Why does cold make the bigger crystals?

Cold temperatures slow down the movement of molecules, allowing them to arrange themselves into a more orderly and stable structure, which leads to the formation of larger crystals. In a cooler environment, the reduced thermal energy decreases the rate of nucleation—where new crystals begin to form—allowing existing crystals to grow larger instead of numerous smaller ones forming. Additionally, lower temperatures often enhance the solubility of certain substances, promoting the growth of larger crystals over time.