Website of the Friends of the Jersey Maritime Museum

Association of Jersey Charities Number: 167

Maritime Jersey

fomm compass (sm) FJMM flagpole

Object of the Month

Every month an object from the collection will be featured here:

February 2013

 

Weather vane, 1997

This weather vane has been made by sculptor Mike Woods.

 

The top of the weather vane is decorated with a chasse-marée and the vane itself is a wave-like structure. A shaft leads down from the vane on the roof into the building and is connected to an indicator. This is simply an arrow, superimposed on a map of the island.

Mike Woods, artist

 

We are interested in two components of the wind: direction and speed. Direction can be measured simply by a pennant on a pole or by a wind vane. The most common wind direction in Jersey is west to northwest and northeast to east. The stongest wind during the Great Storm of 1987 was from the south which was most unusual. Jersey is more windy than inland areas in Britain or France because the effect of the wind moving over the land - friction from obstacles - slows down the wind speed.

 

The first instrument to measure wind speed was a cup anemometer, invented in 1846, consisting of three hemispherical cups which revolve, the faster the wind speed the faster they revolve. Wind speed varies with height so there is a standard - all weather stations report the wind at ten metres above in a well-exposed location.

 

The mean wind speed in Jersey is twelve knots, about Force 4 on the Beaufort Scale.

Frank Le Blancq, Senior Meteorologist

weathervane1997

The  Beaufort scale was devised in 1805 in a time of sailing ships and the Napoleonic Wars. It consisted of three things - a number between 0 -12, a name such as calm or hurricane, and a description of the behaviour of a man-of-war in the wind strength. Over the years it’s been modified to describe the state of the waves and the effect of the wind on the land, with which it is easier for landlubbers to relate.