【“七彩祥云”现身颐和园上空】今年清明假期最后一天，北京颐和园上空出现“七彩祥云”。这种大气光学现象名叫日华，太阳光穿过薄薄云层中的小冰晶发生折射和衍射，呈现出肉眼可见的七色光芒。（图片来源：视觉中国）A breathtaking burst of iridescent clouds dazzled above the Summer Palace on Monday, painting the sky with shimmering rainbow colors. The rare phenomenon, often considered an auspicious sign in China, appeared like a celestial painting, glowing and shifting above the imperial garden.