The Comparison of Variation Features of Diurnal Meteorological Elements at DaLi,LiTang and Linzhi Stations

Diurnal variation features of air temperature,relative humidity,pressure,instantaneous wind speed,surface temperature were analyzed by using automatic weather stations data of Dali,Litang and Linzhi.The daily results showed that the minimum air temperature and maximum relative humidity of Dali,Litang and Nyingchi occurred respectively at 7:00,around 7:00 and 8:00,the maximum air temperature and minimum relative humidity occurred all at 16:00.Pressure showed nearly the shape of peaks and two vales,where two peaks presented at around 10:00 and 0:00～1:00 and two vales presented at around 17:00 and 5:00 respectively.Lower wind speed increased after 7:00 untill reaching its maximum value before evening.The minimum and maximum value of surface temperature occurred at around 7:00 and 14:00.From seasonally results could find that the month were similar,when air and surface temperature occurred the biggest alteration range,maximum value and minimum value.Surface temperature had the most obvious increase and decrease magnitude in spring and autumn.Pressure variation magnitude with season was lower than air temperature,relative humidity.Wind speed was larger in early spring,whereas was smaller in autumn,it had influence on relative humidity in certain.The month were similar at Dali and Nyingchi when relative humidity was the lowest and wind speed was maximum.Above meteorological elements showed basically the largest value in Dali,the second in Linzhi,minimum in Litang,which was correlated with latitude,altitude and underlying surface.