The midnight sun is a natural phenomenon in which the sun is above the horizon for more than 24 hours.
Then how is called the phenomenon in which the sun is below the horizon?
Answer:
Have you ever experience the midnight sun? I never have...
Oh well, it's just a simple question, isn't it?
Read the question carefully, and precisely understand what is asked.
I didn't say "below the horizon for more than 24 hours"...