Swaying of trees as caused by wind: analysis of field measurements.

• Main Authors: Peltola, Heli, Aho, Jorma, Hassinen, Alpo, Kellomäki, Seppo, Lemettinen, Matti
• Format: Article
• Language: English
• Published: Finnish Society of Forest Science 1993-01-01
• Series: Silva Fennica
• Online Access: https://www.silvafennica.fi/article/5505

Measurements of wind and subsequent swaying of two Scots pines ( L.) were made at stand edge conditions. The horizontal windspeed was measured ten meters outside of the stand edge for four heights using cup anemometers. The compass directions were determined using a directional vane placed above the canopy. Tree swaying was measured by accelerometers at xy-coordinates. The shape of the wind profile at the stand edge varied to some degree depending on windspeed, but the form was a logarithmic one. Swaying of trees increased along with increasing windspeed. Furthermore, swaying was more or less irregular in relation to xy-coordinates, but it occurred, however, mainly perpendicularly to the direction of mean windspeed. The maximum bending of trees to the direction of mean windspeed varied also only little for various gusting windspeeds (average windspeed of 20 seconds) and dynamic wind loads. The maximum bending of trees was also in most cases less or equal to those predicted on the basis of static wind loads, when the mean windspeed for static load is taken as equal to the gusting windspeed.Pinus sylvestris