Waec Model Questions Vol1 2019 Geography Question 4

Three weather stations (S1, S2 and S3) are situated on a straight line running east‑west across a region. Their coordinates and observed sea‑level pressures are given below: - S1: 5 km east of the western end, pressure = 1012 hPa - S2: 55 km east of the western end, pressure = 1008 hPa - S3: 105 km east of the western end, pressure = 1010 hPa Assume the stations are equally spaced in the east‑west direction (i.e., the distance between successive stations is 50 km). Using the data, answer the following: (a) Plot the pressure values on a simple sketch map (distance axis only) and label the points. (b) Identify the approximate position of the centre of the low‑pressure system. (c) State the direction of the pressure‑gradient force acting at station S2. (d) Estimate the geostrophic wind speed at S2 using the formula V = (1/ρf) × (Δp/Δd), where air density ρ = 1.2 kg·m⁻³, Coriolis parameter f = 1.0 × 10⁻⁴ s⁻¹, and Δp/Δd is the pressure change per unit distance between S1 and S3. (e) List two possible sources of error in the wind‑speed estimate obtained in part (d).