关键词: 光照, 光照

Abstract:

Frost, snow and low-temperature disasters may occur throughout the year in Shanxi plateau, they have significant impacts on industrial and agricultural production, transportation and people’s lives, and even cause serious losses. In order to prevent and mitigate such disasters, it was needed to in-depth study their characteristics and regularity. Through collecting, reorganizing and analyzing the data about Shanxi from 1949 to 2000, the article studies the grade series, stage changes, different grades’ periodicity and reason of the frost, snow and low-temperature disasters. The statistical results showed that the disasters had 374 times, they might be divided into mild，moderate and severe disaster, and their occurrence probabilities were 16.8%, 61.0% and 22.2%. The disasters could be divided into 4 stages. The first stage was from 1949 to 1956, the second stage was from 1957 to 1975, the third stage was from 1976 to 1995 and the forth stage was from 1996 to 2000. The first and third stages were that the disasters happen frequently, and most of them were moderate and severe disasters. The second and forth stages were that the disasters happen occasionally, and most of them were mild and moderate disasters. According to wavelets analysis, it was known that there were mainly periods of 2-3 a, 5-8 a and 15-20 a. The main reason causing the disasters was that the temperature suddenly decreased below 0℃, the temperature changes ranges were -25.6℃--0.8℃.