Answer:
I can wave my hands at you but I never say goodbye. You are always cool when with me even more so when I am high!
My days are numbered.
I come without being fetched at night, hide away as soon as daylight strikes. Although I may look small, I am much mightier than what you can imagine. What am I?
If a man carried my burden, he would break his back. I am not big but leave silver in my tracks. What am I?
I fly when I'm on and float coming off.
When someone uses this acronym, you know you've got to pick up the pace