Wind

The wind has a great influence on our everyday life, particularly when we have strong winds caused by low pressure systems.

The wind has historically always been important. Without wind it wouldn’t have been possible to sail ships across the oceans. Despite the transition to motorized vessels it still plays a significant role in the commercial shipping industry. Aviation also uses strong winds, jet streams, high up in the atmosphere in order to save fuel, especially on longer trips.

The use for wind as a commercial interest has increased. The interest and market for wind power as an energy source has expanded exponentially over the past decade in Sweden and many other countries around the world.

Wind is an important aspect when designing and constructing buildings and bridges etc., because structures must be able to handle strong winds. The wind's destructive power is also of great importance for Swedish forestry, where severe storms in the past have had devastating effects on different parts of the country's forests.

Sea levels along our coasts are affected by the wind. When the wind blows toward the coast, it pushes water towards land and thereby raises the water levels on the coast. On the other hand it can lower the sea level along the current coastline if the wind blows from land and out to sea. This mainly affects Swedish coastal cities in terms of planning the location for existing and future buildings.

Wind climate historically

How has the wind varied in Sweden?
Have there been any changes?
Are there any trends?

A few years ago SMHI analysed how the wind climate in Sweden has varied historically. In the absence of long homogeneous series of wind speed measurements in Sweden, air pressure observations from a number of weather stations around the country were used. The stations were grouped in threes so that they formed a triangle. The southernmost triangle was the Gothenburg-Visby-Lund. Based on observations from these sites the researchers could calculate the so-called geostrophic wind, which is a type of idealised average wind speed between observation points.

The geostrophic wind has been calculated for nine triangles over Sweden. For the two southernmost triangles the analysis could use data from 1901 and for the remaining seven triangles from 1951. Various features of the geostrophic wind have been calculated for each of the triangles; each year's highest wind speed, the yearly average wind speed, potential wind energy and number of events during the year with wind speed of at least 25 metres/second.

Results from this analysis showed no statistically significant trend in any of the above mentioned measurements of wind characteristics in the country as a whole. In northern Sweden, however, a decrease in the average wind speed was seen. There was an increase in the year's highest wind speed in five of the geographic regions and a decrease in the other six areas. The conclusion was that no trend could be verified for the country as a whole, even if the particular trend could be statistically significant in one triangle.

Storm damages in the future

Climate scenarios provide no clear answers on how the wind climate might change in the future, however there will be more or fewer storm-rich years or decades as in the current climate.

Milder winters with increased precipitation are expected to become more common in a future climate, and gradually the conditions for soil frost will change. As a result the risk of storm damages can increase regardless of changes in the wind climate.