(This was a question asked by a child).
Different reasons exist behind covering the head. Sanyasis cover the head for important reason. In temples people cover their head as a mark of respect. Swamiji ties a head band so as to preserve the energy from my Lambika chakra from flowing out. You may then wonder why Swamiji does not wear the band at all times? I do so purposely. Let the Lambika chakra be visible I think at times.
Another reason is to prevent the wind from messing up my hair.
(Q&A Session 13 Dec 2015)