How does the rate of evaporation of the crystal growing medium affect the final size of the crystal?

Answer 1

It's a big circle: Rising air currents take the water, as vapor, up into the atmosphere, along with water from "evapotranspiration," which is water transpired or "breathed out" from plants and evaporated from the soil. The cooler temperatures in the atmosphere cause it to condense into clouds, which float around until the fall from the sky as precipitation. Some precipitation falls as snow and can accumulate as ice caps and glaciers, where it can stay, as frozen water, for thousands of years. In warmer climates, snow melts during the warmer spring and summer months, and that water flows into streams and rivers, which eventually return it to the ocean, or into the groundwater, which eventually reach underground aquifers. Over time, the water continues flowing, some to reenter the ocean, where the water cycle renews itself. There are four basic steps that tie this all together

Answer 2

Faster evaporation rates tend to result in smaller crystals because the dissolved particles don't have as much time to arrange themselves into larger crystal structures. Slower evaporation rates allow for more growth time, leading to larger crystals with more developed structures.