The world of Astrasida is vast - about 70 times larger than Earth. As such, it is not divided into hemispheres, but quadrispheres - and as an indication of what this means, both the Astral Empire and the vast territories of the Concord exist solely within the Southeastern Quadrisphere. The climate of the Southeastern Quadrisphere varies greatly, but it follows the generally-observed effects of polar-to-equatorial flora and fauna variation - nearer to the spatial pole, vast areas of ice and snow can be found, below it more temperate climes and accompanying coniferous trees and wetland plants, and as the territories approach the equator, expansive grasslands, and finally those mountainous jungles common to equatorial regions on this planet.
There is little about Astrasida that adheres to science, save the aforementioned elements, which are there to provide a sense of familiarity and grounded-ness, and not to create some sort of mish-mash 'hard fantasy' planet. Gravity works on Astrasida as it does on Earth, for this is a fantasy tale, and with fantasy comes the liberty to adjust elements of reality to one's liking - it would hardly be fantasy otherwise.