Recently, studies on the wind over cultivated fields have been put forward by Inoue and others, however, those on the air flow amongst the stalks have scarcely been carried out.
The author describes the result obtained primarily of the velocity of the horizontal airflow, intensity of turbulence and the scale of turbulon amongst the stalks in the paddy rice field of Mishima (Shizuoka Pref.) at August 29th, 1955.
Making use of the hot-wire anemometer (Platinum, diameter 0.04mm, length 50mm), the horizontal components of the air flow amongst the stalks at the height of 40, 55, 70, 85, 100cm are recorded for the averaging time of 90 seconds, and the results are analysed by reading in every 0.5 seconds.
The result are as follows:
1) The velocity of the air flow amongst the stalks at each height are shown to be from 12 to 22cm/sec, in spite of 220cm/sec at 200cm height as shown in Fig. 1 and Tab. 1.
2) The intensity of turbulence (<u'2>1/2/u) are nearly constant with height.
3) Tu (the passage time of the horizontal largest turbulon) were obtained at each height from Fig. 2, and the scale is calculated by ∧u=uTu……(1) The scale of the horizontal largest turbulon ∧u obtained from (1) is nearly constant with height as shown in Tab. 1, and the magnitude is of the order of about 1×102cm.
4) Roughness parameter z0 is estimated from the distribution of wind velocity measured by small-type Robinson anemometer at the most prosperous stage of tillering in paddy field, the ratio α(=h/z0) is found to be 0.39-0.42, which is to be in comparison with 0.35-0.39, reported previously at same stage, where is the height of rice plants.
