Climate Characteristics Analysis of Relative Humidity in Urumqi in Recent 40 Years

Using the day-to-day average relative humidity in Urumqi from 1961 to 2000,the climate characteristics,variation and change trend of relative humidity in Urumqi in 40 years were analyzed.The main results showed that the year average relative humidity in Urumqi was 57.5%.The average relative humidity in winter was 77.5%,the highest season in a year,while the average relative humidity in summer was 41.2%,the smallest season.The relative humidity in spring,summer,autumn,winter,and a year all increased in recent 40 years.The prominent periods of annual mean relative humidity are 2 years,3-4 years and quasi-7 years.The oscillation of quasi-7 years period was the strongest.