SO₂の植物への収着の機構とSO₂に対する植物の抵抗性との関係を明らかにするために, 葉面の各部位により異なる可視障害発現を取りあげ, 制御された環境下で実験を行い, 解析した。得られた結果は次の様に要約される。
(1) SO₂暴露に伴う植物の被害発現に至るまでのQ/w′とP_asとの間には, Q/w′≅1.8×10^-3P_asの関係が成立する。これは, モデルQ/w′=(k_w/k_sk_r)(P_as-P_ls) においてk_r=1.53, P_ls=0 vol ppmとして計算した値と一致する。
(2) 光, 温湿度, 風速等を一定に保った実験装置内で, SO₂暴露下における葉気温差ΔTと蒸散速度Wとの間に線形関係が成立した。そして, その回帰係数は, -5.8×10⁵cm²s・℃/gであった。(1)で得られた関係と合わせて考えると葉温を測定することにより, 蒸散速度すなわち気孔開閉の程度が推定され, 更にSO₂収着速度を推定することができる。
(3) SO₂暴露下において, 葉面の各部位における可視障害発現の程度とその部位における葉温の変化との間に密接な関係が認められた。すなわち, 葉温の上昇が遅い部位程, 被害の程度が大きくなる傾向があった。これは, 葉温上昇が遅い部位程気孔の閉じる速度が遅く, 葉温上昇が早い部位に比べてより多くのSO₂を収着するためと考えられる。

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The transpiration rate of cucumber leaves was measured with a potometer to know the values of diffusive resistances of the boundary layer and stomata. The transpiration rate oscillated with about a 30 minute period under constant environmental conditions and its amplitude increased with saturation deficit, wind speed and light intensity. The oscillation was caused by a delay in stomatal response to changes in leaf water content.
An increase in wind speed resulted in an increase in transpiration rate, but the rate decreased gradually with wind speed above 100cms^-1 under the conditions of large difference in water vapour pressure between leaf and air and of high light intensity.
Dependence of the diffusive resistance to water vapour on wind speed was shown for three values of light intensity. Decrease in the boundary layer resistance was observed with increasing wind speed. The effect of wind speed was particularly dominant for wind speeds below 60cms^-1. Decrease in stomatal resistance was revealed with increasing light intensity. Under a rather high light intensity of 0.75calcm^-2min^-1, the stomatal resistance, however, increased with wind speed higher than about 60cms^-1.

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The purpose of this paper is to show relationships among several hailfall parameters and degree of crop damage to those concerned about hail hazards in Japan. There are a few papers discussing this subject in Japan, but in those were used hail data obtained by interviews and questionaries from people living within and around hail damage areas. Such data are generally very inaccurate and not infrequently unbelievable values are reported as truly occurred. Even now physically unsound theories using unrealistic scales have been adopted even in an authorized handbook as a guide to hailfall characteristics vs. crop injury relationships. On account of establishment of hail observation network by the National Research Center for Disaster Prevention (NRCDP), and later increase of number of stations operated by local governments, it has become possible to obtain more accurate data in a portion of northwestern Kanto district where damaging hailstorm hit relatively frequently. However, the instruments used there are so called hail pads, the simplest kind hail-recorder.
The parameters examined in this paper are the maximum hailstone diameter d_max, number of hailstones N (for all sizes) and N* (for d>6.4mm) per unit area, amount of hail per unit area M, impact energy per unit area E_I, and percent crop damage D. We deduced hailstone diameters from dent diameters on aluminum foils. Discrete values are obtained. The value 6.4mm which happened to be equal to 0.25 inches is one of such a value. The percent crop damage is determined just after the hailstorm, and the values are quite rough. Although there were various kinds of crops in the area under consideration, the values of D refer to wheats which were just before harvest. The case studied here occurred on 9 June 1975. On this day damaging hail occurred at many places scattered over the wide area in northern and eastern Honshu, the main island of Japan. Gunma prefecture experienced the most extensive damaging hail ever known. About a dozen of hailclouds were identified by the NRCDP's radar situated at Fujioka in the southern part of this prefecture. Detailed study of the hailstorm were made by the authors (Omoto, Yagi, and Seino, 1976). The damaging hail discussed in this paper was brought by one of a quasi-supercell type convective system. It formed near the southwestern edge of bandshaped multicellular intense convective system, but unlike to other previously formed cells this one moved more or less independent of the main echo. The storm accompanied extraordinary intense rain (20-30mm in 5 minutes or less) as well as severe hail and strong gusts. There appears to be a quasi-periodic change in the intensity of the storm as revealed by the distributions of various hailfall parameters (Fig. 8). However, no corresponding change was identified from the radar data.
Following statements are made as the summary of this preliminary study. (1) Degrees of crop injuries are relatively well correlated with following hailfall parameters: a) impact energy per unit area E_I, b) the amount of hail per unit area M, c) the number of hailstones equal or larger than 6.4mm. (2) Total number of hailstones per unit area N, and maximum hailstone diameter d_max are less correlated with crop injuries compared with those given above. (3) Damage intensity is roughly proportional to Log E_I and N* for 30≤D≤95% (note: Fig. 10 showing this relationship is more or less illustrative and not given for practical use). (4) Hailstones smaller than 6.4mm in diameter give weak or no damage to crops unless the amount is extraordinarily great. (5) Duration of hailfall in the area was very short, i.e., even in severely damaged area it was less than 5 minutes.
(6) Hailfall amounts converted to rainwater were relatively small. Even in an area with severe

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人為的な湖の形成 (ダム等) や消滅 (干拓等) が周辺の自然や農業に及ぼしている影響を質的に量的に把握することを目的として湖周辺の局地気候に関する研究を開始した。今回観測を行なった洞爺湖は直径が約10km, 周長46kmの円形に近いカルデラ湖である。観測は1977年1月20・21日に行なった。自動車の屋根にとりつけた直径0.3mmの銅・コンスタンタン熱電対により気温を測定し, ペンレコーダーに記録しながら湖岸にそって周回した。得られた結果を要約すると次のごとくとなる。
(1) 観測期間中の水温は1～5℃であったのに対し, 気温は最高約-2℃, 最低-15℃で水温-気温差は最大10℃であった。
(2) 湖周辺の風向は昼間には一般風の影響をうけていたが夜間には周辺から湖に向って風が吹き込んでいた。
(3) 湖周辺の気温は一般風の影響の強い昼間には湖の風下では風上に比べ約2℃高温であった。
(4) 夜間の気温分布は昼間に比べ場所による変動が大きく地域により約5℃の差があった。

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Four formulae for estimating the greenhouse heating degree-hour have been presented so far by three authors in this country. Every one is expressed as a function of only the difference between an inside temperature desired and the daily minimum outdoor temperature without any consideration for sunshine; two of them indeed exclude daytime from calculating the degree-hour.
In this paper, the daily mean of bright sunshine hours (S) is introduced into equations for daily degree-hour (DH) which are based on four factors; desired inside temperature (T_C), daily maximum temperature (T_H), daily mean temperature (T_M) and minimum temperature (T_L). For T_C≥T_H,
DH=24(T_C-T_M)-S(T_C-T_H+T_M/2)
and for T_C<T_H,
DH=24(T_H-T_M)(T_C-T_L/T_H-T_L)²-S/2(T_C-T_M)²/T_H-T_M
These formulae were derived on the assumptions that bright sunshine renders greenhouse heating unnecessary even when the outside temperature is lower than T_C and that the diurnal course of the monthly averaged outdoor temperature can be approximated by two straight lines connecting T_H and T_L.

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Using a water channel and the flow visualization technique (hydrogen-bubble visual observation method), we investigated the structure and flow patterns of the boundary layer near leaves. We discussed the mass transfer through the boundary layer, which plays an important role on photosynthesis, by use of the experimental results.
The shape of the boundary layer of a leaf was not flat film, but that was of the three dimensional shape which enveloped a leaf. Increasing the velocity and/or the incidence of flow on leaf, the boundary layer became turbulent, and the sectional form of that became convex on account of the edge effect at the side tip.
It was observed that under fluttering condition, the transition from laminar to turbulent flow was not promoted by fluttering of leaf alone and that the structure of the boundary layer was found to be turbulent or laminar according to the conditions of flow and flutter.
Generally, mass and heat transfer through the boundary layer is analyzed by using a laminar boundary layer theory, but the mass transfer estimated by our experimental results differs in following respects from that by the boundary layer theory.
1. Under the flow condition parallel to the leaf, the boundary layer at the side tip becomes thin, and the estimated amount of mass transfer seems to be slightly more than that of the calculated value by the theory.
2. When the incidence is 7-14°, the boundary layer on the lower surface becomes thin, and the boundary layer on the upper surface is converted into turbulent structure. The estimated amount of mass transfer becomes more than the above case 1.
3. In the case of larger incidence, the resistance to diffusion at the upper surface increases as the dead water region expands. The estimated value of mass transfer is nearly equal to case 1. The feature of the boundary layer on the lower surface is the same as case 2.
4. In the case that the leaf flutters, the resistance decreases when the boundary layer is turbulent. The estimated value of mass transfer is by about 60% larger than the theoretical value, but it is by only 10% larger than the theoretical value when the boundary layer is laminar.
It is found that the mass and heat transfer through the boundary layer can not be dealt with without the understanding of the features of boundary layers.

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