Abstract
It is a well-known fact that during the cold season the diurnal change in the velocity of westerly winds is often experienced especially in Kwanto distrlct afer the passage of a developing cyclone to the east of Japan proper. As a result of investigation, the cause of this phenomena was found to due to the striking contrast in the amplitude of daily temperature waves in Kwanto plain and the central plateu district. In the daytime, owing to the excessive rise of the air temperature in Kwanto district, the cold and heavy air flows sweeping over our district as descening current being unable to keep the stable equilibrium, but at night the case is opposite. Combining this periodic flow of air with the steady gradient winds which come from the west, then the resultant winds develop strongly in the daytime while they fall calm in night-time.
