A diagram which permits the direct evaluation of heat units for any period of two dates or for any base temperature is designed and three examples for specified places of Japan are given. As is seen, the ordinate is the temperature or the number of days between two dates and the abscissa is the date of callendar, and equi-cumulative temperature lines in degree-days taking the 0°C as the base temperature are drawn. Of course, the same design will be applicable for the evaluation of other cumulative meteorological elements such as the duraion of sunshine and the amount of rainfall, etc.

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In this paper, the influence of structural conditions of a glasshouse and of meteorological conditions on the night fall of air temperature in the glasshouse was mainly investigated by employing a solution of response function of the air temperature in the house to cuter air temperature with a quadratic time change.
The time change of the inner air temperature (_iT_a) after the initial transient (t≥3.6×10³sec) was found to be
_iT_a(t)≅1/P{Q₀+(Q₁+2b)(1/P-t)}+bt².
where Q₀=PT₀+A_w/C_pρV_c(A_f/A_wB₀-h_tfF_H/₀h), Q₁=(aP-A_fα/C_pρV_c), P=A_w(h_f+h_ad)/C_pρV_c.
A_w and A_f are the wall area and the floor area, h_t and h_ad total heat transfer coefficient and ventilating heat transfer coefficient, V_c the volume of the glasshouse, oh the heat transfer coefficient at the outer surface of the wall, f the shape factor characterizing the heat loss by effective radiation, F_H the effective radiation measured on a horizontal plane, a and b constants in an empirical formulae for the night fall of air temperature outside the house, B₀ the soil heat flux at the time of sun set, and α the gradient of the time change of the soil heat flux. The above relation was used to calculate the difference (τ_t) in air temperature between in and out the glassouse, that is the lag of air temperature in the glasshouse(see Eq. 13).
The relationship between the shape factor (f) and the ratio of floor area to the wall area was studied on the basis of the equation for the effective radiation on a sloped surface. It was found out from model computation that the shape factor changes linearly with the ratio (A_f/A_w) as follows;
f=0.45+0.55A_f/A_w.
The next relation shows that the lag of air temperature (τ₁₂) at the time of sun up changes proportionally to the gradient (α) of the time change of soil heat flux (B_s′).
τ₁₂=4.2+0.8·10⁸α.
In the case that α is less than -5.25×10^-8, the values of the temperature lag become subsequently negative, indicating that the air temperature in the glasshouse is lower than that outside the house.
The lag (τ₁₂) of air temperature in the glasshouse increased in proportion to the ratio of the floor area to the wall area. The change in the lag of air temperature with the ratio (A_f/A_w) was more steep in the case of the glasshouse with smaller values of the total heat transfer coefficient than in the opposite case. The following relation shows the linear dependence of the degree hour upon the lag of air temperature at the time of sun up,
D.H.=12.7τ₁₂.
The lag (τ₁₂) of the air temperature in the glasshouse decreased throughout the range of ventilation values applied and the inner air temperature approximated gradually to that outside the glasshouse, although the initial decrease is more rapid. The heat loss from unit outer glass surface by effective radiation was found to be approximated by h_tfF_H/₀h.
The influence of effective radiation on the temperature environment in the glasshouse becomes remarkable with increasing the value of constant fh_t/₀h.

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In order to study the nocturnal cooling of plant communities, the fall of temperature of a wheat field during night was calculated for various values of net radiation and of wind speed above the surface of the wheat field, 60cm height and with 4.4 of L A I. The results of the calulation were compared with the fall of temperature of the bare soil surface during night.
As it is observed that the thermal condition of the plant layer is approximately in equilibrium for the time just before sunrise, the vertical distribution of leaf temperatue, air temperature and water vapour density within the plant layer at the time of sunrise are calculated with various values of net radiation and of wind speed at the height 40cm above the surface of the wheat field on the assumption of equilibrium condition.
The calculated profiles of leaf temperature and air temperature for 0.10cal·cm^-2·min^-1 of net radiation are shown in Fig. 4 for the values of 0.5m·sec^-1 and 3.0m·sec^-1 of wind speed. It is seen from Fig. 4 that difference between the temperatues of the upper part of plant layer and of soil surface under the plant layer is about 9.0°C for 0.5m·sec^-1 of wind speed and about 0.5°C for 3.0m·sec^-1.
The fall of temperature during night was obtained from the difference between the calculated value of temperature and the temperature at the time of sunset. The temperature at the time of sunset was assumed to be equal to that at the top of the inversion layers. The fall of leaf temperature of the upper part of the wheat field, shown in Fig. 3, is in very close agreement with observational values. As seen in Fig. 3, the temperature fall increases rapidly with decreasing the wind speed below 1m/sec.
The fall of temperature of the bare soil surface was also calculated for the radiation values and the wind speed at the height 50cm above the soil surface. The calculated results of the fall are in good agreement with those of BERLYAND (1956). The variation in the fall of temperature of the bare soil surface with wind speed is not so apparent as in the case of the wheat field.
By use of both calculated results of the wheat field and of the bare soil surface, comparison was made of the fall of temperature of the upper part of the wheat field and of the bare soil surface under the same meteorological conditions. From the results it can be inferred that the night minimum temperature of the upper part of the wheat field is lower than that of the bare soil surface for the condition of calm wind, but that for windy condition the reverse is the case.

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The relation between the temperatures in and outside the vinylhouse and the soil surface temperature in the house has been analysed by equivalent electric circuit. As the impedance has only the resistance, the simple relation has been found. Three points are remarked about the vinyl house of the Saitama-ken Hort. Exp. Stat.
(1) The temperature outside the house becomes less effective on the vinyl house temperature with coverings.
(2) In the doubly covered house, the soil surface temperature affects more effectively on the air temperature. The effect is a little accelerated by curtaining.
(3) The effect of the soil surface temperature on the air temperature in the house is almost exclusively determined by curtaining. The effect becomes less in the double-covered house.
When the soil surface temperature is analysed by the use of the layers of the invariable soil temperature, the relation becomes complicated by the entry of the equivalent electric capacity.

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In a previous report, the author indicates that wet cooling power is more suitable than disconfort index of sultriness. Pattern of the diurnal course in wet cooling power changes with places. Particulary the time of the minimum largely different with each place. It is more desirable to use the daily mean of wet cooling power instead of that at the specified time in climatological study of the sultriness. The normal of monthly mean wet cooling power in summer season is calculated in Japan. It is found that the sutlriness is more mild in the district with wind speed higher than 3.0m/sec, while the sultriness is very unbearable in the district with wind speed lower than 2.5m/sec. Tha daily mean of wet cooling power at Takamatsu is calculated for summer season and used to study the climatology of sultriness in this district.

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