a look at conversion formula of C to F if needed. I used google for m to ft conversion.

e) 10 C Temperature decrease per 500m --> 10F per 1640.42 --> 6.095 C Temp decrease per 1000ft > Dry adiabatic lapse rate => Unstable

f)3 C increase per 700m increase --> "plus" temperature lapse rate, or an inversion.

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