On the Windbreak in the Field in Atsumi Peninsula

Abstract

A study was made for the purpose of preventing the injuries of the strong seasonal wind in Atsumi Peninsula. This locality is marked by complicated masses of hills, which render remarkable topographical effects to the wind direction and its force. And so suitable windbreaks for protecting fields are desirable according to the lay of lands. The study consisted of the following three parts: 1) Investigations of the relation between the wind and the lay of land; 2) Indoor experiments by means of model windbreaks and hills set in the stream of air from an electric fan; and 3) Examination of the influences of the actual windbreaks set on the hills. Resuls obtained are summarised as follows: Wind velocity increased at the top and end of a hill and was reduced in front and back of it. Wind directions, at a certain distance from the base of a hill, are the same as those of the mean flow. In the narrower vicinity of a hill, however. those are diversified by the influence of the undulatory topography. Above-mentioned relation was proved true in the indoor experiment, too, by which the effect of windbreaks at various points were investigated. Windbreaks (Ws) located near the top or the end of a model hill were found most effective, the best places for them being confined within a narrow bound, and the calming effect was reduced when it was located apart from those points (see Fig. 2). The windbreaks set near the top or the end of a hill could seperate easily the stream line of wind from the ground surface and performed a large calm region on the leeward, while by those at other locations such an effect was very small. And the results of the outdoor experiments showed that this fact might be applied also under natural conditions.