light, bright, clear morning 2 realizations
ACCEPTED Realization 1
Type Cognates
Language 1 Classical Arabic
Language 2 Jewish Aramaic
Lexeme 1 أَصْفَر ʔaṣfar-
Lexeme 2 ṣəpar, ṣiprā
Meaning 1 yellow; pale
Direction
Meaning 2 morning
Reference BK: I 1347 Jastrow: 1298
Comment

It seems plausible that the shift has been intermediately realised via the meaning "clear". 

ACCEPTED Realization 2
Type Derivation
Language Classical Arabic
Lexeme 1 أَصْبَحَ ʔiṣbaḥa
Lexeme 2 صُبْح ṣubḥ-, ṣibḥ-
Meaning 1 to become clear

أَصْبَحَ الحقّ


the truth has been revealed

Direction
Meaning 2 morning
Reference BK: I 1304
Comment

The root ṣbḥ relates to the circle of meanings "morning", “to go up in the morning” etc.