Final answer:
The term 6.4°C/1000 m (3.5°F/1000 ft.) is associated with the temperature lapse rate, indicating how much temperature decreases as altitude increases.
Step-by-step explanation:
The term 6.4°C/1000 m (3.5°F/1000 ft.) refers to the temperature lapse rate, which is a measure of how much the air temperature decreases with an increase in altitude.
The lapse rate is critical in understanding weather patterns and the behavior of the atmosphere. A stable lapse rate is approximately 6.5 K per km (or equivalent in Fahrenheit per feet), but this value can vary depending on atmospheric conditions.