Abstract
In this report, structures of wind are evaluated from, data of observations carried out both on summer and in winter.
Several properties of turbulence are larger in summer than in winter in the air layer more than 10 meters high above the ground. Also, the relation between mean velocity and turbulence of wind is obtained. Velocity fluctuations and mixing length increase nearly proportionally to the increase of mean velocity, and eddy viscosity increases with square of mean value.
Phenomena of transition from laminar flow to turbulent flow are described. u'(fluctuation of velocity along mean flow) is always negatively correlated with T'(fluctuation of air temperature). It was assured that turbulence of air temperature is mainly due to the local convection on the clear and calm day, whereas turbulence of wind is almost due to the random movement of lumps of air (mixng motion).
