Environmental Science: Numerical Questions – Air (Inversion Layer and Stability)

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Type 1 – Inversion Layer (Temperature)

Q1) At a given urban location, the temperature at an elevation of 25 m above ground is 15 °C. If the inversion conditions prevail and the environmental lapse rate is 1.25 °C per 100 m, the temperature at an elevation of 200 m will be

(1) 12.5 °C

(2) 17.5 °C

(3) 12.75 °C

(4) 17.25 °C

Answer: (4) 17.25 °C

Temperature at an elevation of 25 m above ground is = 15 °C

Environment Lapse Rate – 1.25 °C per 100m

So, the temperature at 200m will be 1.25 (100m) + 1.25 (100m) = 2.50

Therefore, the temperature at 15 + 2.5 = 17.5

Type 2 – Ambient Temperature

Q2) In tropical region an aircraft is flying at an altitude of 10 km. At that altitude, the temperature is – 40 °C. What is the ambient temperature on the ground?

(A) 24 °C

(B) 40 °C

(C) 30 °C

(D) 20 °C

Answer: (A) 24 °C

Temperature at an altitude of 10 km is – 40 °C

Environmental lapse rate is 6.5/km

So, the ELR is 6.5 x 10 = 65

Temperature at ground = 65 - 40 = 25

Type 3 – Virtual Temperature

Q3) A moist air parcel at 24 °C has a mixing ratio of 10g/kg. Its virtual temperature is:

(1) 25.81 °C

(2) 20.68 °C

(3) 31.25 °C

(4) 28.12 °C

Answer: 25.81 °C

Where,

Tv = Virtual Temperature

T – temperature

Mr – Mixing Ratio

So,

T = 24 °C + 10/6

T = 24 + 1.66

T = 25.66

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