- 날이 밝다.
The day is bright.
- 날이 밝는다.
The day dawns [breaks].
When I tried doing a Google search on "날이 밝다," I found that many Koreans are using it to mean "dawn," which is a misuse of the word since "dawn" should be "날이 밝는다." In other words, some Koreans do not seem to understand the difference between the verb 밝다 and the adjective 밝다.
As one might expect, the adjective 밝다 is used in more situations than the verb 밝다. For example, when I did a Google search on "밝는다," which would be referring to the verb 밝다, I found only a limited number of subjects used with it. They were essentially 날이 밝는다 (the day dawns), 아침이 밝는다 (the morning breaks), and 해가 밝는다 (a new year dawns).
By the way, 맑다 is an adjective with meanings that include, "clear," "clean," "fair," "fresh," and "pure." It has no verb function, which means that 맑다 should not be used in the form of "맑는다." Nevertheless, if you do a Google search on "맑는다," you will find that many Koreans are mistakenly using 맑다 as a verb.