December 14, 2020

Meteorology (weather at sea) – sources of meteorological information

Sources of meteorological information available to the mariner include the following: Maritime coastal radio stations (Walvis Bay, Luderitz, Cape Town, Port Elizabeth, East London, Durban). These provide storm warnings and weather forecasts. Cape Naval Radio (Silvermine, Cape Town). They provide facsimile weather maps and weather forecasts on behalf of the […]
December 14, 2020

Meteorological instruments

The met instruments usually carried aboard merchant vessels and warships are the following: Barometer. This instrument measures the atmospheric pressure (usually in millibars). They can either be mercury barometers or aneroid barometers. The first type uses a column of mercury to measure to measure the pressure, whilst the aneroid uses […]
December 14, 2020

The atmosphere

The atmosphere is divided up into a number of layers as follows: The Troposphere. This layer stretches from the surface of the earth up to 18 kilometers above the earth. Most of the weather changes occur in this layer. Stratosphere. This layer stretches from 18 to 32 kilometers above the […]
December 14, 2020

Weather signs at sea – humidity

The amount of water vapour in the air varies from place to place and from time to time, and is an important factor in determining the nature of the weather. The amount of water vapour that the air can hold in an invisible state is limited and varies with the […]
December 14, 2020

Cloud formation

Clouds are formed when warm, moist air rises until it reaches the air’s saturation point (dew point). After this the moisture in the air condenses into visible droplets and clouds are formed. There are two basic types of cloud. Cumulus clouds. When air is heated by the surface of the […]