1.
It can be helpful to think of signs that are said to be masculine as diurnal and signs that are said to be feminine as nocturnal. Diurnal is form, definition, materiality. Illumination. In contrast nocturnal is the unseen, what is left out of definition, intuitive. The dark. What is finite and tangible and how that works in tangent with what is void like and infinite.
Air is about connection but it is also about language. It is giving structure to our thoughts to help us perceive the material world around us. It is interested in delineating the world around us and giving it structure. That is all about some level of hard definition and judgement. We actually literally perceive the world differently based on the language we use. This is how air is diurnal imo.
Earth is intuitive and subtle I feel like this often comes out as a practicality. Even Virgo the sign about reaping the harvest, counting, and delineating I notice is often succinct. There is a guidance maybe from what is grown and reaped and they are only speaking to that. There are ways of knowing outside the easily quantifiable or outside of language. Earth is more attuned to that undercurrent and that is perhaps part of how it is nocturnal.
2.
Throughout ancient history, earth and water have been associated with the female (womb). Earth receives (seeds are planted) and gestates (gives birth) to new life.
From Aristotle, to Hermeticism, to ancient Sumerian / Akkadian mythology:
Sumerian: Ki = Earth (Feminine), An = Sky (Masculine)
Ninhursag / Nintu / Aruru: The Earth-Mother as Womb
Air/Wind as Male: Enlil[…] you are thinking of masculine / feminine as personality traits and not the cycle of creation. Our ancient ancestors thousands of years ago were thinking about the life creation cycle.