Boeing 737-800 (N508AS)

Outstanding shot!

I see downward pointing wing tips in addition to the normal upward wing tips. What is the rationale behind?

Looks like an antenna of some sort on the right wing tip

Scimitar winglets. Vortex reduction/lift preservation.

Um ar muito agressivo, mas bonito.

Al it's a Scimitar Winglet. The bottom winglet is angled making it kind f appear to be going straight back. So pretty much top and bottom winglets with the bottom angled out. You can slightly make out the left wings lower winglet which makes it clearer.