Although not every boat trying to circumnavigate Vancouver Island will be a sailboat, all skippers and crew should be aware of the current weather, particularly winds. The winds will determine the waves, sometimes the currents you are facing, and often the visibility where you’re at, and they can help or hinder you on your voyage.
Wind jargon
There is a lot of jargon relating to wind. Jargon, at its simplest usage, is very precise terms to describe something which is relevant to a particular task. Cruisers must be able to use and understand wind jargon.
Wind and land
The interaction between moving air and topography has many outcomes, but here are some terms and the usual effects they describe:
- corner wind
- Increased wind speed as a wind blows past a headland, generally parallel with shore. Such winds may be dramatically higher than winds reported from either side of that headland.
- funnel wind or gap wind
- Increased wind speed caused by a narrowing or channeling of the wind, usually to a larger basin beyond.
- land breeze
- A night breeze blowing from land to sea, caused by the rapid cooling of air over land being drawn by the rising, warmer air over the adjacent waters.
- lee effect
- Turbulence and eddying produced to the lee of a topological object. Below a cliff, for example, the offshore wind may be variable gusty, possibly even the opposite direction of the wind at the top of the cliff.
- sea breeze
- A day breeze blowing from sea to land, caused by rapid warming of air over land drawing the relatively cooler air from over the adjacent waters.
- upslope wind or anabatic wind
- A day breeze in valleys and inlets caused by warming of uplands; generally a larger-scale but focused sea breeze. See also williwaw
- williwaw or katabatic wind
- A night wind caused by sinking cooled air from uplands, often stronger than an upslope wind and may be violently gusty. Generally a larger-scale but focused land breeze.
Named winds
On the coast of British Columbia there are a number of regional climate features which result in distinctive wind patterns that repeat often enough to have been ‘named.’
- Qualicums
- A strong westerly wind funneled through Barkley Sound past Port Alberni and dropping down into the Georgia Basin over Qualicum Beach. Known for creating rough seas in the vicinity of Texada Island.
- Squamish
- Heavy, cold air mass forming inland which suddenly spills down mainland inlets as strong, gusty winds. Due to their unpredictability, these can be sudden and dangerous, and is why any unexpected channeled breeze may be described as a ‘Squamish’.
Wind and weather
Wind is air moving from an area of higher general pressure toward an area of lower general pressure.
- gradient
- Shortened from ‘pressure gradient’; the continuum of relative atmospheric pressure between two locations, most usually referring to a high and a low pressure centers. The steepness of the gradient is based on the difference between the two pressures and the distance between them. A ’sharp’ or ’steep’ gradient has a rapid change over a short distance, while a ’shallow’ or ‘mild’ gradient has small pressure change over a short distance. The sharper or steeper the gradient, the greater strength of the associated wind.
- wind rotation
- The rotational (or corriolis) movement of winds to or from an atmospheric pressure center. In the northern hemisphere winds flow clockwise around a high pressure cell, and anti-clockwise around a low pressure cell. The reverse is true in the southern hemisphere.
- Wind moves from a high pressure system toward a low pressure system, but due to the wind rotation it doesn’t move in a straight line. In the northern hemisphere, with the wind behind you, the low pressure system is to your left, and the high pressure system is to your right.
