# Environmental Science: Numerical Questions – Geostrophic Wind

Dr. Manishika Jain- Join online Paper 1 intensive course. Includes tests and expected questions.

Air Geostrophic Wind: Numerical Questions | Environmental Science

## Geostrophic Winds

Q1) At a latitude of 30°, there is pressure gradient of 5.0 mb per 100 km. Given the density of air ⁓1.25 kg/m3, the geostrophic winds will have velocity (m/s):

(1) 5.48 m/s

(2) 54.86 m/s

(3) 109.72 m/s

(4) 27.43 m/s

Answer: Option (2) 54.86 m/s

Given Values are,

Latitude = 30° (Sin 30° = 0.5)

Pressure = 5 mb (5mb*100 = 500 Pa)

Density of Air = 1.25 kg/m3

Distance = 100 km (100 km *1000 = 100000 m)

Vg =

Where,

Vg = Geostrophic wind Velocity

P = Pressure (in Pascal)

𝛀 = Angular Velocity of Earth (7.3*10-5)

δ = Density of Air

Sin ɸ = Latitude

D = Distance (in meters)

Now putting the given values in the equation,

Vg =

Vg =

Vg = 54.79 m/s

Q3) If at latitude φ = 30°, pressure gradient is 15 mb per 1000 km, the geostrophic wind velocity will be:

(1) ~ 20.54 m/s

(2) ~ 15.92 m/s

(3) ~ 7.96 m/s

(4) ~ 10.27 m/s

Answer: Option (2) ~ 15.92 m/s

Given Values are,

Latitude = 30° (Sin 30° = 0.5)

Pressure = 15 mb (15mb*100 = 1500 Pa)

Density of Air = 1.25 kg/m3

Distance = 1000 km (1000 km *1000 = 1000000 m)

Vg =

Vg =

Vg =

Vg =

Vg = 16.43m/s