Conditionally unstable

[gerardflyagain]

Can anyone explain the answer below please? If we assume dlr and slr at 3 and 1.5 respectively, surely the air is stable? Because in both cases the parcel is cooling per 1000ft, but the outside air temperature is warming?

If the temp at 1000ft is +18 and the temp at 2000ft is +20, what would you expect the air between those altitudes to be?

✓ Conditionally unstable

[foxmoth]

I think they must have got the height/temps the wrong way round!

[Jan Olieslagers]

Which were the other options?

@FoxMoth: you may well be right, but couldn't this be a case of temperature inversion, too?

[The Ancient Geek]

Inversions are interesting beasties. They are normally very stable and can cause fog to lie in a valley for several days. A bad case was the London smogs of the 1950s which caused many fatalities.
The hot upper layer can contain a lot of moisture and the arrival of some turbulence to cause mixing will make life rather interesting rather quickly.

[gerardflyagain]

I can't remember the other options I'm afraid.

[foxmoth]

FoxMoth: you may well be right, but couldn't this be a case of temperature inversion, too?

Yes, but that would make the answer wrong as an inversion is stable.

[foxmoth]

Air is conditionally unstable if, when it becomes saturated, it becomes unstable.

No, it is dependent on the actual conditions - in the origional post if the temp at 1,000' is 20 and at 2,000 it is less than 17 then it will be unstable, 2,000' temp warmer than 18.5 and the air is stable, it is only when the ACTUAL lapse rate is between 1.5 and 3 (i.e., in this example temp at 2000' is between 17 and 18.5) that it is conditionally unstable.