Abstract:
The technique of inverse temperature of sloping fields as an effective method to prevent the frozen loss is applied to protect these fruit trees in practice. Comparison of results from the traditional methods which are laborious and costly in protecting fruit trees shows that the maximal increasing temperature effect of inverse temperature of sloping fields is excellent. By analyzing the characters of inverse temperature of sloping fields, to select appropriate regions for planting these fruit trees is significant in avoiding or mitigating the freezing harm to them. According to the investigation statistics data of low temperature of 2004 and 2005 in Lianjiang, the effect of low temperatures in sloping fields is studied. The results reveal that the temperature gap (Δ
td), which denotes difference between the low temperature of observation spot in sunlight days (
td) and the temperature at the bottom of sloping fields, is increasing with the increase of altitude where the hills with relative total altitude gaps (Δ
H) are 49 m. Along with the distance close to the top of the sloping fields, Δ
td and
td are larger and larger. Furthermore,
td is the highest, and the inverse temperature is prominent where the middle or upper parts of the hills with Δ
H are 100 m and relative altitudes ratios, which is the ratio (
G) between the relative altitudes gaps of observation spot and Δ
H are 0.90 approximately. As a result, based on the investigation in the study, a conclusion can be drawn that the inverse temperature of sloping fields has three characters as follows: in unclouded nights, the inverse temperature phenomenon that the temperature at the top or middle of the sloping fields is higher than at the bottom of the sloping fields exists at the hills. If Δ
H≤60 m, the formula can be acquired: Δ
td=
b0+
b1×
G (
b1 > 0), which means
td at the top of the sloping fields is the highest, and the maximum of inverse temperature (Δ
Td) can be calculated from the formula: Δ
Td=
b0+
b1. Else if 300 m > Δ
H≥80 m, they reveal that Δ
td can be calculated from the formula: Δ
Td=
b0-
b1×(
G-
b2)
2 (
b1 > 0,
b2 > 0), when
G equals
b2,
td is the highest and Δ
Td equals
b0; considering the hills where the relative altitude gaps are less than 300 m, the location of the ratio (
G) where the maximum inverse temperature exists is opposite to Δ
H, and with the increase of Δ
H,
G is descending; Δ
Td is correlated with the amount of push-join (
B) (which denotes the ratio between the azimuth of the push-join and 360°) and Δ
H of hills. When the
B are identical, with the increase of Δ
H, Δ
Td is increasing acco rdingly. When Δ
H are identical, because of the restrictive condition 1≥
B > 0, with the decrease of
B, Δ
Td is increasing contrarily.