多云天 meaning in English

broken sky
clouds
cloudy sky
partly overcast sky

They cannot concentrate the diffused sunlight of cloudy days .
它们不能收集多云天的散射阳光。
The daily variation of surface o3 is different under different weather condition , the variation of surface o3 in spring , autumn and summer is almost same when it is clear . in spring and autumn , under the condition of clear sky , its value is higher than that in cloudy or rainy / snowy day , while its variation is not obvious in winter and summer ; in rainy and snowy season , the variation of surface o3 in spring , autumn and winter is insignificant , bnt in summer , it is significantly different from other seasons , daily difference is the highest among all seasons , it has some important relationship with rain / snow , moreover , the function of rain and snow to the varation of surface o3 is different
( 2 )不同天气条件下，春、夏、秋、冬四个季节地面o _ 3浓度变化不尽相同，晴天和多云天，春、夏、秋季的地面o _ 3变化趋势基本一致，其中，春秋季，晴天o _ 3值高于多云天和降雨天，而冬季和夏季则不明显；各季节降雨、雪天o _ 3浓度的变化情况来看，地面o _ 3在春、秋、冬三个季节变化不大，而夏季与其它季节明显不同，变化幅度很大，日较差在四个季节中为最大，这与降雨、降雪关系很大，并且可能存在雨、雪的差异。