彩虹！
Cǎi hóng!
Colorful rainbow!
Single word exclamation
快看，天上有彩虹！好漂亮！
Kuài kàn, tiān shàng yǒu cǎi hóng! Hǎo piào liang!
Quick look, sky has rainbow! So beautiful!
好漂亮 = so beautiful, natural exclamation
天边挂着一道美丽的彩虹，赶快拍下来！
Tiān biān guà zhe yī dào měi lì de cǎi hóng, gǎn kuài pāi xià lai!
A beautiful rainbow hangs at the edge of the sky, quickly capture it!
天边 = horizon/edge of sky; 一道 = classifier for rainbow; 拍下来 = capture a photo
More Chinese (Mandarin) Weather Phrases