The experiments of prevention against frost damage by “heavy-oil-burning” in apple orchard were carried out at Suzaka in Nagano Prefecture at the nights of 20-21 April, 13-14 May, 1955. The area of experimental field was about 36×33sq. meters and oil-burning was continued from 3:02 a.m. to 5:00 a.m. on 14 May, 1955.
The results obtained are as follows:
1) Before burning the inversion level was formed at the height of 2m.
2) During burning the inversion level rose to the height of 2.5m, approximately, and the temperature rise was 3.9°C in the layer below the inversion level in 1 hour after firing, 1.5°C at the inversion level in 1.5 hour after firing and 2.4°C in the layer above inversion level in 13/4 hour after firing.
3) The maximum value on the horizontal distribution curve of temperature was 3.5°C at the height of 1.5m. at the center of the field, in 1 hour after firing. The warm air region was transferred from the west part to the center of the field and then returned westward conversely.
