RLO: Concentration Gradients



The term gradient can be used in many contexts to indicate a relation between greater and lesser quantities. If you pour yourself a hot cup of tea, for example, the tea will be hotter than the surrounding air, a relationship which can be expressed as a temperature gradient between the heat of the tea and the cold of the air. If you dropped an ice cube into the tea the temperature would go from freezing to near boiling in a short distance, resulting in a sharp temperature gradient. As a further example, an inflated bicycle tyre represents a sharp pressure gradient between the pressure in the tyre and that of the atmosphere.