Micro-meteorological characteristics in the vineyard (1)

Abstract

This paper includes several results of investigation which, the authors hope, would provide some data to both the micro-meteorological problems of the grape culture and the relation between the micro-meteorological characteristics and the density of crops.The micro-climate in a vineyard in Kofu, which is the chief producing district of grapes in Japan, was investigated for several days in both summer and autumn, i.e., June 21-22, and October 11-13, 1952.It was found that in the vineyard there were two layers of thermal importance, i.e. the soil surface and the trellis of grapes, and that the trellis had more and more strong influences on the micro-meteorological characteristics in the vineyard with the increase in the degree of its luxuriancy.Typical vertical distributions of temperature in the vineyard are shown in Fig. 1, where a maximum temperature in the day time and a minimum in the night are both found at the upper surace of trellis.The air temperature under the trellis in the vineyard was distinctly lower than that at the same level in the open land in the day time, and, reversely, in the night the former was slightly higher than the latter. These phenomena seem to be due to the fact that the trellis protects the outgoing radiation from the underlying soil surface.This tendency became more and more remarkable with the degree of luxuriancy of the trellis as shown in Table 4.The relative humidity distributions near the trellis are shown in Table 2. It was recognized that the humidity in the day time was the highest at the middle part of trellis and the lowest at the upper part, and that under the trellis it increased with the degree of luxuriancy of trellis as shown in Table 5. In the night, however, there was no difference between them.In this survey, it must be noted that the vertical distribution of air temperature near the ground in the night was of the same type as what was advanced by L. A. Ramdas and the others (1932), but disagreed with what has been called “Nocturnal outgoing radiation type” by R. Geiger (1927) up to this time.