I've actually worked on two Eco-themed projects this week and both had the explicit instructions: no green leaves and no trees. Which is kind of tough, actually.
For this pattern I decided to stick to the no leaves, no trees rule. I thought back to my middle school biology class where we made small, plastic eco systems.
I remember being pretty astounded that weeks or months later, condensation was still forming along the sides and dripping back down to water the plants contained within.
Clean water is a pretty big deal and it's only becoming more rare and precious. So this pattern is dedicated to the natural cycle of evaporation, condensation and clouds feeding other clouds.