The Analysis of the Meteorological Cause of Formation of Forest Fire in Da Hinggan Ling Region

In this paper, the meteorological factors of the catastrophic forest fire in Da Hinggan Ling region of northeastern China in May, 1987 have been analysed. It is found that the drought and less rainfall in the previous period, and much higher temperature in the first ten-day of May are the climatic conditions of the forest fire. Da Hinggan Ling region is located in northeastern China, which is part of the frigid-temperate zone and the annual mean temperature is -3 to -6oC. Therefore, the organic matters are decomposed rather slowly and make more and more combustibles accumulated in the forest, It provides the material condition of the fire. A very strong dry cold front with the average wind speed 8—12 m/s, and the extreme speed 17.0 m/s, just passed away when a large number of fire points were in existence, which spreaded the fire over wide areas rapidly. This is the key factor of the fire. In addition, the topographic factor which related to the temperature and the snow cover also affected the extension of the fire