Section 4C: Wind Flashcards
Briefly explain the terms (i). Isobars (ii). Pressure Gradient and Pressure Gradient Force.
List the factors on which the ‘angle of in-draft’.
State what effect each one of these factors have.depends.
Briefly explain the term ‘Coriolis Force’, covering the following: (i) What causes it? (ii) How it acts?
What is geostrophic wind? What factors do you use to estimate wind speed over land and over sea once you have measured the geostrophic wind?
Differentiate between: (i). sea waves and swell (ii). gust and squall (iii). veering and backing
State the ‘Buy’s Ballot Law’ and the cautions when applying it.
With the aid of sketches differentiate between the following: (i). Land and sea breezes (ii). Katabatic and Anabatic winds
Briefly explain the formation and the seasons of the (i). SW Monsoons (ii). NE Monsoons, in the waters of the S/SE Asian region.
List the precautions you would take when using Beaufort Wind scale to ensure accuracy of your estimations.
On a vessel steaming 346° at 15 knots, the apparent wind was observed to be NW at 22 knots. Find the direction and speed of the true wind. (Answer 273° at 12 knots)
From a vessel on a course of 243° at 12 knots, the apparent wind was observed to be 120° at 15 knots. Find the direction and speed of the true wind. (Answer 095° at 23.8 knots)
On the monkey island of a ship doing 117° at 16 knots, the anemometer and wind vane showed 15 knots and 036°. Find the direction and speed of wind required to be mentioned in the weather report. (Answer 345° at 20 knots)
Course 308° speed 14.5 knots. Direction of wind by observing of waves is NNE. Speed of wind by ship-borne anemometer-18 knots. State what direction and speed of wind is to be entered in the log book. State also, the direction towards which the funnel smoke will blow. (Answer NNE-7.5 knots [force 3]. Funnel smoke will blow towards 151.5°).
