The origin of "break of day"

I was quite surprised to know that "break of day" actually means "dawn", that is, the beginning of the day.

But, the phrase "break of day" sounds much more like the end of the day, not the beginning of it. So, I'm quite interested in the origin of it.

Daybreak (n.) is quite an old expression:

• 1520s, from day + break (n.).

Break:

• Meaning "to disclose" is from early 13c.

(Etymonline)

Ngram shows that both expressions, daybreak and break of day, have been used from the 16th century.

At the crack of dawn is a similar expression:

• Fig. at the earliest light of the day. Jane was always awake at the crack of dawn. The birds start singing at the break of dawn. (McGraw-Hill Dictionary)