Mythical creatures of the Cervidae or Caribou family that possess the innate ability to attain flight. They migrate above the Troposphere and rain is caused by their tears. They mate within the comforts of Alto-cumulus clouds.
Aeso: We have had a long cold winter, brother. The rains become ice and would not stop for weeks on end.
Filipus: Yes, brother, it would seem the Raindeer have been quite miserable.