You can remember the meaning of 明明 with this easy mnemonic:
The horse trainer whistled a <strong>bright</strong> (明) <strong>clear</strong> (明) note that pierced through the field. However, there was no horse in sight to the viewers' confusion. The horse trainer was <strong>obviously</strong> an experienced trainer.
Using mnemonics to remember the meaning of Chinese characters like can have an enormous impact on how long to learn Mandarin it takes.