九华山山地雾形成的气象条件及地形影响

Meteorological Conditions and Terrain Effect the Formation of Mountain Fog in Mount Jiuhua

雾是九华山最常见的天气现象之一,其年平均雾日为145 d,年最多雾日达到168 d。因此,利用九华山不同海拔的测站及区域自动气象站的资料,分析山地雾形成的气象条件和地形的影响作用。结果表明:山区雾的年际变化较大,并呈逐年递减趋势,雾生成时间峰值在05时前后,但出雾频率最高的是在08时。山区夜间降温≥6℃的雾日占总雾日数的74.4%,气温日较差≥7.0℃的雾日占总雾日数的80.9%,雾日多出现在日平均风速<3m/s的条件下,83.9%的雾日有近地面逆温层存在,并且雾日数与逆温强度是呈正相关的。喇叭口地形的辐合作用有利于水汽在喇叭口底部区域达到饱和,形成雾,在微风的条件下对辐射雾的形成非常有利,如果近地面层有风场的辐合作用,更是有利于雾的形成与维持,森林小气候的作用也有利于雾的形成。

Fog of Mount Jiuhua is most common weather phenomenon, its average annual fog days for 145 days, the maximum annual fog days to 168 days. This paper uses the Mount Jiuhua different elevation on the station and the regional automatic weather station data, analysis of mountain fog formation of meteorological conditions and terrain effect. The results show that ： the mountain fog large inter-annual changes, and has been decreasing trend, fog genera- tion time peak in 05 oclock when around, but the fog is the highest frequency in the 08 oiclock. Mountain night cool- ing is greater than or equal to 6 °C of the total number of days of fog in 74.4%, the diurnal temperature range is greater than or equal to 7 °C of the total number of days of fog foggy day 80.9% days of fog, appear in the daily mean wind speed is less than 3 m/s ,83.9% days of fog is near the ground inversion layer exists, and the number of days of fog and inversion intensity is positively related to the.Trumpet-shaped topography convergence of water tion, formation of fog in the breeze, under the condition wind field convergence, is conducive to th~ formation contribute to the formation of fog. vapor in the flared bottom area is conducive to reach satura- of radiation fog formation is very advantageous, if the surface and maintenance of the fog, forest microclimate effects also