43rd day of 2016. 5th day of Chinese New Year.
Continuing on world building. Previously in World Building - Climatology 1 a basic study of our own Earth is done on seasons. As my objective is to have the whole globe experience the same season at the same time, I play around and came out with this.
Off centre elliptical shape orbit would be the most obvious reason how the whole globe could have different seasons and at the same time. I got this orbit shape base on comet's elliptical orbit. So in a way, it is not all that alien even though my world is a planet, not a comet.
When you solved the seasons, you would have an idea how to make up the calendar. Since I figure my world's inhabitant started out with observing the season in primitive era, I used the most raw and primitive, most importantly, the most straightforward way of naming for the months. Early, Mid and Late. It is very much related to how they lead their life.
Now come to some details. When I said 'at the same time', I don't literally meant accuracy down to minutes or even hours. The season would of course be affected by the landmass of the planet. I have a simple study of how the differential would most probably occur.
The Higher the altitude, the earliest it could receive sun rays to change season. As the temperature travel down slowly, the Lower altitude would change season. Generally, all spot on planet would receive 3 months of each seasons, but just not in the same weeks.