Several parts combine into one character.

Phonetic-semantic compound: 日 (sun) + 青 (blue / green / fresh). The encoding is gorgeous — sun against blue sky = clear weather. The picture matches the meaning so cleanly that no further explanation is needed. Identical across 繁體 / 新字体 / 简体.

青 here doubles as both phonetic (lending its sound qing/sei) and semantic (lending the blue-sky image). This kind of layered phonetic-semantic loan is common in CJK characters where 青 anchors a phonetic family: 晴 (clear), 清 (clean / pure water), 静 (quiet / still), 情 (emotion / circumstance), 請 / 请 (request) — all sharing the qing/sei pronunciation but built on different left-side semantics. Recognizing this 青-family is one of the key shortcuts for guessing pronunciations of unfamiliar characters.

Mandarin: qíng, rising 2nd tone. 晴天 (qíngtiān, clear day), 晴朗 (qínglǎng, sunny / bright), 晴空万里 (qíngkōng wànlǐ, "clear sky for ten thousand miles" — perfect blue sky idiom). Weather forecast vocabulary essential for everyday Chinese.

Japanese: on-reading セイ (sei) in compounds — 快晴 (kaisei, perfect clear weather), 晴天 (seiten, clear sky). Kun-readings dominate everyday usage: は.れる (ha.reru, to clear up — verb), はれ (hare, sunny — noun used in weather reports). Every Japanese weather forecast uses 晴れ to mark sunny days, paired with 雨 (ame, rain) and 曇り (kumori, cloudy). 晴れ is also figurative — 晴れの日 (hare no hi) means "a day of celebration / a special day" (as in "wedding day"), because clear weather is auspicious.

The Japanese phrase 晴れ着 (haregi, "clear-weather clothes") refers to formal kimono worn for celebrations — extending the meteorological metaphor to social occasion.

Memory aid: sun + blue = clear weather. Sun against blue sky.