Question

Sounding plotted on skew-T diagram

The lapse rate in the 900-800 hPa layer may be described as:
(Choose all that apply then click Done.)
a) stable
b) unstable
c) conditionally unstable
d) dry adiabatic
e) moist adiabatic
f) isothermal

The correct answers are (a) and (f). The temperature is constant within the layer, so the lapse rate is isothermal. An isothermal lapse rate is also an absolutely stable lapse rate.

If the layer is lifted 100 hPa, what is the temperature (T′) at the bottom of the layer?
T′ = °C      
The correct answer is 15°C. Since conditions are saturated, the temperature follows a moist adiabat from 900 to 800 hPa.

What is the temperature (T") at the top of the lifted layer?
T" = °C      
The correct answer is 9°C. Since conditions are unsaturated, the temperature follows a dry adiabat from 800 to 700 hPa.

Is the layer more stable or less stable after being lifted?
More stable
Less Stable
The correct answer is less stable. Before lifting, the layer was isothermal and hence stable. After lifting, the temperature decreases 6°C over 100 hPa and the layer is conditionally unstable.
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