Conflicting Viewpoints: Student 1 argued that the unexpected data from wind mixing in a lake disproved the model. Student 2 argued that a limit, condition, missing variable, or revision could reconcile the evidence. The model says that a warm surface layer forms whenever lake surface water is heated during the day. Figure 70 shows: condition: calm morning, calm afternoon, windy afternoon, windy evening; predicted surface-bottom temperature difference (deg C): 1, 7, 7, 4; measured difference (deg C): 1.2, 6.8, 1.5, 0.8. The conflict is that the windy afternoon had little temperature difference despite daytime heating. Which explanation best supports Student 2's interpretation?