Observations and Considerations on the Structure of the Down Slope Wind

Abstract

The following is the summary of the result of the observation on the down slope wind at Hakatajima of the Inland Sea of Seto (at 39°4′ Lat.; 133°05′ E, Long.) from October to November in 1961.
(1) The down slope wind on clear and calm nights arises immediately after sunset and lasts till the sun rises next morning, so long as there is no special change. The wind velocity, in many cases, is one meter per second and the wind goes on blowing at an almost constant speed with little change all night long.
(2) The down slope wind in a small valley is 25-30 meters thick, and the air temperature falls till about 4°C and the maximum wind velocity is generally found in the five meters' layer.
(3) The down solpe wind both on the ridge of the side of the valley and in the upper part of the valley is weaker in the strength and more irregular than that in a valley, but it has the characteristics of the down slope wind and blows down along the slope, Its thickness is not fixed.
(4) The observed down slope wind coincides with PRANDTL's theory either for the vertical distribution or maximum wind velocity, but the observed air temperature distribution does not coincide with it. The discrepancy may be explained by the fact that, though the theroy treats the two-dimensional phenomenon, it is three-dimensional in the actual cases.