noun
clear weather; blue sky and bright sun
Literally describes a cloudless sky with the sun shining brightly. Used in literary or formal descriptions of fine weather.
青天白日の下、運動会が行われた。
The sports day was held under a clear blue sky.
noun
cleared of charges; proven innocent; clear conscience
Figurative use: being publicly cleared of suspicion or accusation, or having a completely clear conscience. Often used in the phrase 青天白日の身となる.
長い裁判の末、彼は青天白日の身となった。
After a long trial, he was cleared of all charges.
証拠が見つかり、彼の疑いは晴れて青天白日となった。
Evidence was found, and his suspicion was cleared, proving his innocence.