Grade 10 – Nautical Science

December 14, 2020

Wind

Vertical and horizontal movement. Wind can be defined as the movement of air from a high pressure to a low pressure area. Consider two columns of air AB and CD. They are of equal cross sectional area, height and temperature and the pressure at A and C are equal and […]
December 14, 2020

Atmospheric pressure, depressions and anti-cyclones

Atmospheric pressure and temperature are mainly responsible for our weather systems. Atmospheric pressure is the pressure that the air exerts on the surface of the earth and everything on it. It changes with altitude and temperature. The air pressure in Johannesburg is less than that at the coast. When the […]
December 14, 2020

Air masses and fronts

Air masses are large areas of air having the same characteristics throughout. They may be either warm or cold, depending on whether their source is polar or tropical. They are also classified as either maritime or continental. When two different air masses meet they form a boundary which is known […]
December 15, 2020

Communications – introduction

Introduction. Communication plays a very important part in modern society. We have advanced from the days of the old land-line based telephone and postal (snail) mail to mobile phones and e-mail. Technology has given us the ability to communicate with each other instantly and anywhere in the world. It has […]
December 15, 2020

Flags

The use of signal flags goes back a long way and was made famous by Nelson shortly before the battle of Trafalgar. Although not so extensively used today, flags as a limited means of communication has managed to survive. The merchant navy make use of a total of 40 individual […]