In meteorology , they are called cirrocumulus clouds 气象学上称这种云为卷积云。
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Under the influence of atmospheric waves which are often present at high altitudes , the clouds line themselves up and move with the upper level winds , forming the cirrocumulus clouds having a fish - scale appearance 云朵受高空波状气流所影响,组成行列,并随著高空的风向飘移,形成鱼鳞一样的卷积云。
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Cirrocumulus clouds are high clouds , generally with a cloud base at above 6000 metres where the temperatures are several tens of degrees celsius below zero . they are composed of tiny ice crystals and are thin and translucent 卷积云属于高层云种,云底高度一般在6000米以上,温度是摄氏零下数十度,云朵全部由细小的冰晶构成,薄而透光性高,看起来有蚕丝般的光泽。
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The occurrence of cirrocumulus clouds indicates the distant presence of a convergent zone such as a pressure tough or a cyclone in lower levels ; or a frontal zone where cold air meets moist warm air . vigorous convection and lifting motion bring water vapour up in the sky where the water vapour sublimes into ice crystals , forming the high clouds 卷积云的出现显示远处地方低层有一强辐合带如低压槽或气旋或锋面即暖湿空气碰到冷气团,向上爬升的交界面形成,强烈的对流和抬升运动将水汽带到高空,在那里水汽直接升华变为冰晶而形成高层云。
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Mackerel sky , not twenty - four hours dry describes the deterioration of weather after the appearance of cirrocumulus clouds . although it may be bright at the beginning , the weather will deteriorate in half a day s time as the cyclone or front approaches . as they pick up more moisture , the cirrocumulus clouds thicken and extend downward to become low - level clouds which bear rain 鱼鳞天,不雨也风颠是形容卷积云出现后天气转坏的状况,虽然初时天气明朗,但约半天光景后,天气会随气旋或锋面的移近而转坏,风速增强,卷积云也会随著水气增加而逐渐增厚,云层向下伸延转为低层云,产生降雨。