Wind is normally not directly harmful to sea cage farms. The area of the farm above the water surface, where the wind blows, is small. On large operational platforms with buildings, however, the wind will have some effect.
Wind can be separated into two components: one normal and the other fluctuating (gusts). The amount of gusting depends on the local topography. It is normally gusts of wind that cause damage, for instance to houses. The wind velocity increases with height above the ground. For meteorological pur-poses, wind velocity is measured 10 m above the ground (V10). Because it varies continuously it is given as an average over a period, normally 10 min. Many meteorological stations measure the wind velocity; however, a large number are located at air-ports or lighthouses, where the landscape is quite flat with few mountains to create gusts. When transferring these wind data to other sites, this must be taken into consideration. An easy method to present the wind conditions on a site is by using wind roses; these show where the major wind is coming from and may also show the average strength of the wind from the various directions over a given period (Fig. 15.10).