December 7th, 2016

Tea Break Talk – Weather Systems

Posted in Article


Tea Break Talk – Weather Systems

Weather is probably the single most important factor to consider when planning a trip on the water – it will affect virtually every aspect of your journey, even down to whether you go or not! Therefore, understanding weather is very important.

Weather is a highly complex, not to mention fickle, phenomenon. We have put together below the basics on understanding weather systems to get you started.

Weather Sources
Global weather in general, comes from unequal heating of masses of air at the earth’s surface in places called source regions. Good source regions are the snow-covered polar plains and tropical and subtropical oceans. Therefore, an air mass might be cold and dry, cold and moist, warm and dry or warm and moist. As the air moves, the planet rotates underneath it.

Air pressure is essentially the weight of all the air above pressing down. It is dependent on the density of the air and the temperature of the air in the exact column above.

A high-pressure system, or “high,” is an area where the atmospheric pressure is greater than that of the surrounding area.

A low pressure system, or “low,” is an area where the atmospheric pressure is lower than that of the area surrounding it.

Humidity and Moisture
Air holds water vapour in suspension. The amount of water it can hold depends on the temperature of the air and the pressure. When the pressure is lowered by air rising, the air cannot hold as much water vapour and thus the water comes out of suspension.

The term ‘front’ denotes the clashing of two opposing air masses. All fronts are linked with low pressure systems. It is important to understand these as they generate significant changes in weather – sometimes fast.

Cold Front
A moving cold mass of air clashing into a stationary warm mass of air creates a “cold front”. A cold front will bring a drop in temperature and short, sharp showers.

Warm Front
A moving mass of warm air clashing into a colder mass of air will spawn a warm front. You will find fog and drizzle before a warm front and heavy rain as the front passes.

Occluded Front
Occluded fronts are linked with areas of low pressure called depressions. When a depression forms, there is usually a warm front and a faster moving cold front. An occluded front is formed when a cold front catches up with a slower moving warm front. Occluded fronts can generate quite stormy weather as they pass over.

Meteorology is the science of weather, and while forecasting weather is not yet an exact science, it is getting more and more reliable. Before going sailing, be sure to obtain the very latest weather conditions for your local area and prediction for the period you will be sailing.

If you have found this interesting and want to know more, why not sign up to an online sailing theory course. There is no reason why you shouldn’t start your sailing journey today!

Please look out for our next Tea Break Talk!

Happy sailing!