Emily is conducting an experiment to investigate factors affecting transpiration rates in plants. She sets up three identical potted plants in different environments. Plant A is placed in a sunny location with plenty of air circulation, Plant B is placed in a shady location with minimal air movement, and Plant C is placed in a closed glass container. After a day, Emily observes that Plant A has lost the most water through transpiration, followed by Plant B, and Plant C has lost the least. What is the most likely factor influencing transpiration rates in this scenario?